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Acta Psychologica xxx (2010) xxx–xxx

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Acta Psychologica j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / a c t p s y

Emotional valence of spoken words influences the spatial orienting of attention☆ Julie Bertels a,b,⁎, Régine Kolinsky a,b, José Morais c a b c

Université Libre de Bruxelles (U.L.B.), Belgium Fonds de la Recherche Scientifique – FNRS (F.R.S.–FNRS), Belgium Université Libre de Bruxelles (U.L.B.), Belgium

a r t i c l e

i n f o

Article history: Received 18 December 2008 Received in revised form 23 February 2010 Accepted 24 February 2010 Available online xxxx PsycINFO classification: 2346 Attention 2360 Motivation & Emotion Keywords: Auditory attention Cognitive bias Emotional content Spoken words

a b s t r a c t The influence of the affective content of speech on the spatial orienting of auditory attention was examined by adapting the dot probe task. Two words, one of which was emotional in one quarter of the trials, were played simultaneously from a left- and a right-located loudspeaker, respectively, and followed (or not) by a lateralized beep to be detected (Experiments 1 and 2) or localized (Experiment 3). Taboo words induced attentional biases towards their spatial location in all experiments, as did negative words in Experiment 3, but not positive words. Thus, in audition, the identification of an emotional word automatically activates the information about its spatial origin. Moreover, for both word types, attentional biases were only observed when the emotional word was presented on the participant's right side, suggesting that the dominant left hemisphere processing of words constrains the occurrence of spatial congruency effects. © 2010 Elsevier B.V. All rights reserved.

1. Introduction The present work examines whether the affective content of speech influences the spatial orienting of auditory attention. If so, an emotional word might facilitate or interfere with the processing of an unrelated, simple auditory signal subsequently presented, depending on whether this signal shares the spatial origin of the speech stimulus or not. It has been proposed that the auditory system, like the visual one, is composed of two parallel streams of processing: the “what” and the “where” subsystems (Kubovy & Van Valkenburg, 2001). The dissociation of these two subsystems is supported, for example, by the observation of an illusion in which a sequence of pitches is perceived correctly but in the wrong ear location (Deutsch & Roll, 1976), and by the fact that adaptation may have a detrimental effect on localization while leaving pitch perception unaltered (Hafter, 1997). The two auditory subsystems seem to rely on distinct cerebral structures: the “what” subsystem relying on the superior temporal cortex and the

☆ The first author was a Research Fellow of the Fonds de la Recherche Scientifique (F.R.S.–FNRS) and is presently a Scientific Research Worker of the F.R.S.–FNRS. The second author is a Senior Research Associate of the F.R.S.–FNRS. All authors were affiliated to the Research Unit in Cognitive Neurosciences, Université Libre de Bruxelles. ⁎ Corresponding author. UNESCOG, Université Libre de Bruxelles, Avenue F.D. Roosevelt, 50, C.P.191, 1050 Brussels, Belgium. E-mail address: [email protected] (J. Bertels).

“where” subsystem on the medial, posterior auditory cortex (Clarke, Bellmann, Meuli, Assal, & Steck, 2000; Rauschecker, 1997, 1998a,b). In audition, as perceptual form and organization are not processed in relation to space, possible links between the “what” and the “where” auditory subsystems have been underestimated (see Kubovy, 1988). Still, it can be argued that such functional links afford us an ecological advantage. In peripheral space, beyond a 20° visual angle, auditory targets elicit shorter orientation latencies than visual targets (Goldring, Dorris, Corneil, Ballantyne, & Munoz, 1996) and, at night, the identification of sounds signalling either danger or urgent requests for help may require auditory localization. Consequently, identification of an auditory object relevant for survival (or at least for ecological adaptation) might automatically activate information about the spatial location of its source in order to orient spatial attention to the same location. This would put the listener in a better attentional state to process subsequent auditory (or visual) information coming from the same source. For example, identifying the kind of animal that produced a particular cry should, in principle, influence the level of attention devoted to its position in space and therefore the accuracy and/or rapidity of detection or localization of subsequent signals coming from the same direction. Obviously, not all auditory objects convey shallow, non-symbolic, information. Spoken words are auditory objects that transmit highly abstract information, including semantics. As regards spoken words, some refer to emotional states or are emotionally loaded. Although emotional words are not more directly relevant for survival than

0001-6918/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.actpsy.2010.02.008

Please cite this article as: Bertels, J., et al., Emotional valence of spoken words influences the spatial orienting of attention, Acta Psychologica (2010), doi:10.1016/j.actpsy.2010.02.008

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J. Bertels et al. / Acta Psychologica xxx (2010) xxx–xxx

neutral words (especially when uttered in a neutral intonation), their identification might evoke emotional feelings, boost the attentional system and trigger the “where” auditory subsystem, influencing the orientation of spatial attention. Many authors examined the spatial orienting of auditory attention, namely the characteristics of the auditory “where” subsystem, without considering the involvement of the “what” subsystem (e.g., Buchtel & Butter, 1988; Rhodes, 1987; Spence & Driver, 1994). Most of these studies used an auditory variant of the cuing paradigm (Posner, 1980), in which a peripherally-presented auditory cue is followed by an auditory target, presented either at the same location as the cue or at the opposite location (in valid and invalid trials, respectively). Exogenous attentional orienting to the spatial location of the cue is reflected by the validity effect, namely the reaction time (henceforth, RT) difference between invalid and valid trials. In the present study, we used a variant of the auditory cuing paradigm to attempt to assess the impact of the emotional content of word cues, relying on the “what” subsystem, on the spatial orienting of auditory attention. This variant actually consists of an adaptation to the auditory modality of the dot probe task (also called attentional deployment task, MacLeod, Mathews, & Tata, 1986) used in the visual modality to examine the role of the emotional content of written words on the spatial orienting of visual attention. In the dot probe task, two written words, either one emotionally loaded and the other not, or both neutral, are presented one above the other. In half of the trials, the words are followed by an unrelated visual target (a dot) in the location that was previously occupied by one of the words. On congruent trials (i.e. valid trials, in the terminology of the cuing paradigm), the dot is presented at the same location as the one previously occupied by the emotional word, while on incongruent (i.e. invalid) trials the dot is presented at the opposite location. In our auditory adaptation of the dot probe task (named the beep probe task), during each trial two different spoken words were presented through loudspeakers in a diotic way, i.e. simultaneously, one on the left and the other on the right side of the listener. The use of loudspeakers instead of headphones was motivated by the ecological advantage of making sounds come from the external world. In the relevant trials, one of the words was emotional and the other was neutral. In half of the trials, a lateralized single beep target followed the presentation of the pair of words. The use of an auditory target instead of a visual one, as in the dot probe task, allowed us to keep the unimodal aspect of the original paradigm. The congruence or incongruence between the presentation side of the emotional word and the presentation side of the beep was critical. Consistent with the underlying idea of the cuing paradigm that the faster the participant reacts to a given location, the most attention was attracted in this location (Posner, Snyder, & Davidson, 1980), the prediction derived from the auditory “what– where” connection hypothesis was that the spatial congruence between the emotional word and the beep would lead to shorter RTs than their spatial incongruence, hence creating what is called an attentional bias, following MacLeod and Mathews' (1988) terminology. It must be noted that the auditory “what–where” connection hypothesized here needs not be emotion-dependent. However, as in the present situation only one of the diotic stimuli was emotional, any spatial congruency effect implies that the “what–where” connection is driven (or at least is reinforced) by the emotional member of the diotic pair, not by the neutral one. Given that both the words and beeps were presented in a lateralized way, perceptual laterality effects related to hemispheric specialization were likely to be observed. Indeed, as shown by Demakis and Harrison (1994), both neutral and affective words are mainly or more efficiently processed by the left hemisphere, at least

