Probing the link between cognitive control and lexical selection in monolingual speakers ∗
F.-Xavier Alario1 , Johannes C. Ziegler1 , Stéphanie Massol1,2 and Bruno de Cara3
1
3
Laboratoire de Psychologie Cognitive, Aix-Marseille Université and CNRS, France 2 BCBL - Basque Center of Cognition, Brain and Language, Spain Laboratoire de Psychologie Cognitive et Sociale, Université de Nice-Sophia Antipolis, France
ABSTRACT Whether bilinguals perform better than monolinguals in non-linguistic cognitive control tasks is a matter of current debate. Bilinguals are constantly required to switch and discriminate between their two languages. Such additional discrimination requirements are thought to result in improved domain-general cognitive control abilities compared to monolinguals. This rationale was examined by taking it one step further. A general link between general response selection (i.e., cognitive control mechanisms) and word selection should be apparent within the monolingual population, thus the natural variability present in response discrimination abilities should predict word selection in a population of monolinguals. A large group of young monolingual pupils were tested in the non-linguistic Simon task and in a picture naming word selection task. Selection difficulty was manipulated in both tasks. There were clear effects of response selection difficulty in either task, but there was no relationship between them at the individual level. This null effect provides no support for the hypothesis tested. It prompts a tentative discussion of exactly what process, in bilingual language use, may be capable of promoting cognitive control abilities.
∗ Corresponding author : Laboratoire de Psychologie Cognitive, CNRS & Université de Provence, Case D, 3 Place Victor Hugo, 13331 Marseille, France. Email:
[email protected] We thank L. Falicon and V. Boyeldieu for collecting the data, and the children and their parents for accepting to participate. This research has received funding from the European Research Council under the European Community’s Seventh Framework Program (FP7/2007-2013 Grant agreement 263575).
L’année psychologique/Topics in Cognitive Psychology, 2012, 112, 545-559
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F.-Xavier Alario
r Johannes C. Ziegler r Stéphanie Massol r Bruno de Cara
Un test du lien entre contrôle cognitif et sélection lexicale chez des locuteurs monolingues RÉSUMÉ La possible différence de performance entre les monolingues et les bilingues dans des tâches de contrôle cognitif est actuellement sujette à débat. Les bilingues doivent constamment alterner et discriminer entre leurs deux langues. Ce processus supplémentaire de discrimination, absent chez les monolingues, produirait une amélioration générale des habiletés de contrôle cognitif. Nous avons examiné une prédiction directement déduite de cette hypothèse générale. Si il y a effectivement un lien général entre processus génériques de sélection de réponse et sélection de mots, alors les variations naturellement présentes au sein d’une population monolingue des capacités de discrimination de réponse devraient être liées à la capacité à choisir des mots. Nous avons testé une large cohorte d’enfants monolingues dans la tâche non linguistique de Simon et dans une tâche de production de mots à partir de dessins. La difficulté de sélection a été manipulée dans chaque tâche. Nous avons observé de clairs effets de cette difficulté au sein de chaque tâche, mais pas de relation entre eux au niveau individuel. Cette absence d’effet significatif ne fournit pas d’arguments en faveur de l’hypothèse testée. Elle motive toutefois une discussion exploratoire des processus exacts qui, chez le locuteur bilingue, pourraient améliorer le contrôle cognitif.
