Dissociated developmental trajectories for semantic and phonological ...

MEMORY, 2006, 14 (5), 624 636

Dissociated developmental trajectories for semantic and phonological false memories Robyn E. Holliday University of Kent at Canterbury, UK Brendan S. Weekes University of Sussex, Brighton, UK False recognition following presentation of semantically related and phonologically related word lists was evaluated in 8-, 11-, and 13-year-olds. Children heard lists of words that were either semantic (e.g., bed, rest, wake . . .) or phonological associates (e.g., pole, bowl, hole . . .) of a critical unpresented word (e.g., sleep, roll), respectively. A semantic false memory was defined as false recognition of a semantically related but unpresented word. A phonological false memory was defined as false recognition of a phonologically related but unpresented word. False memories in the two tasks showed opposite developmental trends, increasing with age for semantic relatedness and decreasing with age for phonological relatedness.

False memories have been studied extensively in the adult literature using the Deese/Roediger/ McDermott (DRM) paradigm (Deese, 1959; Roediger & McDermott, 1995) primarily because high levels of false recall and false recognition can be induced under controlled conditions. There has also been intense interest in the DRM paradigm among developmental researchers, because manipulations and resulting dissociation patterns can evaluate two prominent accounts of false memories, activation-monitoring theory (AMT) (e.g., McDermott & Watson, 2001; Roediger & McDermott, 2000) and fuzzy-trace theory (FTT) (e.g., Brainerd & Reyna, 1998, 2001). These theories make opposite predictions about the developmental trajectory of false memories in this paradigm *AMF predicts age decreases and FTT predicts age increases. Extant data favour the latter age trend (e.g., Brainerd, Forrest, & Karibian, in press; Brainerd, Reyna, & Forrest, 2002; Howe, Cicchetti, Toth, & Cerrito,

2004; Metzger, Warren, Price, Reed, Shelton, & Williams, 2004; but see Ghetti, Qin, & Goodman, 2002). In this paper, we report true and false memories in children aged 8 to 13 years on two recognition tasks: a typical semantic DRM task and a phonological DRM task (cf. Westbury, Buchanan, & Brown, 2002). In the typical DRM task, participants study lists of words that are all semantic associates of a critical lure (unpresented word). For example, nurse, sick, lawyer, medicine, health , hospital , dentist , physician , ill , patient , office, stethoscope are all related in terms of meaning to the critical lure doctor. Brainerd et al. (in press; 2002) and Howe et al. (2004) reported that false recognition and false recall increased from 56 years to 1112 years. Similarly, Price et al. (2001) and Warren et al. (2003) reported age-related increases in false recall and false recognition from 7 years to young adulthood. Dewhurst and Robinson (2004) replicated this pattern for false recall

Address correspondence to: Robyn E. Holliday, Department of Psychology, University of Kent at Canterbury, Canterbury, CT2 7NP, UK. E-mail: [email protected] Portions of this work were presented at 44th Annual Meeting of the Psychonomic Society, Vancouver, Canada, 2003.

# 2006 Psychology Press Ltd http://www.psypress.com/memory

DOI:10.1080/09658210600736525

SEMANTIC AND PHONOLOGICAL FALSE MEMORIES

in 5- to 11-year-olds. Metzger et al. (2004) reported a similar age trend when they used word lists generated by the children themselves. In this paper we refer to this task as the semantic DRM task. Phonological false memories have also been investigated but only in young adults (e.g., Chan McDermott, Watson, & Gallo, 2005; McDermott & Watson, 2001; Sommers & Lewis, 1999; Wallace, Stewart, & Malone, 1995; Wallace, Stewart, Shaffer, & Wilson, 1998; Watson, Balota, & Roediger, 2003; Westbury et al., 2002), the elderly and patients with dementia (e.g., Budson, Sullivan, Daffner, & Schacter, 2003; Sommers & Huff, 2003). Sommers and Lewis (1999) examined phonological false recognition in young adults by presenting spoken word lists that varied in the sublexical relations between study and test items specifically at the level of the rime (i.e., the final two phonemes). They found similar levels of false recognition in semantic and phonological DRM tasks and argued that this was evidence of the operation of automatic activation of critical lure words. Westbury et al. (2002) also investigated false phonological recollection using the DRM task in order to test predictions derived from the cohort model of spoken word recognition (Marslen-Wilson & Tyler, 1980) The cohort model assumes that during early auditory processing of a word, a cohort of word candidates that is consistent with incoming sensory information is triggered. Candidate words are successively eliminated from the cohort as each new phoneme in the word is processed. Word recognition thus occurs sublexically when the cohort is reduced to a single word. Westbury et al. (2002) reasoned that phonological false recollection may differ according to the sublexical relations between the study and list words, and compared sublexical relations at the level of the initial phoneme, the head (first two phonemes), and the rime (final two phonemes) using written lists that varied the position of phonological overlap (i.e., initial phoneme, head, rime) between studied words and critical lures. They reported greater phonological false recognition for head relations than initial phoneme and rime relations, and equivalent levels of false recognition for the head and rime relations, thus supporting the cohort model. In this paper, we refer to this task as the phonological DRM task No study has investigated sublexical false memory phenomena in children using spoken