when the emotional content of the word is irrelevant to the task. Furthermore, as Kinsbourne (1970) argued, the presentation of verbal material could activate the left hemisphere preponderantly, thus leading to involuntary orientational biases to the right side of space. To this hemispheric imbalance hypothesis one may add the assumption that an emotional word catches more attentional resources than its paired neutral word, and therefore activates the hemispheric contralateral to its side of presentation to a greater extent than the ipsilateral one. Thus, taking these two assumptions together, one may predict the attentional bias to be stronger when the emotional word is presented on the right side. Indeed, in this case, the processing of a right-sided beep would be favoured by both attentional mechanisms, the “hemispheric” and the “emotional” one, whereas processing of a left-side beep would be disadvantaged by both. In contrast, if the emotional word is presented on the left side, processing a beep presented on either the left or the right side would benefit from one of the two mechanisms, either the “emotional” or the “hemispheric” one, respectively, but would be disadvantaged by the other mechanism. The influence of the emotional content of a word on attentional orienting could depend on its specific emotional valence. Because the rapid processing of positive information does not seem to be as crucial for the organism's well-being as is the processing of negative information (Baumeister, Bratslavsky, Finkenauer, & Vohs, 2001; Grühn, Smith & Baltes, 2005; Rozin & Royzman, 2001; Taylor, 1991), we hypothesized the “where” auditory subsystem to be more likely triggered by negative and taboo words (namely vulgar, shocking or obscene words, as well as insults) than by positive ones. Hence, we expected taboo and negative spoken words to facilitate the processing of the beep presented at the same spatial location (compared to its presentation at the opposite side) to a greater extent than positive words. This effect would be larger for right-presented emotional words, as argued above. Experiment 1 consisted of an auditory adaptation of the original version of the dot probe task. As in this task, the participants were required to detect the presence of the non-linguistic target in each trial, here the beep. Also, given that in the visual paradigm participants were asked to read the word presented in the upper position in order to be sure they paid attention to the linguistic stimuli, we asked them to repeat the word presented through a prespecified loudspeaker after responding to the beep in Experiment 1. Given that only effects of taboo words emerged, we eliminated this repetition task in a second experiment, speculating that it might have monopolized some attentional resources, making it difficult for negative words to facilitate selectively the detection of a same-side beep. In addition, the attentional biases observed in Experiment 1 for taboo words could have been due to the fact that participants had to pronounce these shocking words in front of the experimenter. Elimination of the repetition task thus allowed us to both reduce the cognitive load and remove this potential bias. Finally, in a third experiment, we used a localization rather than a detection task in order to introduce a spatial component in the task, given that spatial validity effects have been observed more frequently in the auditory cuing paradigm when spatial representations are somehow relevant for the participant's goal (Rhodes, 1987; Schmitt, Postma, & De Haan, 2000; Spence & Driver, 1994). 2. Experiment 1: Beep probe detection and word repetition This experiment was intended to be a close auditory analogue of the classic version of the dot probe task (MacLeod et al., 1986, see also e.g., Fox, 1993 and Salemink, van den Hout, & Kindt, 2007), using lateral stimulations. We did not use up–down stimulations because these proved to be exceedingly hard to discriminate. Neutral, negative, positive and taboo words were presented. Participants were asked to detect the target — here, a beep — and to then repeat a


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word of the pair presented on a pre-specified side, in the same way that they had to read aloud the upper word of the pair in the original version of the dot probe task in order to make sure they paid attention to the linguistic stimuli. Following the auditory cuing literature, the use of a detection task would prevent the occurrence of any validity effect (Rhodes, 1987; Schmitt et al., 2000), at least when loudspeakers and uninformative cues are used (Spence & Driver, 1994). Indeed, the lack of any spatial representation linked to the task would probably preclude spatial orienting towards the location of the auditory cue. Nevertheless, Buchtel, Butter, and Ayvasik (1996) argued that validity effects are observed with a detection task when there is an orienting reaction towards the source of the sound, namely in conditions favouring the intention to orient the head to a sound source. Following this idea, given the instruction to repeat a word presented on a pre-specified loudspeaker on each trial (i.e. to orient attention voluntarily towards one side of the auditory space) and in spite of the fact that a detection task and uninformative cues were used in Experiment 1, we expected to observe congruency effects between the position of the emotional word in the pair and the position of the following beep. As any activation of the “what–where” connections is presumably due to the need to register relatively rapid changes in the environment, we assumed that it would be transient. To test this idea we used two word-beep intervals here, one short and one long, and expected the predicted attentional bias (i.e. facilitated processing of the beep presented at the same spatial location as the emotional word of the pair, compared to the beep presented at the opposite side) to occur with the short interval, not — or at least less so — with the long one. Moreover, if an attentional bias were to occur in the long interval condition, we predicted it to be negative. Namely, participants would detect the beep faster if presented at the opposite location (i.e. at the location of the neutral word) than if it was presented at the same location as the emotional word. As a matter of fact, given the lengthening of the SOA (Stimulus Onset Asynchrony, i.e. the time between the onset of the word and the onset of the beep) in this condition, one could expect an inhibition of return phenomenon (IOR, cf. Posner & Cohen, 1984) to occur: with long SOAs, attention oriented to the location of the cue would come back to a central location for the application of inhibitory processes to the location previously explored, making it easier to process any information coming at the opposite rather than at the same location as the cue. 2.1. Method 2.1.1. Participants Participants were 35 first-year students of the Université Libre de Bruxelles (31 women; 3 left-handed), ranging from 17 to 40 years (mean: 20.3). They were given course credits for their participation. The results of three women, all right-handed, were discarded from the analyses: two because their average RTs (all experimental conditions mingled) were superior to two standard deviations above the overall average performance, and one because of her inability to repeat correctly the presented words. All participants had spoken French for at least the last 10 years. Previous studies investigating attentional biases in the visual modality pointed to the robustness of this phenomenon only in selected groups of participants such as anxious subjects (e.g., BarHaim, Lamy, Pergamin, Bakermans–Kranenburg, & van Ijzendoorn, 2007), repressors (Mogg et al., 2000) and depressed people (e.g., Mogg, Bradley & Williams, 1995). Therefore, we used personality questionnaires (filled in after the beep probe task) evaluating anxiety and depression levels (the Spielberger Trait-State Anxiety Inventory, STAI-Y; Spielberger, 1983, and the Beck Depression Inventory, BDI–II; Beck, Steer, & Brown, 1996, respectively), as well

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as willingness to be socially desirable (the Marlowe–Crowne Scale of Social Desirability, SDS; Crowne & Marlowe, 1960) in order to examine whether these measures would correlate with the emotional effects. Table 1 displays the average scores obtained in these questionnaires. Participants were randomly assigned to one of four groups (8 participants in each group) created on the basis of the pair-beep interval length (short/long) and the side of the auditory space (the loudspeaker) to which they had to pay attention in order to repeat the word presented on that side (left/right), hereafter called repetition side.

2.1.2. Material and apparatus Words were orally presented. They were spoken by a Frenchspeaking female theatre student in a neutral tone of voice and were digitally recorded on a Sony MiniDisc. Stimuli were then transferred on a Macintosh Powerbook G3 via the Digidesign DIGI 002 Rack interface and were cleaned and normalized with the Protools Digidesign 6.2.2. software. Mean word duration was 719 ms (standard deviation: 135 ms). The words used in this experiment (as in the following ones) were chosen as described below. There were 480 pairs of mono- or bi-syllabic words: 120 emotional pairs, in which one of the words was emotionally neutral and the other was emotionally charged (see Appendix A), and 360 neutral pairs, consisting of two emotionally neutral words. Emotional pairs included 40 positive (e.g., amour/ agence — love/agency), 40 negative (e.g., bombe/bulle — bomb/ bubble) and 40 taboo pairs (e.g., salope/serrure — bitch/lock), defined as such because the emotional word in the pair was positive, negative or taboo. These words were generated by collaborators or chosen from the relevant literature (Bonin et al., 2003; Hermans & De Houwer, 1994; Messina, Morais & Cantraine, 1989; Van der Goten, De Vooght & Kemps, 1999). In accordance with the original version of the dot probe task (e.g. MacLeod et al., 1986, see also Fox, 1993 and Salemink et al., 2007), all the 120 emotional pairs as well as 120 neutral pairs (i.e., as many neutral as emotional pairs) were critical pairs, as they were followed by a beep. The others were filler pairs, also considered as catch trials, since there was no beep to detect. On the basis of the database Lexique 2 (New, Pallier, Ferrand, & Matos, 2001), each category of emotional words was matched to the set of neutral words associated with them in a pair, according to the number of phonological neighbours, literary frequency and web frequency. The use of web frequency was crucial for taboo words given that it better reflects their frequency of use than the literary frequency. Hence, these matchings ensure that attentional orienting towards the spatial location of either type of word is not due to these lexical factors. According to the same criteria, we also matched all emotional words to all associated neutral words, and the two series of neutral words constituting the neutral critical pairs. Finally, we matched these four sets of material. These matching sets led to non-significant difference at 0.05. Within a

Table 1 Average standard scores obtained on the STAI-Y (Spielberger, 1983) and on the SDS (Crowne & Marlowe, 1960) and average raw scores obtained on the BDI–II (Beck et al., 1996) in Experiments 1, 2 and 3 (standard deviations are in parentheses).

STAI-Y State anxiety Trait anxiety SDS BDI-II

Exp. 1 (n = 32)

Exp. 2 (n = 24)

Exp. 3 (n = 20)

48.09 48.84 47.72 10.56

46.38 49.58 47.83 12.08

48.05 46.75 46.96 9.4

(10.80) (10.36) (22.35) (7.8)

(7.46) (10.81) (12.01) (8.54)

(6.79) (9.54) (7.64) (5.59)