Word selection for overt production is often described as a process in which linguistic information is retrieved from long term memory. Current models distinguish several types of information: grammatical (sometimes referred to as lemmas), phonological (sometimes referred to as lexemes), phonetic as well as articulatory programs (e.g., Levelt, Roelofs, & Meyer, 1999). Crucial for our purposes, this retrieval process involves a discrimination or selection stage in which the most appropriate word representation (lemma or lexeme, depending on the models) is singled out from among alternative candidates. Given these requirements, it is likely that abilities to discriminate among linguistic representations are grounded in general response selection abilities, such as those considered in cognitive control theories (e.g., Roelofs, 2003). This hypothesis finds support in observations made in the domain of bilingualism. The comparison of bilingual and monolingual speakers’ performance in cognitive and attentional control tasks has typically shown better performance for bilinguals than for monolinguals (Bialystok, 1999; Bialystok, Craik, Klein, & Viswanathan, 2004; Bialystok, Martin, & Viswanathan, 2005, Costa, Hernández, & Sebastián-Gallés, 2008; Lambert & Peal, 1962). This effect has been attributed to the fact that bilinguals are constantly required to discriminate among their two languages in their everyday word selections; for example, French-English bilinguals may need to choose the word “dog” while avoiding the equally meaningful word “chien”. The additional selection burden put on bilingual speakers,
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compared to monolinguals, would result in improved discrimination abilities. This improvement would be visible in non-linguistic tasks, above and beyond word discrimination (Bialystok, Luk, & Craik, 2008; Emmorey, Luk, Pyers, & Bialystok, 2008). This rationale is based on the assumption that there is a significant overlap between the processes at work for verbal response selection in speech and for arbitrary response selection in laboratory experiments (Abutalebi & Green, 2007; Bialystok, 2005; Green, 1998). These observations, however, have not remained uncontroversial. The so-called bilingual cognitive control advantage has not been observed in a number of carefully conducted studies, which compared bilinguals to monolinguals in non-linguistic tasks (Hilchey & Klein, 2011; Paap, Imai, Urtecho, Alcaine, & Keenan, 2011). For this reason, it appears desirable to probe explicitly the link between word selection and general response selection processes in other contexts. Such is the goal of the current study, where we tested the hypothesis described above by pushing its logic one step further, from the bilingual to the monolingual domain. If there is a close link between general response selection processes and word selection, this link should be apparent under multiple circumstances, even when the source of inter-individual variation is not driven by a single explicit cause such as bilingualism. For example, the (random) inter-individual variability in general response selection abilities should be associated with word selection abilities. In particular, such link should be apparent within each of the two groups that have been generally compared up to now. Here we considered monolinguals. To address this issue, we conducted an experiment in which a large number of self-declared monolinguals pupils (N > 80) were tested individually in four computer based tasks. The tasks all required response discrimination, on the basis of perceptual information, preponderant response inhibition, or verbal knowledge. The tasks were: a perceptual (hue) discrimination task, the classic Simon task, primed lexical decision and naming pictures in blocks (sometimes referred to as rapid automatized naming, or RAN, in developmental studies; Castel, Pech-Georgel, George, & Ziegler, 2008; Denckla & Rudel, 1976). They all included an “easy” and a “hard” condition (see Methods for details). The focus of our statistical analysis of the performance was the relationship between response discrimination abilities in each of the tasks across individuals (see also Davidson, Amso, Anderson, & Diamond, 2006). Of highest theoretical importance was the comparison of conflict resolution performance in the Simon task and in the picture naming task. In the former, a spatial information conflict is hypothesized to arise from
L’année psychologique/Topics in Cognitive Psychology, 2012, 112, 545-559
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F.-Xavier Alario
r Johannes C. Ziegler r Stéphanie Massol r Bruno de Cara
the requirement to inhibit irrelevant information (Kornblum, Hasbroucq, & Osman, 1990). In the latter, participants need to map the semantics extracted from the picture (i.e., object identity) with the corresponding verbal label (i.e., the picture name). A conflict is hypothesized to arise from the requirement to select the specific target word from among alternative semantically related words that are co-activated (Damian, Vigliocco, & Levelt, 2001). This experimental situation is taken here as a proxy for the increased difficulty in everyday word selection in bilinguals compared to monolinguals. The hue discrimination and lexical decision tasks did not have such strong theoretical motivation. They were included as a further test of the generality of conflict solving abilities across domains. To anticipate the results, there were clear effects of discrimination difficulty but these show little or no correlation between the tasks. While this is admittedly a null effect, this absence of a relationship stands in stark contrast with the predictions derived from the hypothesis of a significant overlap between abilities to discriminate among linguistic representations and general response selection abilities. The possible origins of this discrepancy suggest some avenues for future research.