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words. Nor, to the best of our knowledge, has any study directly compared in children DRM lists consisting of phonologically and semantically related words. One study compared phonological and semantic false recollection in children posthoc using free recall memory tests.1 Dewhurst and Robinson (2004) presented 57 children aged 5 to 11 years with five semantically related DRM lists. Each list contained 8 of the 15 DRM words for that list. The words were selected because each had one or more rimes associated with it (e.g., nap cap ). Dewhurst and Robinson reported that rime errors predominated in the 5- and 8-yearolds, but more semantic errors were made by the 11-year-olds than the 5-year-olds. Dewhurst and Robinson posited that this dissociation was due to a developmental shift from phonological to semantic processing with age. Note, however, that the children did not study lists of phonologically related words.

THEORETICAL ISSUES AND PREDICTIONS Activation-monitoring theory (AMT) was developed to explain false memories in the semantic DRM paradigm (McDermott & Watson, 2001; Roediger & McDermott, 2000). In essence, AMT combines two theoretical accounts of memory, namely (spreading) activation (e.g., Anderson & Pirolli, 1984; Collins & Loftus, 1975) and memory source monitoring (e.g., Johnson, Hashtroudi, & Lindsay, 1993). Presentation of meaning associates on a DRM study list activates a network of connecting nodes. For example, studying bed, rest , awake . . . activates the critical lure for this list, sleep. At test, a participant must decide (or monitor) whether or not a test word was part of the study list. AMT predicts that high levels of activation should produce high levels of false recognition due to the very strong meaning associations between study words and the critical lure. Likewise, memory source monitoring predicts high levels of false recognition for the same reason. Concerning developmental effects, AMT predicts that false recognition (of critical lures) in DRM tasks will decrease due to age improvements in correct source attributions 1

While we were preparing the research presented in this paper for publication we became aware of Dewhurst and Robinson’s (2004) work. Our research was not specifically designed to test their findings.

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(e.g., Ackil & Zaragoza, 1995; Drummey & Newcombe, 2002; Lindsay, Johnson & Kwon, 1991). Fuzzy-trace theory (FTT) holds that participants store and retrieve two distinct memory traces of an experience, verbatim traces and gist traces (Brainerd & Reyna, 1998). Verbatim traces are ‘‘integrated representations of a target’s surface content and other item-specific information’’ (Brainerd & Reyna, 2005, p. 84) whereas gist traces are ‘‘episodic interpretations of concepts (meanings, relations, patterns) that subjects access, or elaborations that they generate, as they encode targets’ surface form’’ (Brainerd & Reyna, 2005, p. 85). In this paper, we define ‘‘semantic’’ gist as the general thematic relation of a list of words (e.g., bed, rest , awake . . .) whose meanings converge on an unpresented but highly semantically related critical lure theme (e.g., sleep ). We define ‘‘phonological’’ gist as the general thematic relation of a list of words (e.g., coal , pole, soul . . .) whose phonological relations at the sublexical level converge on a unpresented but highly phonologically related critical lure theme (e.g., roll ). The current research aimed to test predictions that fall out of two of FTT’s core principles* opposing judgements about false memory items, and developmental variability (Brainerd, 2005; Brainerd & Reyna, 2005). FTT posits that information about an event is stored in dissociated memory traces *verbatim the actual surface form (e.g., ‘‘drank a Pepsi’’); and gist the list’s theme, meaning, patterns (e.g., ‘‘drank a soft drink’’). Verbatim traces contain vivid details of a word’s prior presentation. Gist traces contain details that are consistent with the theme of the studied list (Brainerd & Reyna, 2005). Retrieval of gist traces supports recall and recognition of false yet thematically consistent events (e.g., ‘‘drank a Sprite’’). For true recognition, verbatim and gist retrieval processes work together. For false recognition, however, verbatim and gist retrieval processes oppose each other. Gist retrieval supports false recognition of thematically related but unpresented critical lures. Verbatim retrieval suppresses false recognition via a mechanism known as recollection-rejection ; that is, the ability to use vivid verbatim representations of a word’s prior presentation to reject false details (e.g., ‘‘I could not have drunk a Sprite because I remember drinking a Pepsi’’) (Brainerd, Reyna, Wright, & Mojardin, 2003).