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pair, the first phoneme, the syllabic structure and the phonological uniqueness point of the two words were identical. Words of the filler pairs were only matched in terms of first phoneme and syllabic structure. Four post-hoc control studies were carried out on these words or part of them. In the first post-hoc study, the 480 words constituting the critical pairs, a priori classified as neutral (360), positive (40), negative (40) and taboo (40), were presented to 24 listeners, who were asked to rate each word on a 1 (very negative) to 7 (very positive) scale for emotionality. The difference between the emotional means of the two words of each pair was calculated from these ratings. For emotional pairs of words the minimal acceptable difference was one point, whereas for neutral pairs the difference had to be smaller than one point. Following this criterion, two negative, seven positive and 14 neutral pairs were removed from analyses. In the second post-hoc study, a list of 120 words a priori classified as neutral (80) and taboo (40) was presented to 24 listeners, who were asked to rate each word on a 1 (normal) to 5 (very taboo, shocking) scale for obscenity. No word was removed from analyses on the basis of these ratings, as the confidence intervals of the two word categories did not overlap and as the minimum and the maximum values corresponding to one category did not enter into the confidence interval of the other category; however, one taboo word was removed because more than the half of the participants did not understand its shocking meaning (biroute). The characteristics of the emotional pairs that were taken into account in the statistical analyses are presented in Table 2. Since the shock value was only assessed for the taboo words and part of the neutral words, only data concerning the shock value of the taboo words are mentioned in Table 1. It should be noted that the exclusion of 24 pairs on the basis of their emotional valence or the understanding of their meaning (see above) did not affect the matching of the three categories of emotional pairs, on literary frequency, web frequency or the number of phonological neighbours. Results from the two subsequent control studies were indicative and did not serve to exclude pairs from further analyses. In the third post-hoc study, 24 participants were asked to rate the 240 words from the emotional pairs, a priori classified as neutral (120), negative (40), positive (40) and taboo (40), on a 1 (very quiet) to 7 (very arousing) arousal scale. Regarding words presented in the non-excluded pairs, statistical analysis showed that the arousal level differed between the emotional types of words, F(2, 109) = 450.29, p b 0.001, η2 = 0.894, each type differing from the others, p b 0.001 for all (Bonferroni corrected), with negative words producing the highest arousal, followed by the taboo and the positive words. For each pair we also calculated the difference in arousal level between the emotional word and its neutral associate. The effect of the type of emotional pair was significant, F(2, 109) = 258.2, p b 0.001, η2 = 0.828, each type differing from all the others at p b 0.001 (Bonferroni corrected). Negative pairs led to the greatest difference (mean: 2.04), followed by taboo (1.37) and positive pairs (−1.64).1 It is also worth noting that the shock value

1 As we developed in a normative study (Bertels, Kolinsky, & Morais, 2009), it is not surprising that positive words were judged as less arousing than their associate neutral words given that in the 7-point scale we used the “1” level depicting a very calm, relaxing feeling; the “7” level reflecting a very arousing, exciting feeling; and the “4” level referring to no particular feeling. This actually means that while neutral words were judged (on average) as not evoking any particular arousing feeling, positive words were in fact judged as more calming and relaxing than neutral words (see Table 2).

of the taboo words was positively correlated with their arousal level, r = 0.56, p b 0.001. In the fourth post-hoc study, 24 participants rated the same words as in study 3 on a 1 (unfamiliar) to 5 (very familiar) scale for familiarity. Regarding words presented in the non-excluded pairs, statistical analyses revealed that familiarity differed between the emotional types of words, F(2, 109) = 66.679, p b 0.001, η2 = 0.555, with positive words more familiar than the negative and taboo words, which also differed from each other (all p ≤ 0.001, Bonferroni corrected). We also calculated for each pair the difference in familiarity between the emotional word and its neutral associate. The effect of type of emotional pair was significant, F(2, 109) = 3.36, p = 0.04, η2 = 0.059, reflecting that positive pairs led to a greater difference than negative (0.45 vs. 0.08, p = 0.04, Bonferroni corrected), but not taboo pairs (0.34, F b 1). The difference between negative and taboo pairs did not reach significance (p N 0.10). In the beep probe task, each pair of words was presented diotically, namely with the two words constituting the pair presented simultaneously with each different member spoken through a different, lateralized, loudspeaker. Words within each pair were synchronized at their onset and offset, which was facilitated by the fact that they had the same syllabic structure, and were uttered at a constant rate. This synchronisation was made by operating very short excisions using the Protools Digidesign 6.2.2., and was perceptually evaluated by the first author. Critical pairs were followed by a 100-ms beep. Filler pairs were followed by a silence of identical duration. 2.1.3. Procedure Participants sat in front of a computer. Two loudspeakers were located at 45 cm on their left and right, with an anterior deviation of 60° in relation to the sagittal plane. Stimulus presentation and timing as well as data collection were controlled using the Psyscope button box and 1.2.5. PPC software (Cohen, MacWhinney, Flatt, & Provost, 1993) running on a Macintosh Performa 6320. Each session began with detailed instructions. Participants were told that they would hear pairs of different words, presented simultaneously, one on the left and one on the right, and that in half of the trials, a beep would be presented after the pair of words, either on the left or the right. They had to perform two tasks on each trial: firstly, to detect the beep by pressing the right key of a button box as quickly and accurately as possible with the preferred hand, without caring about its side of presentation; and secondly, to repeat as accurately as possible the word presented at a prespecified side (the same throughout the testing), to ensure they paid attention to the presented words. Each trial started with the presentation of a 750 ms fixation cross in the middle of the screen. Then, a pair of auditory words was presented. In half of the trials, immediately or 250 ms after the offset of the words (depending on the participants), a beep was presented, at the location of one of the words. The participant had 2500 ms to answer. The interval between the response and the next trial was 2000 ms. Trials were pseudo-randomly presented: a beep was presented in not more than three trials in a row, and similarly a word of the same emotional type was presented in not more than three trials in a row whatever the presentation side, and never more than in two trials in a row on the same presentation side. The experiment started with a 36-trial practice block, during which participants received feedback regarding their performance. Next, each participant was presented with five 96-trial blocks, without any feedback. Thus, a participant was presented with each pair only once insofar as assignment of a specific word to one side (e.g., “beauté–bateau” vs. “bateau–beauté”) and beep location were counterbalanced between participants.



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Table 2 Characteristics of the emotional pairs taken into account in the statistical analyses, following post-hoc control studies. n

Literary frequency

Negative pairs Negative words Neutral words Positive pairs Positive words Neutral words Taboo pairs Taboo words Neutral words

38 32.163 30.046 33 82.42 248.035 39 5.676 5.195

Web frequency

Number of phonological neighbours

Emotional valence

Shock value

Arousal

Familiarity

4261.413 9021.363

7.053 6.658

2.08 4.445

– –

5.81 3.774

3.83 3.751

15,059.057 16,487.881

10.061 11.364

6.16 4.433

– –

2.191 3.828

4.467 4.013

363.245 1385.998

8.769 7.41

2.877 4.386

2.984 –

5.052 3.686

3.549 3.209

2.2. Results Errors (misses and false alarms) were rare, 0.28% on average. Therefore, the analyses focused on RT data only. RTs on erroneous trials as well as on trials in which the participant had not correctly repeated the word (in total, 11.18% of the observations) were excluded from further analyses. This was also the case for RTs on the 24 pairs for which (a) the emotional word did not differ considerably on emotional valence from the neutral word; or (b) one neutral word did differ on emotional valence from the other neutral word of the pair; or (c) the shocking meaning was not straightforward (see Method).2 Table 3 displays the mean correct RTs. Firstly, we examined whether the presence of an emotional word of a particular valence affected the response to the beep. For this purpose, a 2 (interval length: short/long) × 2 (repetition side: left/ right) × 4 (type of emotional pair: neutral/negative/positive/taboo) × 2 (beep location: left/right) repeated measures analysis of variance (ANOVA) design was applied on correct response latencies. The type of emotional pair and the beep location were within-subject factors, interval length and repetition side were between-subject factors. The only significant factor was the type of emotional pair, F(3, 84) = 17.8, p b 0.01, partial η2 = 0.389: taboo pairs led to significantly longer RTs (463 ms, on the average) than neutral (416 ms), positive (415 ms) and negative (414 ms) pairs respectively, all p b 0.01 (Bonferroni corrected). No other comparison was significant, all p N 0.10. The interaction between type of emotional pair and interval length did not reach significance, F b 1. The second important point was to assess whether emotional words led to attentional biases, namely if they facilitated the detection of the beep when this was presented at the same spatial location (in spatially congruent trials) as the emotional word in comparison to the situation where it was presented at the opposite spatial location (in spatially incongruent trials). As in other studies that looked for attentional biases linked to the emotional valence of the stimuli, the analyses only took the results on emotional pairs into account, given that, by definition, emotional word location is not available for neutral pairs. A 2 (interval length: short/long) × 2 (repetition side: left/ right) × 3 (type of emotional pair: positive/negative/taboo) × 2 (beep location: left/right) × 2 (emotional word location: left/right) repeated measures ANOVA design was applied on response latencies. Interval length and repetition side were between-subject factors, the other variables were within-subject factors. The only main effect that reached significance was the type of emotional pair, F(2, 56) = 18.46, p b 0.001, partial η2 = 0.397. As with the previous analysis, Bonferroni

2 Note that results from the statistical analyses on the whole set of data were similar to the ones obtained after exclusion of these pairs. In particular, the four-way interaction between type of emotional pair, beep location, emotional word location and interval length was significant, F(2, 56) = 4.37, p b 0.02, partial η2 = 0.135.

adjusted post-hoc comparisons showed that taboo pairs led to longer RTs than negative and positive pairs, both p b 0.001, which did not differ between each other, p N 0.10. More crucially, there was a significant three-way interaction between type of emotional pair, beep location and emotional word location, F(2, 56) = 5.07, p b 0.01, partial η2 = 0.153, superimposed by a significant four-way interaction between type of emotional pair, beep location, emotional word location and interval length, F(2, 56) = 3.27, p b 0.05, partial η2 = 0.104. Considering each interval condition separately, we found the effect of type of emotional pair to be significant in both, F(2, 28) = 14.27 and 6.53, both p b 0.01, partial η2 = 0.505 and 0.318. In contrast, the three-way interaction between type of emotional pair, beep location and emotional word location was significant in the short interval condition, F(2, 28) = 7.97, p = 0.002, partial η2 = 0.363, but not in the long one, F b 1. In the short interval condition, we analysed separately the data for each type of emotional pair, given that we predicted the occurrence of attentional biases with taboo and negative pairs, but not with positive pairs. The interaction between beep location and emotional word location was significant for the taboo pairs, F(1, 14) = 9.46, p b 0.01, partial η2 = 0.403, but not for the negative pairs, F(1, 14) = 1.8, p N 0.10, partial η2 = 0.114; for positive pairs there was only a trend, F(1, 14) = 3.7, p = 0.08, partial η2 = 0.208. This interaction reflects the fact that, when the taboo word was right-presented, participants detected the beep faster when this was right-presented (434 ms) than when it was left-presented (515 ms), p b 0.001 (Bonferroni corrected). No effect was observed when the taboo word was left-presented, p N 0.10 (see Fig. 1). Thus, the attentional bias reflected by the RT difference (81 ms)