EXPERIMENT Method Participants. A total of 88 children from grades 2 and 5 (in French terms, “Cours élémentaire 1” and “Cours Moyen 2”) were tested. Within each grade, the children attended school in 4 different classes. Further information about the participants can be found in Table 1. Three participants had to be excluded from the analysis because they did not participate in all the tasks, and two because they later reported speaking more than one language. This left a total of 83 pupils.
Table 1. Chronological and linguistic characteristics of the participants. Details on how reading and vocabulary ages were measured can be found under Stimuli and tasks in the text.
Age Grade
M
sd
Reading age range
M
sd
range
Vocabulary age M
sd
range
2nd grade 7; 10 5.6 7; 2 – 9; 2 7; 11 7.2 6; 9 – 9; 8 9; 4 22 4; 8 – 14; 0 5th grade 10; 10 6.9 10; 1 – 12; 4 10; 3 17.7 7; 9 – 13; 3 13; 10 48 7; 11 – 25; 9 M = mean. sd = standard deviation. Values in years; months or months.
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Stimuli and tasks. Evaluation pretests. The participants’ linguistic abilities were first pretested with two standardized tasks. These were administered during the first session with each child. Reading age was evaluated with the French test “Alouette” (Lefavrais, 1967), whose score is based on the number of words read, the number of errors, and the reading time using a standardized text. Vocabulary age was evaluated with a French version of the Peabody Picture Vocabulary Test Revised (Dunn, Theriault-Whalen, & Dunn, 1993). The test consists of 170 trials, in which the participant is given an auditory word and is asked to select the appropriate representation from among four alternative pictures. Hue discrimination task. Participants were presented with a display containing two squares colored in two shades of green, on a black background. They had to decide which of the two squares was darker. The darker and brighter squares were placed side by side randomly. Participants responded by pressing one of two keys (left or right) based on the position of the darker square. In the “easy” condition, the green shades were rather different (hue values 70 and 190 of a maximum of 255); in the “hard” condition they were considerably more similar (hue values of 100 and 140). There were 120 trials, distributed in 6 blocks (3 “easy” and 3 “hard”) of 20 trials each. This task is thought to tap primarily perceptual discrimination abilities. Simon task. We used a standard version of the Simon task (Simon, 1990). Participants were presented with a colored disk, either blue or orange, which was presented to the left or to the right of fixation. Participants had to respond with left and right button presses on the basis of the color of the disk while ignoring its location. In the “easy” condition, the color and the side were congruent (i.e. they cued the same response); in the “hard” condition the color and side were incongruent (i.e. they cued opposite responses). There were 100 trials distributed in 5 blocks of 20 trials each. Each block comprised 10 “easy” and 10 “hard” trials presented in a random order. This task is thought to tap the cognitive control ability to inhibit, or reject, a preponderant response (driven by the task-irrelevant presentation side). Picture naming task. Participants were required to name pictures depicting common objects (Alario & Ferrand, 1999; Snodgrass & Vanderwart, 1980). Each experimental trial contained one picture, and thus prompted a single word response. We selected a total of 25 pictures from 5 different semantic categories (fruits, furniture, musical instruments, tools, clothing items). Following a commonly used procedure, participants were first familiarized with the pictures to ensure they knew the depicted object and the corresponding name. The pictures were then presented in blocks comprising five different items, repeated 3 times in a random order (Denckla & Rudel, 1976). In the “easy” condition, the items within a block were semantically or otherwise unrelated; in the “hard” condition, the items within a block were drawn from a single semantic category (e.g. furniture). Lexical selection is known to be harder in the context of category co-ordinates, thus the performance in this task was taken as an index of lexical selection abilities (Damian et al., 2001). Lexical decision task. We used a standard masked priming lexical decision paradigm. In each trial, participants were presented with the following sequence