Turning now to the principle of developmental variability, FTT predicts that false memories in the semantic and phonological DRM tasks may differ across age. The predicted trajectory in the semantic task is that false memories will increase with age. FTT’s explanation is that the ability to connect the gist (Reyna & Lloyd, 1997) across a list of semantically related words improves with age (independent of improvements in vocabulary) (Reyna, Mills, Estrada, & Brainerd, in press). We know from research in memory-strategies development that young children do not spontaneously organise meaning-related words in categories (e.g., the sleep category would contain the words bed , rest , awake. ..) but will do so by early adolescence (Bjorklund & Jacobs, 1985; Bjorklund, Schneider, Cassel, & Ashley, 1994). At the same time, the ability to use vivid verbatim traces to suppress false but gist-consistent words increases with age (Brainerd, 2005; Brainerd et al., 2003). As noted earlier, the bulk of empirical studies report that the developmental trajectory of false memories in the typical (semantic) DRM task is one of increased susceptibility from early childhood to adolescence as well as age-related increases in verbatim recollection (e.g., Brainerd et al., in press, 2002; Howe et al., 2004; Warren, Reed, Mangan, & Metzger, 2003). By contrast, the predicted trajectory in the phonological task is that false memories will decrease with age. The reasoning for this prediction rests on two assumptions. First, phonological gist traces will not increase with age because the number of sounds in a language is finite; unlike the number of meanings in a language, which is infinite. English has 49 phonemes, which in combination make up over 50,000 words (Kucera & Francis, 1967). Most children acquire the basic sounds of their language from a relatively young age and then learn to parse and combine these sounds in order to learn new word forms (Jusczyk, 1999). Second, given a finite number of sounds there is considerable pressure in the developing lexicon to parse new phonological forms at the sublexical level of the initial phoneme, the head, and the rime, since similarsounding words have very different meanings (e.g., sleet and sleepMetsala & Walley, 1998). The consequence of these psycholinguistic constraints is first that there should be evidence of phonological false recollection at the sublexical level in young children (as reported in Westbury et al., 2002), and crucially that verbatim


traces will have the opportunity to oppose phonological gist traces more readily than in the semantic task (Brainerd et al., 2003). In a spoken word task, this verbatim suppression is expected to be strongest in the head condition since that is the primary level of sublexical activation required to recognise a word according to the cohort Model (Marslen-Wilson, 1990). It follows that the strength of the phonological false memory and its developmental trajectory will depend on the locus of the phonological overlap between studied and unpresented words. In English words, where initial processing is most heavily concentrated in the initial phonemes (Wallace et al., 1998), verbatim suppression difficulties should be more serious when phonological overlap occurs at the beginning rather than end of words. Furthermore, for equivalent amounts of phonological overlap, the strength of the phonological false memory effect and its predicted developmental trajectory is predicted to be more marked for earlier than for later overlap. Hence, head relations (initial phoneme and first vowel: leave, lead, league) should produce stronger false memories in children and a more pronounced age decline than rime relations (last vowel and last phoneme: make, sake, awake). Thus, FTT predicts different developmental trajectories in false memories across semantic and phonological DRM tasks according to age. There is no extant evidence to support this prediction using a phonological DRM task. However, research by Brainerd and colleagues has reported that false memories for rime and for nonsense words decrease with age (Brainerd, Reyna, & Brandse, 1995; Brainerd, Reyna, & Kneer, 1995; Brainerd, Stein, & Reyna, 1998). Dewhurst and Robinson (2004) and others (e.g., Bach & Underwood, 1970) suggest that the phonological gist (i.e., the thematic relation) of a particular list (e.g., gail , tail , shale, bail , nail all rime with the critical lure, rail ) are more easily encoded and stored at younger ages in comparison to meaning-related gist. To clarify, in order to learn a specific word’s meaning, one must be able to distinguish between words at the sub-lexical level of individual phonemes.