Table 3 Mean correct detection times observed in Experiment 1 for all types of pairs (standard errors are in parentheses). Type of emotional pair Beep and emotional word locations Short interval condition Beep Left Emotional word Left Emotional word Right Beep Right Emotional word Left Emotional word Right Average Long interval condition Beep Left Emotional word Left Emotional word Right Beep Right Emotional word Left Emotional word Right Average

Neutral

Negative

Positive

Taboo

448 (28) 402 (17)

435 (21) 407 (19)

468 (27) 515 (29)

429 (23) 431 (24) 427 (18)

407 (22) 431 (29) 420 (18)

489 (33) 434 (27) 477 (24)

394 (16) 397 (20)

409 (17) 398 (20)

428 (18) 459 (33)

406 (25) 403 (22) 400 (18)

410 (23) 422 (33) 410 (18)

444 (28) 467 (37) 450 (24)

436 (21)

424 (20)

430 (17)

409 (17)

395 (21)

402 (17)


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Fig. 1. Target detection latencies observed for taboo pairs in Experiment 1, in the short interval length condition, as a function of the emotional word and beep locations.

between the spatially incongruent and congruent taboo trials was restricted to the condition in which the taboo word was rightpresented. This bias was not correlated with any of the scores on the personality questionnaires (STAI-state: r = −0.15; STAI-trait: r = 0.11; BDI–II: r = −0.05; SDS: r = 0.07, all p N 0.50). Moreover, the attentional bias linked to right-presented taboo words in the short interval condition was significantly larger than the non-significant biases associated with right-presented negative and positive words (−30 and −24 ms, respectively), t(15) = 3.753 and 4.123, both p b 0.005 (Bonferroni corrected). It is of theoretical interest to consider on which spatial attentional orienting component(s) taboo words had an effect. A positive attentional bias like the one observed here for right-presented taboo words (i.e., a positive difference between RTs on incongruent and congruent trials for these words) could be due either to vigilance to the taboo words, namely an effect on the engagement component of attentional orienting, or to difficulties in disengaging attention from these words once attention has been normally engaged. In the former case, the attentional bias would result from a RT advantage on congruent compared to incongruent trials, whereas in the latter case it would proceed from increased RTs on incongruent trials. However, merely comparing RTs on congruent and incongruent trials does not disentangle these possibilities given the absence of a baseline in the emotional trials. To solve this problem, Koster, Crombez, Verschuere, and De Houwer (2004) proposed to use the neutral trials (i.e., trials in which both words are emotionally neutral) as baseline and to compare them systematically with the RTs on congruent and incongruent trials, but this approach has been recently criticized (Mogg, Holmes, Garner, & Bradley, 2008). Given that neutral trials do not, by definition, contain emotional words, these authors argued that potential non-spatial interference effects of emotional words could contribute to the RT difference between neutral and spatially (in)congruent trials. As such general, non-spatial effects of taboo words occurred in the present experiment, the RT difference with neutral words would not be a pure index of the attentional orienting processes influenced by the presentation of taboo words. Nevertheless, the specific results obtained here allow us to use another baseline, to which the criticism addressed by Mogg et al. (2008) does not apply. Since attentional biases towards taboo words were only observed when the taboo word was right-presented, RTs on left-presented taboo words can serve as a baseline to determine whether participants were particularly vigilant to right-presented taboo words or, instead, had difficulties to disengage from these words. Attentional vigilance to right-presented taboo words would be reflected in RTs on right-located beeps presented after rightpresented taboo words being shorter than the average RTs on leftand right-located beeps presented after left-presented taboo words.

To put it in a formula: x̅ RTs taboo R-beep R b x̅ RTs taboo L (beep L&R). In contrast, difficulties to disengage attention from right-presented taboo words would be reflected in increased RTs on left-located beeps following right-presented taboo words compared to RTs on beeps following left-presented taboo words, i.e. x̅ RTs taboo R-beep L N x̅ RTs taboo L (beep L&R). Given that general, non-spatial effects of taboo words do not depend on the location of the taboo word in the pair, any difference between these RTs can only be allocated to spatial effects of right-presented taboo words. As can be seen in Fig. 1, in the short interval condition of the present experiment, RTs on trials in which both the taboo word and the beep were right-presented were shorter than RTs on trials in which the taboo word was left-presented (434 vs. 479 ms, t(15) = 2.35, p = 0.035). In contrast, RTs on trials in which the right-presented taboo word was followed by a left-located beep did not differ from RTs on trials in which the taboo word was left-presented (515 vs. 479 ms, t (15) = 1.75, p = 0.10). Hence, these results suggest that attention would be engaged preferentially to the spatial location of a rightpresented taboo word relative to the spatial location of the neutral word presented simultaneously in the pair. 2.3. Discussion In Experiment 1, participants had to detect a beep as quickly as possible and to repeat on each trial a word presented at a prespecified side. We observed an attentional bias: the detection of a beep was faster if it appeared at the same spatial location as a just presented taboo word than if it appeared at the opposite location. As predicted, this attentional bias was observed only when the beep followed immediately the presentation of the pair of words, suggesting that the phenomenon is very fleeting. Moreover, this only held true when the taboo word originated from the right side of the listener, a specificity that allowed us to establish that the observed attentional bias reflected attentional vigilance towards taboo words rather than difficulties to disengage from these words. In addition to producing an attentional bias, taboo words also seem to lead to a general, non-spatial effect. Indeed, whatever the interval length this time, taboo pairs yielded longer RTs to the beep than the other types of pairs, be they emotional or neutral ones. Contrary to our prediction, there was no attentional bias linked to the spatial source of negative words. However, in this experiment, the concurrent repetition task may have monopolized some attentional resources, making it difficult for negative words to facilitate selectively the detection of a same-side beep. This explanation was checked in Experiment 2 by removing the repetition task. 3. Experiment 2: Beep probe detection This experiment was similar to Experiment 1, except that participants only had to detect the beep, without having to pay attention to one side of presentation in order to repeat the presented word. Moreover, given the results of the first experiment, we only used the short interval condition for all participants. In addition to reducing the cognitive load of the task, the present experiment could also help us to discard an alternative explanation of the effects observed on taboo words in Experiment 1. Indeed, in the former experiment, the observed bias and delayed RTs could be linked to the participants' emotional reaction to the requirement of repeating a taboo word in front of the experimenter, in a similar way as the taboo nature of the verbal response made by the subject could be responsible for the higher recognition thresholds and galvanic skin response observed for those words (Zajonc, 1962). If this were the case, no specific effect of taboo words should be observed in the present experiment. On the contrary, if the effects observed in Experiment 1 reflected attentional influences of taboo words, the same attentional



bias and delayed RTs should be observed here, because the present situation no longer requires a verbal response.

Table 4 Mean correct detection times observed in Experiment 2 for all types of pairs (standard errors are in parentheses). Type of emotional pair

3.1. Method 3.1.1. Participants Participants were 27 undergraduate students of the Université Libre de Bruxelles (24 women; 3 left-handed), ranging in age from 18 to 25 (mean: 18.97). They were given course credits for their participation. The results of three participants (3 women; 1 lefthanded) were discarded from further analyses, because their RTs were superior to two standard deviations above the mean. All participants had spoken French for at least 10 years. Average scores on three personality questionnaires evaluating anxiety and depression levels as well as willingness to be socially desirable are presented in Table 1. 3.1.2. Material and apparatus The material and the apparatus were the same as in Experiment 1. 3.1.3. Procedure The procedure was exactly the same as in Experiment 1 except that there was no repetition task and we only used the short interval condition: for all participants on critical pairs, the beep appeared immediately after the offset of the words. 3.2. Results Errors (misses and false alarms) were again very infrequent (0.2%, on the average) so that the analyses focused only on the RT data. As in Experiment 1, RTs on erroneous trials as well as RTs on 24 pairs were excluded from the analysis (see Method of Experiment 1).3 Table 4 displayed the mean correct RTs. As in the previous experiment, we first applied a 4 (type of emotional pair: neutral/negative/positive/taboo) × 2 (beep location: left/right) repeated measures analysis of variance (ANOVA) design on correct response latencies to examine whether the presence of an emotional word in the pair influenced the processing of an ensuing beep. The type of emotional pair and the beep location were withinsubject factors. The type of emotional pair was the only significant factor, F(3, 69) = 3.51, p = 0.02, partial η2 = 0.132. Bonferroni adjusted post-hoc comparisons showed that RTs on taboo pairs (294 ms) tended to be longer than RTs on negative pairs (286 ms), p = 0.09. This was not the case for taboo pairs relative to positive ones (297 ms), p N 0.10. The same effect was observed in the 3 (type of emotional pair: negative/positive/taboo) × 2 (beep location: left/right) × 2 (emotional word location: left/right) repeated measures ANOVA design applied on correct response latencies, F(2, 46) = 4.41, p b 0.02, partial η22 = 0.161. Taboo pairs led to significantly longer RTs than negative pairs, p b 0.05. No difference was observed for taboo pairs compared to positive ones, p N 0.10 (Bonferroni corrected). No other effect or interaction was significant. In particular, the three-way interaction between type of emotional pair, beep location and emotional word location felt short of significance, F(2, 46) = 2.71, p = 0.078, partial η2 = 0.105. Nevertheless, Bonferroni adjusted comparisons revealed that, as in Experiment 1,

3 Results from the statistical analyses on the whole set of data were similar to the ones obtained without the excluded pairs: the three-way interaction between type of emotional pair, beep location and emotional word location was not significant, F(2, 46) =2.29, pN 0.10, partial η2 = 0.09. Nevertheless, right-presented beeps following right-presented taboo words tended to lead to shorter RTs than left-presented beeps following right-presented taboo words, p= 0.065 (Bonferroni corrected).