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F.-Xavier Alario
r Johannes C. Ziegler r Stéphanie Massol r Bruno de Cara
of events: a non-alphabetic pre-mask composed of five hash-marks (#####) for 480 milliseconds, a prime (80 ms), a non-alphabetic post-mask (32 ms), and finally the target (present until the participant’s response’). The prime and post-mask durations ensured that the prime was not consciously perceived by the participants1 . The prime was either a word or a pseudo-word, and so was the target. There were 44 target words selected from the children lexical database Manulex (Lété, Sprenger-Charolles, & Colé, 2004), and expected to be known by 2nd graders. Each of these target words was paired with two prime words, one of which was a neighboring word (differing only by one letter from the target) and the other unrelated. The prime words were selected from the same database, and were of higher lexical frequency (min = 50 occurrences per million, mean = 179, sd = 151) than the associated target (max = 20 occurrences per million, mean = 8.7, sd = 6.1). The prime and target words were matched on a variety of variables (see Table 2). Additionally, equal numbers of pseudo-words were created by changing one of the letters of the prime or target words. Four conditions were then created (prime word or pseudo-word; prime unrelated or orthographic neighbor) and associated with target word or pseudo-word. The task was to decide whether the target item was a word or a pseudo-word, by pressing one of two buttons. The focus was on yes (i.e. word) responses. In the “easy” condition, the prime was unrelated to the target; in the “hard” condition, the prime and target were orthographic neighbors, a relationship which is known to induced slower responses due to lexical competition (Grainger, O’Regan, Jacobs, & Segui, 1992).
Table 2. Matched characteristics of the items used in the lexical decision task.
Prime Property Frequency Nb Syllables Nb Letters Nb Phonemes Nb Graphemes Nb Orthographic neighbors Nb Phonological neighbors Nb Homophones Nb Homographs Bigram mean frequency Biphone mean frequency
Target
M
sd
M
sd
178.96 1.32 5.00 3.59 4.27 4.55 3.32 1.64 0.27 455 131
151.20 0.48 0.00 0.91 0.55 2.24 1.99 1.71 0.46 236 96
8.75 1.23 5.00 3.41 4.18 4.36 3.41 1.64 0.32 446 119
6.07 0.43 0.00 0.80 0.50 1.81 1.71 1.29 0.48 179 113
M = mean. sd = standard deviation.
1 No attempt was made to quantify the perceptual threshold for the prime words.
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Procedure. All the tests and tasks were administered individually at the back of the classroom. A total of five sessions, performed on five different days, were needed to test each participant. Each session lasted about 10 minutes. The pretest was always administered first, the four experimental tasks were administered in a counterbalanced order across participants. The pretests were paper-and-pencil tests. The four experimental tasks were given on a laptop computer using DmDX software (Forster & Forster, 2003). The instructions of the experimental tasks highlighted the requirement to go fast while avoiding errors.
Results Response times (RTs) were screened for errors, which were excluded from the RT analysis. Latencies and error rates were analyzed in separate but similarly structured analyses. We computed standard ANOVAs with participants as random factors within each task; for the linguistic tasks (picture naming and lexical decision) we also report ANOVAs with items as random factors (i.e., F1 and F2 analyses). We tested the effect of response discrimination difficulty (easy vs. hard), the effect of grade, and their interaction. The data are summarized in Table 3. Table 3. Summary of average performance across conditions in the four experimental tasks.
Tasks Grade
Conditions
2nd grade
easy hard easy hard
5th grade
Perceptual M 721 745 584 604
sd 101 116 84 96
Simon Err 11.9 15.2 5.9 8.6
Naming 2nd grade 5th grade
easy hard easy hard
M 786 812 684 722
sd 69 82 68 73
M 733 739 573 587
sd 97 97 91 88
Err 11.5 11.0 6.8 8.4
Lexical decision Err 17.6 20.6 6.8 8.2
M 1442 1451 1046 1050
sd 309 366 205 192
Err 25.1 25.5 16.9 17.1
M = mean (in ms); sd = standard deviation: Err = error rate (in %)
L’année psychologique/Topics in Cognitive Psychology, 2012, 112, 545-559
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F.-Xavier Alario
r Johannes C. Ziegler r Stéphanie Massol r Bruno de Cara
In the hue discrimination task, participants were faster in the easy than in the hard condition (F[1-83]=7.51, p