7

Beep and emotional word locations

Neutral

Beep Left Emotional Emotional Beep Right Emotional Emotional Average

297 (12) word Left word Right

Negative

Positive

Taboo

292 (11) 282 (11)

301 (15) 294 (14)

294 (13) 303 (14)

285 (13) 286 (12) 286 (12)

291 (14) 301 (13) 297 (14)

295 (14) 286 (12) 294 (13)

294 (11) word Left word Right 295 (12)

when the taboo word was right-presented, participants detected the beep faster when it was also right-presented than when it was leftpresented (286 vs. 303 ms), p = 0.05. No difference was observed when the taboo word was left-presented, p N 0.10 (see Fig. 2). These comparisons were not significant for negative and positive pairs, all p N 0.10. We thus observed an attentional bias linked to taboo words (17 ms) when these were right-presented. This bias was not correlated with any of the scores on the personality questionnaires (STAI-state: r = 0.04; STAI-trait: r = −0.016; BDI–II: r = −0.076; SDS: r = −0.057, all p N 0.50). Moreover, the attentional bias linked to right-presented taboo words was significantly larger than the non-significant bias associated with right-presented positive words (−7 ms), t(23) = 2.969, p b 0.015 (Bonferroni corrected). However, the difference between the attentional biases linked to right-presented taboo and negative words (−4 ms) was not significant, p N 0.10. Given that, as in Experiment 1, an attentional bias was only observed when the taboo word was right-presented, we used RTs on trials in which taboo words were left-presented as a baseline in order to determine which spatial orienting component was affected by the presentation of a right-presented taboo word. However, RTs on trials in which both the taboo word and the beep were right-presented did not significantly differ from RTs on trials in which the taboo word was left-presented (286 vs. 295 ms, t(23) = 1.36, p N 0.10). Similarly, RTs on trials in which the right-presented taboo word was followed by a left-located beep did not differ from RTs on trials in which the taboo word was left-presented (303 vs. 295 ms, t(23) = 1.16, p N 0.10). Hence, these results do not allow us to conclude about the nature of the spatial component affected by the presentation of taboo words.

Fig. 2. Target detection latencies observed for taboo pairs in Experiment 2, as a function of the emotional word and beep locations.


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3.3. Discussion As in Experiment 1, we observed an attentional bias linked to the taboo nature of words. Taboo pairs also yielded longer RTs than negative pairs. Given that participants did not now have to repeat words, the effects observed in Experiment 1 cannot be attributed to an emotional reaction when repeating a taboo word. The fact that these effects were larger in Experiment 1 than in the present experiment is most probably due to the longest RTs associated to the double task condition of our first experiment. Consistent with this idea, for Experiments 1 and 2 considered together, we observed a significant correlation between attentional biases linked to right-presented taboo words and the average RTs, r = .461, p b 0.01. Given that no attentional bias was observed for negative words, contrary to what we supposed, it does not seem that the presence or absence of such an effect of these words is, at least exclusively, related to the extent to which attentional resources are mobilized by a concurrent task. It may be the case that a spatial dimension needs to be involved, in addition to a low cognitive load, in order to observe attentional biases towards the spatial location of negative words. Indeed, as already mentioned in the Introduction of Experiment 1, some authors argued that spatial attentional orienting towards the location of a single peripheral cue would only occur when a spatial representation is activated by the task (Rhodes, 1987; Schmitt et al., 2000; Spence & Driver, 1994). Supporting this idea, they observed validity effects (i.e. spatial attentional orienting) with a localization task but not with a detection task. Considering that the presence of an emotional word in the pair can act as a single peripheral cue, one possibility is that attentional orienting towards its spatial location (i.e. attentional biases) occurs more easily if a localization task is used, because this task strongly activates a spatial representation. This possibility was investigated in Experiment 3. 4. Experiment 3: Beep probe localization This experiment was exactly the same as Experiment 2, except that participants had to localize the beep when it was presented, instead of simply detecting it. Word repetition was not required, so that, contrary to Experiment 1, participants' attentional resources were not mobilized by a concurrent task. In doing so, we predicted that we would observe not only attentional biases linked to the taboo nature of the words (as was the case in the two previous experiments) but also attentional biases linked to the spatial location of negative words. 4.1. Method 4.1.1. Participants Participants were 23 undergraduate students of the Université Libre de Bruxelles (23 women; 3 left-handed), ranging in age from 18 to 22 (mean: 19.35). They were given course credits for their participation. The results of three subjects (3 women, 1 left-handed) were discarded from further analyses because their error rate was superior to two standard deviations above the mean. All participants had spoken French for at least 10 years. Average scores on three personality questionnaires evaluating anxiety and depression levels as well as willingness to be socially desirable are presented in Table 1. 4.1.2. Material and apparatus The material and the apparatus were the same as in Experiments 1 and 2. 4.1.3. Procedure The procedure was exactly the same as in Experiment 2 except that the participants had to localize the beep as quickly and accurately

Table 5 Mean correct localization times observed in Experiment 3 for all types of pairs (standard errors are in parentheses). Type of emotional pair Beep and emotional word locations

Neutral

Beep Left Emotional Emotional Beep Right Emotional Emotional Average

358 (18) word Left word Right

Negative

Positive

Taboo

349 (18) 359 (19)

359 (19) 360 (21)

374 (23) 384 (22)

352 (16) 335 (16) 349 (17)

329 (15) 354 (18) 350 (18)

367 (20) 348 (19) 368 (20)

349 (17) word Left word Right 353 (17)

as possible by pressing the left or right key of a button box. Again, there was no repetition task.

4.2. Results As in Experiments 1 and 2, errors (misses, false alarms and wrong localizations) were very infrequent (0.4%, on the average) so that the analyses focused only on the RT data. Erroneous responses were excluded from further analyses. Also, we excluded from the analyses the RTs on 24 pairs (see Method of Experiment 1).4 Mean correct RTs are presented in Table 5. We first applied a 4 (type of emotional pair: neutral/negative/ positive/taboo) × 2 (beep location: left/right) repeated measures analysis of variance (ANOVA) on response latencies. Both variables were treated as within-subject factors. The effect of type of emotional pair was significant, F(3, 57) = 8.57, p b 0.01, partial η2 = 0.311, with taboo pairs leading to overall longer RTs (368 ms) than neutral (353 ms), positive (350 ms) and negative (349 ms) pairs, all p b 0.03 (Bonferroni corrected). Also significant was the effect of beep location, F(1, 19) = 9.48, p b 0.01, partial η2 = 0.333, which reflects the fact that participants localized the beep faster when it was right-presented than when it was left-presented (348 vs. 363 ms, respectively). Further analyses only took the results on emotional pairs into account. A 3 (type of emotional pair: positive/negative/taboo) × 2 (beep location: left/right) × 2 (emotional word location: left/right) repeated measures ANOVA design was applied on response latencies. All variables were within-subjects factors. The main effects that reached significance were the type of emotional pair, F(2, 38) = 9.32, p = 0.001, partial η2 = 0.329, and the beep location, F(1, 19) = 9.64, p b 0.01, partial η2 = 0.336, both reflecting the same differences as in the analysis including neutral words (see above). The three-way interaction between the type of emotional pair, beep location and emotional word location was also significant, F(2, 38) = 6.01, p = 0.005, partial η2 = 0.24. To further examine this interaction, we analyzed separately the results for each type of emotional pair. The interaction between beep location and emotional word location was significant for the taboo and negative pairs, F(1, 19)=4.45, pb 0.05, partial η2 =0.19 and F(1, 19)=9.33, pb 0.01, partial η2 =0.329, not for the positive pairs, F(1, 19)=2.92, pN 0.10, partial η2 =0.133. The interaction between beep location and emotional word location for taboo pairs reflected the fact that when the taboo word was right-presented, participants localized a right-

4 Note that results from the statistical analyses including the excluded pairs were similar to those obtained without these: the three-way interaction between type of emotional pair, beep location and emotional word location is significant, F(2, 38) = 5.25, p = 0.01, partial η2 = 0.216.



presented beep faster (348 ms) than a left-presented beep (384 ms), p=0.004. There was no difference when the taboo word was leftpresented, pN 0.10 (see Fig. 3a). This was also the case for negative pairs: when the negative word was right-presented, participants localized a right-presented beep faster (335 ms) than a left-presented one (359 ms), p=0.002, while there was no difference when the word was left-presented, pN 0.10 (see Fig. 3b). We thus observed attentional biases linked to taboo (36 ms) and to negative (24 ms) words when they were right-presented. None of these attentional biases was correlated with any of the scores on the personality questionnaires (For taboo words: STAI-state: r = 0.07, STAI-trait: r = 0.23, BDI-II: r = −0.13, SDS: r = −0.10, all p N 0.30; for negative words: STAI-state: r = −0.06, STAI-trait: r = 0.15, BDI–II: r = 0.21, SDS: r = −0.30, all p N 0.15 ). The difference between the attentional biases linked to rightpresented negative and taboo words and the attentional bias linked to right-presented positive words (6 ms) did not reach significance, both p ≥ 0.10 (Bonferroni corrected). As expected, the biases linked to rightpresented negative and taboo words did not differ from each other, t b 1. As can be seen in Fig. 3a, RTs on trials in which both the taboo word and the beep were right-presented were shorter than RTs on trials in which the taboo word was left-presented (348 vs. 370 ms, t(19) = 2.34, p = 0.03). In contrast, RTs on trials in which the right-presented taboo word was followed by a left-located beep did not differ from RTs on trials in which the taboo word was left-presented (384 vs. 370 ms, t(19) = 1.2, p N 0.10). Similarly, as depicted by Fig. 3b, RTs on trials in which both the negative word and the beep were right-presented were shorter than RTs on trials in which the negative word was leftpresented (335 vs. 350 ms, t(19) = 2.34, p = 0.03). On the contrary, no RT difference was found between trials in which a left-located beep

Fig. 3. a and b. Target localization latencies observed in Experiment 3, as a function of the emotional word and beep locations, for taboo (a) and negative (b) pairs, respectively.

9

followed a right-presented negative word and trials in which a negative word was left-presented (359 vs. 335 ms, t(19) = 1.194, p N 0.10). 4.3. Discussion As in Experiments 1 and 2, we observed that participants responded faster to a beep presented at the same location as a taboo word than presented at the same location as a neutral word. Again, this attentional bias was only observed when the taboo word was right-presented. Moreover, as in Experiment 1, results suggest that participants did not have difficulties in disengaging attention from taboo words but were, rather, particularly vigilant to these words. This spatial effect of taboo words thus appears to be robust. In addition, as in the previous experiments, trials in which a taboo word was presented led to overall longer RTs to a following beep than other types of trials, whatever the side of presentation of the beep. Importantly, in Experiment 3, an attentional bias was also observed towards negative words. As with the attentional biases observed for taboo words, this bias for negative words was only observed when the emotional word was right-presented and most probably reflects attentional vigilance towards these words. 5. General discussion While the distinction between the “what” and the “where” auditory subsystems is largely accepted (e.g., Kubovy & Van Valkenburg, 2001), the functional link between these subsystems has been relatively neglected. Yet such a link would be advantageous for ecological adaptation: if the identification of an auditory object that conveys emotional information leads to activate the information about its spatial location, then one would be in a better attentional state to react to subsequent auditory information coming from the same spatial location. In the present study, we investigated the existence of a functional link between the auditory “what” and “where” subsystems by examining the influence of the emotional content of spoken words, linked to the “what” subsystem, on the spatial orienting of auditory attention, relying on the “where” subsystem. This was done by using a specific kind of cuing situation (Posner, 1980), actually an auditory adaptation of the attentional deployment task (MacLeod et al., 1986) in which a pair of spoken words — one potentially emotional — was followed by a beep target. Considering that the presence of an emotional word of the pair can act as a single peripheral cue, we expected to observe spatial congruency effects, namely attentional biases linked to the spatial location of taboo and negative words, but no specific effect of positive words was anticipated. Moreover, according to Kinsbourne's (1970) theory, as the presentation of verbal material could prime the left hemisphere, leading to an orientational bias to the contralateral hemifield, and following the idea that an emotional word catches more attentional resources than its paired neutral word (therefore activating to a greater extent the hemispheric contralateral to its side of presentation), we predicted attentional biases linked to the emotional valence of the words to occur largely when the emotional word was right-presented. An overview of the experiments and their associated results is presented in Table 6. Crucially, in addition to non-spatial inhibitory effects of taboo words, attentional biases linked to the spatial location of taboo and negative spoken words were observed. Namely, participants responded faster to a beep presented at the same spatial location as the taboo or negative word of the pair than to the neutral word. In particular, attentional biases towards taboo words were consistently observed in three experiments, regardless of whether attention to the words and a spatial response were required or not. In contrast, attentional biases towards negative words were only observed when the attentional load was low, that is when attention to the words was not required, and when participants had to indicate


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Table 6 Overview of the three experiments. Experiment Interval Task(s) length (ms)

Results Spatial effects Non-spatial effects (attentional biases)

1

0

250

2

0

3

0

Beep detection then repetition Beep detection then repetition Beep detection Beep localization

Right taboo words

RTs taboo N RTs negative, positive, neutral words

–

RTs taboo N RTs negative, positive, neutral words

Right taboo words

RTs taboo N RTs negative words RTs taboo N RTs negative, positive, neutral words

Right taboo and negative words

emotional trials exclusively. Hence, if there were any influence of the predictive nature of the occurrence of an emotional word, this influence marred all these reaction times, making them comparable and warranting that any difference between them is due to their specific emotional content. Finally, in Experiment 3, although target beeps were also presented more often after emotional than after neutral trials, the participants' task was to localize the beep. Thus, an adequate response could not be prepared on the basis of the occurrence of an emotional word in the pair, given that the location of the emotional word of the pair (left/right) was not predictive of the location of the beep. Still, we observed results similar to those of Experiments 1 and 2, indicating that the predictability of the relation between the presence of an emotional word and the occurrence of the beep, even if it were noted by the participants (which is unwarranted), could not be responsible for the observation of spatial and non-spatial effects for taboo and negative words, respectively.

5.1. Attentional biases to taboo words the spatial location of the beep by pressing one of two response buttons (as in Experiment 3). Importantly, these attentional biases occurred only when the emotional word of the pair was rightpresented, which is coherent with Kinsbourne's (1970) theory. Notably, these attentional biases were observed in unselected volunteers and were not correlated with any of the scores in the personality questionnaires. Our data are thus in accordance with the idea of an emotion-dependent functional link between the “what” and the “where” auditory subsystems. Before discussing the conditions under which this link is observed, a relevant methodological point should be addressed. In all experiments, we adopted MacLeod et al.'s (1986) original design of the dot probe task that was largely used in other visual studies (e.g., Fox, 1993; Salemink et al., 2007). As previously commented on by Mogg and Bradley (1998, 1999), in this design, the occurrence of an emotional word is predictive of the occurrence of the target. More specifically, in the present experiments the beep was presented after all emotional pairs but only after one third of the neutral pairs. Nevertheless, the present results cannot be accounted for by the predictability of the occurrence of the beep. As a matter of fact, in the present study, we used several types of emotional words (i.e., negative, positive, and taboo). Thus, if the predictability of the occurrence of the beep following an emotional word were responsible for the observed spatial and non-spatial effects, then these effects would be observed for all emotional words. On the contrary, when a detection task was used (Experiments 1 and 2), only taboo words influenced the spatial orienting of attention, only negative words led to non-spatial effects, and positive words did not elicit either type of effect. Moreover, attentional biases were only observed when the emotional word was right-presented in the linguistic pair. This cannot be a consequence of the fact that the presence of an emotional word in the pair was predictive of the occurrence of the beep, given that the side of presentation of the emotional word was unpredictable. Indeed, it does not seem reasonable to admit that listeners only attended to taboo words on their right side or that they decided that only taboo words presented on their right side were predictive of the occurrence of the beep. However, even if the present results eliminate the possibility that the attentional effects would result from the detection of the predictability of the occurrence of the target, further studies should rather present a to-belocalized beep on each (emotional or neutral) trial, as it is often the case in dot probe studies (e.g., Mogg, Bradley, De Bono, & Painter, 1997; Mogg & Bradley, 1999). It ought also to be taken into account that the occurrence of attentional biases linked to the presentation of a specific type of emotional word was investigated comparing reaction times to

An attentional bias linked to the spatial source of right-presented taboo words was consistently observed in three experiments. This is consistent with previous results from visual studies that used the taboo variant of the emotional Stroop task (the taboo Stroop task), in which it has been repeatedly shown that healthy, unselected participants took longer to name the ink colour of taboo words compared to neutral words (MacKay & Ahmetzanov, 2005; MacKay et al., 2004; Siegrist, 1995; Taylor, Kornblum, Lauber, Minoshima, & Koeppe, 1997). These interference effects are generally considered to be attentional biases. However, as in the Stroop setting the two dimensions of the stimulus, relevant and irrelevant for the task (the ink colour and the emotional valence, respectively), are part of the same stimulus, no spatial attentional shift is expected to occur. Given that taboo words have never been used in paradigms involving spatial attentional orienting such as the dot probe task (MacLeod et al., 1986) and the emotional cuing paradigm (Stormark, Nordby, & Hugdahl, 1995), the present results extend the findings already reported in the Stroop situation for visually presented taboo words by showing spatial attentional biases for auditorily presented taboo words. In addition, in comparison to most visual studies using taboo words (but see Nielsen & Sarason, 1981), the present results may have more ecological validity, given that such words are more common in oral than in written language. We also examined, more specifically, on which spatial attentional orienting component(s) taboo words had an effect. For this purpose, we compared RTs on congruent and incongruent rightpresented taboo trials with RTs on left-presented taboo trials (acting as baseline, given that no attentional bias was observed on these trials). In Experiments 1 and 3, we observed an RT advantage for congruent right-presented taboo trials compared to baseline left-presented taboo trials, but found no difference between RTs on incongruent right-presented taboo trials and left-presented taboo trials. This is more consistent with the hypothesis of an attentional vigilance towards taboo words than with the idea of difficulties to disengage attention from these words once attention has been normally engaged. Attention would be engaged preferentially to the spatial location of a right-presented taboo word relative to the spatial location of the neutral word presented simultaneously in the pair. However, further studies using a different methodology should confirm these findings. Indeed, as suggested by an anonymous Reviewer, the fact that no attentional bias was observed for left-presented taboo words does not ensure that they did not have any influence on RTs (e.g., they could be antagonistic). As such, RTs on emotional trials do not appear to be the most proper baseline.



Further work should aim at clarifying the basis of this attentional vigilance towards spoken taboo words. Nevertheless, it is worth noting that the set of taboo words we used in the experiments was matched in literary and web frequencies with the set of neutral words with which they were associated in the pairs. The infrequent nature of taboo words is therefore unlikely to be responsible for the occurrence of the attentional bias. Moreover, one of the post-hoc control studies confirmed that our taboo words were not less familiar than the associated neutral words (see Method section of Experiment 1). Rather, two potential factors could have held the participants' attention: the arousing and shocking nature of the taboo words. According to various studies, arousal would account for the observed effects on attention (e.g., Anderson, 2005; Schimmack, 2005) as well as on memory (e.g., Buchanan, Etzel, Adolphs, & Tranel, 2006; Kensinger & Corkin, 2003; Mather et al., 2006). Using the attentional blink paradigm, recent studies showed preferential attentional processing of taboo stimuli (Arnell, Killman, & Fijavz, 2007; Mathewson, Arnell, & Mansfield, 2008; Most, Smith, Cooter, Levy, & Zald, 2007), and some researchers argued that the arousal nature of these stimuli in fact influences their encoding in memory (Arnell et al., 2007; Mathewson et al., 2008). However, the whole set of data does not seem to support the idea that arousal is the only factor leading to attentional capture: in Mathewson et al.'s (2008) study, the threatening words used in the experiments were as arousing as taboo words, but had no effect. Hence, even if arousal is a crucial dimension, taboo words seem to have a particular quality which accounts for this different effect. Although our study was not initially designed to assess the impact of arousal, two results of our post-hoc control study (see Method section of Experiment 1) enable us to discard this factor as the main basis of the observed effects. Firstly, no correlation was found between the attentional bias when the emotional word was rightpresented and the difference in arousal between the emotional and the neutral word of the pair in any of the experiments (all p N 0.10). Hence, this difference does not seem to be a good predictor of the size of the attentional bias (highest R2: 0.041). This was the case both when the correlation analyses included all emotional words irrespective of valence and when separate correlation analyses were performed for positive, negative and taboo words. Secondly, the arousal level of taboo words was lower than the arousal level of the negative words used in the experiments. Also, the difference in arousal between the emotional and the neutral word of the pair was lower for taboo than for negative pairs. If arousal were the crucial factor in the occurrence of the effect, we should have observed robust attentional biases towards negative words as well. Thus, rather than arousal, it seems that it is their shocking quality (perhaps combined with arousal) that is the relevant factor of the attentional bias they provoke. As MacKay et al. (2004) suggested, the particular type of emotional reaction could play a crucial role in the culmination of the process. For example, taboo words may create sexual arousal or embarrassment, which would be responsible for this particular involvement of attentional processes. Attentional biases linked to taboo words appear to be shortlived, suggesting that the activation of the “what-where” connections would be transient. As a matter of fact, in Experiment 1, attentional biases to taboo words were only observed when the interval between the offset of the words and the onset of the beep was null, not when it was 250 ms long. The fact that an attentional bias only occurs towards events (here, the beep) which are concomitant (e.g., in the emotional Stroop task) or which immediately follow the emotional information (taboo, in our case) seems adaptive: given their transitory nature, emotional auditory stimuli would create reactions having an influence on the processing of immediately subsequent events, not on the processing of later ones. This would be the case particularly when subsequent events are not emotional and when they have no other

11

link with the emotional information than spatial location. However, as the effect of two intervals were compared only in Experiment 1 (given that no attentional bias was observed with the long one) and as no other study using an attentional deployment task compared different conditions of intervals between the pair of words and the probe, our observation remains isolated, and hence should be considered with caution. 5.2. Attentional biases towards negative words In addition to attentional biases to right-presented taboo words, we also observed attentional biases to right-presented negative words in Experiment 3, but this was not the case in Experiments 1 and 2. Therefore, the attentional bias to negative words appears to be less robust than the attentional biases to taboo words or, instead, to occur under specific conditions. A crucial factor could be cognitive load, with spatial effects of the negative valence observable only under low-load conditions. Indeed, in Experiment 3, the average RTs were far shorter than in Experiment 1 (344 vs. 439 ms). The idea that task-irrelevant emotional stimuli are subject to the effects of processing load (as are neutral stimuli, cf. Lavie, 1995) is supported by studies showing that brain responses usually observed to emotional stimuli disappear when cognitive load increases (e.g., Doallo, Holguín, & Cadaveira, 2006; Mitchell et al., 2007; Pessoa, McKenna, Gutierrez, & Ungerleider, 2002; Pessoa, Padmala, & Morland, 2005). Also, at the behavioural level, interference effects of emotional stimuli on performance vanish with the increase of task demands, suggesting that interference only occurs when sufficient resources are available to process task-irrelevant emotional information (Okon-Singer, Tzelgov, & Henik, 2007; Smith Erthal et al., 2005). Similarly, in our study, participants were particularly vigilant to negative stimuli when cognitive load was low (Experiment 3), not at all when it was high (Experiment 1). However, cognitive load does not explain the whole phenomenon. As a matter of fact, no attentional bias to negative words was observed in Experiment 2, although participants only had to detect the presence of a beep. As already developed in the Discussion section of Experiment 2, one possibility is that negative words would only influence the spatial orienting of auditory attention when the spatial location of the beep is task-relevant, as was the case in Experiment 3, but not in Experiment 2. Actually, when negative words are presented, the involvement of a spatial orienting component would be critical to permit “what”-related dimensions to influence “where”related ones, in addition to a low cognitive load. The “where” subsystem would be influenced by the “what” subsystem that detects a negative emotional content only when it is previously activated, namely when it is somehow relevant to the participant's goal. These assumptions require verification in further studies. Interestingly, as was the case with taboo words, attentional biases to right-presented negative words would be due to participants being particularly vigilant to these words: when presented together with a neutral word, attention would be oriented preferentially to the spatial location of the negative word. 5.3. Laterality effects in attention Following Kinsbourne's (1970) theory, we assumed that the use of verbal material would prime the left hemisphere, leading to orientational biases to the contralateral side (the right one). Ordinarily, one would expect left rather than right orientational biases, given the emotional nature of the words and the fact that emotions are processed in the right hemisphere (e.g., Bryden & MacRae, 1989). However, this assumption comes from studies in which participants had to process the emotional dimension of the stimuli, which was not the case in our experiments. In Experiments 2


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and 3 they were not even required to process the words at all. Moreover, not all words were emotionally charged. Hence, the mere presentation of words seems to activate the left hemisphere, and this activation could have been reinforced by the expectations of the participants as to the verbal nature of the major part of the material, leading to a right orientational bias. This idea resonates with the earlier findings of Demakis and Harrison (1994) who showed that the rehearsal of affective words primed the left hemisphere, as neutral words did, suggesting that even affective words are processed by the left hemisphere. Moreover, Russell and Voyer (2004) showed that the magnitude of the REA is similar in studies where an emotional component was present and in studies where it was not. Finally, it is worth noting that, according to Bryden (1978) and Cheatham and Herbig (1992), there is a generalized rightward orientational bias in right-handed people. As indicated in the Introduction, we predicted the processing of right-presented congruent beeps to benefit not only from the attraction of attentional resources to the spatial source of the emotional word (which would be the case also of left-presented congruent beeps), but also from the left-hemisphere activation associated with the recurrent processing of verbal material. The results of these three experiments confirmed this prediction. Moreover, only right-presented emotional words influenced significantly the spatial orienting of attention, and consequently the processing of the beep. Thus, the emotional valence of the words only has a systematic (in the case of taboo words) and reliable influence if it is presented at the side of the auditory space primed by left-hemisphere activation, hence locking the connections between the “what” and “where” systems only in the right side of the space. This seems to constitute a partial failure of evolutionary adaptation. It could indeed be so. Non-adaptive behaviours could in some circumstances result from the conjunction of two or more mechanisms that are, by themselves, adaptive. The adaptive value of hemisphere specialisation, particularly for language, is largely recognized (for recent reviews, see e.g., Hopkins, 2008; Josse & Tzourio-Mazoyer, 2004). This is also the case for the anatomical and functional decussation of the central nervous system relating, mostly in the vertebrates, each half of the brain to the opposite half of the body and of the environmental space, although its precise adaptive origin has been matter for debate for many years (see, e.g., Ramon y Cajal, 1898, and Suttie, 1926, vs. Braitenberg, 1965, for quite opposite views). The combination of two distinct adaptive mechanisms may not always be adaptive itself, such as when an auditory non-verbal stimulus is presented on the opposite side of a previous word (it being particularly relevant for some reason) which is processed in the left hemisphere and engages attention to the right of environmental space. Moreover, the asymmetrical pattern of attentional biases observed here could also depend on the specific experimental setting that we designed. If one considers sounds to be usually delivered by an object, and that they serve to attract visual attention towards this object, our experiments may have lacked ecological validity to some extent. A cross-modal setting, with an auditory emotional word followed by a visual target, could not lock the “what”–“where” connections exclusively to the right side and might then give rise to a fully adaptive attentional behaviour. Such experiments are currently in progress. In comparison to the unimodal setting used here, the cross-modal setting will offer a further advantage in allowing reducing the SOA (more precisely, the word-beep interval) without masking (through noise effects) the spoken words. This will allow better comparison with studies investigating attentional biases in the visual modality, since written words are generally briefly presented. In addition, observations would not be limited to a relatively late and limited snapshot of the influence of emotional stimuli on attentional orienting.

5.4. Non-spatial effects of emotional words In all experiments, taboo pairs led to longer RTs to the beep. These inhibitory effects of taboo words ought to be considered as nonspatial, because (a) they do not depend on the spatial congruence between the presentation sides of the emotional word and the beep and (b) they are observed even when no spatial dimension is involved (Experiment 2), namely when participants did not have to attend one side of space in order to repeat a word (as in Experiment 1) nor to localize the beep on each trial (as in Experiment 3). These effects can be related to the interference effects of taboo words observed in taboo Stroop tasks (e.g., MacKay & Ahmetzanov, 2005) and to their slowing effects in lexical decision tasks (Thomas & LaBar, 2005; but see MacKay et al., 2004), and interpreted as a freezing reaction, namely an inhibition of motor responses provoking a generic slowdown, similar to the interpretation of the interference and slowing effects of negative words (Algom, Chajut, & Lev, 2004). The fact that these non-spatial effects were also observed when there was a 250 ms delay between the offset of the words and the onset of the beep (long interval condition of the Experiment 1) supports this interpretation: indeed, Flykt (2006) suggested that if an effect of a threatening stimulus is still present after detection of this stimulus (namely during the withholding of the response), this effect can be located at the level of the response. Alternatively, some authors consider that general non-spatial effects of emotional words would actually reflect difficulties to disengage attention from their taskirrelevant emotional content (e.g., Estes & Verges, 2008; McKenna & Sharma, 2004) or the triggering of binding mechanisms which associate the source of an emotion (here, the word) with its context of occurrence (see MacKay et al., 2004 and MacKay et al., 2005). Further studies should aim at disentangling these interpretations and identifying the basis of the non-spatial effects we observed. For the time being, the fact that for taboo words general nonspatial effects were observed in both the short and the long interval conditions of Experiment 1 but attentional biases only in the short interval condition, indicates that these two effects are distinct and independent from each other. The general non-spatial effects are more long-lasting and less dependent on the immediate temporal succession of the emotional stimulus and the beep than the spatial attentional biases are, at least for taboo words. 5.5. Conclusion The present data are in agreement with the idea that the functional link between the “what” and the “where” auditory subsystems is reinforced by the emotional characteristics of the stimuli. The identification of a spoken emotional word automatically activates information about its spatial location, influencing the processing of a subsequent extraneous auditory stimulus. Nevertheless, only emotional words presented at the automatically primed side of the auditory space (in our case, the right side) affected the orienting of attention. This held true for taboo and, to a lesser extent, for negative words. This suggests that the “what”–“where” connections are locked exclusively to the right side of the space in a purely auditory situation using a linguistic material. Further work will aim to assess whether such a limitation disappears in audio-visual settings or with nonlinguistic emotional auditory materials. Acknowledgements This work was supported by two grants of the F.R.S.–FNRS (convention FRFC 2.4579.02 F and FNRS 1.5705.06). Many thanks to Marcha Van Boven for the help in preparing the material, to Olivia Gosseries and Ana Franco for testing the participants, as well as to Pascale Lidji and Chotiga Pattamadilok for their technical assistance.



Appendix A

Appendix A (continued) Emotional word French word

Words constituting the emotional pairs (included and excluded from the statistical analyses on the basis of the post hoc control studies), and their English translation. Emotional word French word

13

Neutral word English translation

Negative pairs Included in the statistical analyses Attaque Attack Bombe Bomb Bourreau Torturer Cadavre Corpse Cancer Cancer Carnage Slaughter Cercueil Coffin Chagrin Grief Colère Anger Coupable Culprit Crime Crime Danger Danger Echec Failure Haine Hate Hurler Scream Malheur Misfortune Massacre Massacre Menace Threat Menottes Handcuffs Meurtre Murder Misère Misery Morgue Morgue Mort Death Otage Hostage Panique Panic Peur Fear Prison Jail Ravage Devastation Sanglot Sob Seringue Syringe Sévices Abuse Sida Aids Souffrir Suffer Tank Tank Tombe Grave Torture Torture Tragique Tragic Violence Violence Excluded from the analyses Famine Starvation Hargne Aggressiveness Positive pairs Included in the statistical analyses Amour Love Beauté Beauty Bon Good Cadeau Gift Câlin Cuddle Chance Luck Charme Charm Confiance Trust Confort Comfort Content Glad Couple Couple Courage Courage Extase Ecstasy Fête Party Gentil Kind Guérir Recover Intime Intimate Joie Joy Merci Thanks Parfait Perfect Passion Passion Plage Beach Respect Respect

French word

English translation

Allure Bulle Baigner Convaincre Cadence Corniche Citrouille Charbon Quarante Quatorze Cloche Dessin Etoffe Hall Hardi Mélange Moutarde Minute Mésange Muscle Message Merle Mise Augure Pendule Poche Plateau Régate Sourcil Cerise Centime Semer Secteur Taupe Tâche Tartine Transit Voiture

Speed Bubble Bathe Convince Rhythm Cornice Pumpkin Coal Forty Fourteen Bell Drawing Cloth Hall Bold Blend Mustard Minute Chickadee Muscle Message Blackbird Putting Oracle Pendulum Pocket Tray Regatta Eyebrow Cherry Cent Sow District Mole Task Slice of bread Transit Car

Fissure Harpe

Crack Harp

Agence Bateau Bas Coton Caddie Chaise Chiffre Conduire Canard Carré Course Commune Estrade Phase Genou Garage Indice Juin Montrer Poster Panier Presse Rentrer

Agency Boat Low Cotton Trolley Chair Digit Drive Duck Square Race Town Platform Phase Knee Garage Clue June Show Post Basket Press Return (continued on next page)

Neutral word English translation

Positive pairs Included in the statistical analyses Rêve Dream Rire Laugh Romance Romance Sincère Sincere Sourire Smile Succès Success Tendre Tender Trésor Treasure Vacances Holiday Vie Life Excluded from the analyses Argent Money Désir Desire Gagnant Winner Gaieté Cheerfulness Partage Share Piscine Swimming pool Santé Health Taboo pairs Included in the statistical analyses Bander Have a hard-on Bite Dick Blondasse Dull blond Bonasse Hottie Bonniche Skivvy Bordel Brothel Catin Trollop Chiant Damn Clodo Bum Connasse Bitch Conne Twat Crapule Scoundrel Crétin Moron Débile Moronic Encule Bugger Foireux Yellow-bellied Foutre Cum Gerber Throw up Gueule Trap Ignare Ignorant Merde Shit Merdeux Squirt Morveux Jerk Nichon Tit Niquer Fuck Pédé Queer Pétasse Slut Péter Fart Pine Cock Pisser Pee Pouffiasse Tart Putain Whore Roulure Trollop Salope Bitch Tapette Queer Taré Cretin Taulard Con Traînée Slut Troncher Shag Excluded from the analyses Biroute Prick

French word

English translation

Robe Rôle Raquette Salade Seconde Sûrement Tourne Trafic Visite Va

Dress Role Racket Salad Second Surely Turn Traffic Visit Go

Aspect Décor Gazon Galop Parcours Pilote Salon

Appearance Decor Lawn Gallop Way Pilot Lounge

Bambou Bêche Brasseur Balise Banquise Bourgogne Coupon Chiot Cresson Canine Quinte Crevette Croquis Décade Amphore Foison Firme Jongler Gare Hippique Marque Matelot Merlan Napper Neiger Piquet Pudding Pommeau Pull Pigeon Pochoir Panneau Rameur Serrure Tisseur Tympan Teckel Trousseau Tréma

Bamboo Spade Brewer Beacon Ice field Burgundy Coupon Puppy Cress Canine Quintain Shrimp Sketch Decade Amphora Abundance Firm Juggle Station Horse Brand Sailor Whiting Coat Snow Peg Pudding Pommel Pullover Pigeon Stencil Panel Rower Lock Weaver Eardrum Dachshund Bunch Dieresis

Benzène

Benzene

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