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THE PRESENT RESEARCH To test our hypotheses we administered both semantic DRM lists (cf. Stadler, Roediger, & McDermott, 1999) and phonological DRM lists (cf. Westbury et al., 2002) to three groups of children aged between 8 and 13 years. In the semantic DRM task, children studied words that are meaning associates of a critical lure. In the phonological task, children studied lists of words that are phonological associates of a critical lure. Some lists involved head relations (i.e., the first two phonemes) and some involved rime relations (i.e., the final two phonemes). Some additional lists were also administered in which words shared only the initial phoneme (e.g., wail, wing, ¯ ¯they wan). Recognition tests were chosen because ¯ are typically more sensitive than recall tests to age changes in false memories in the semantic DRM paradigm, and because studies report that false recall in young children with this method sometimes approaches floor levels (see Brainerd et al., 2002). The two types of false responses (semantic and phonological) were factorially crossed with two types of encoding relations (semantic versus phonological).

METHOD Participants The participants were 52 8-year-olds (M /8.94 years), 52 11-year-olds (M /10.99 years), and 52 13-year-olds (M /12.99 years) who attended schools in predominantly white, middle-class areas. All were native speakers of English with no reported history of speech or hearing difficulties.

Materials In the semantic DRM task, the first 10 words from nine Stadler et al. (1999) lists that appear in the top half of the ranking of false recognition of a critical lure served as list words in the presentation phase. The remaining 27 Stadler et al. lists were the source of unrelated distractors and practice items for the recognition tests. Each recognition test consisted of five list words

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(targets) originally presented in the first, third, fifth, seventh, and ninth positions of each list, the critical lure for each list, two related distractors for each list (eleventh & twelfth words), and two unrelated (unpresented) distractors. The nine lists of 10 words developed by Westbury et al. (2002), Experiment 1) provided the list words and distractor materials for the phonological DRM task.2 Three lists were related in the initial phoneme position, three related in the head position, and three related in the rime position. Each recognition test consisted of five list words (targets) originally presented in the first, third, fifth, seventh, and ninth positions of each list (three phonologically related, two phonologically unrelated), the critical lure for each list, two related distractors, and two unrelated distractors (sharing no phonemes with the critical lure). Test lists were ordered such that an equal number of each word type was presented in the first and second half of each list. The critical lure for each list was positioned in the middle triplet of the list (i.e., between fourth and seventh positions). Auditory discrimination was assessed using the Auditory Discrimination and Blending Test from the Supplementary Diagnostic Tests of the NARA-11 (Neale, 2000). This was necessary in order to ensure that no children had a disorder in spoken language processing. All children achieved age-appropriate scores on this test.

Procedure Children were randomly assigned to either the semantic or the phonological condition and tested individually in a quiet room at their school. Instructions were given that they would be asked to remember list words after hearing a list. An audiotape of the first list of 10 words was presented in the usual order (semantic condition: strongest-to-weakest associates of the critical lure; phonological condition: order cf. Westbury et al., 2002) at a rate of one every 3 seconds followed by a 1-minute distractor task (i.e., number shadow2 Westbury et al.’s (2002) lists were constructed using computer-aided dictionary searches. Word frequency effects, sub-lexical frequency effects, orthographic and phonological neighbourhood sizes were also considered. Westbury et al. noted that because control of all these variables was impractical, studied words were randomised across the variables. Word lists are available from the first author.

ing). Next, practice lists and practice tests were administered to assess understanding of test instructions. Each child listened to an audiotape of 1 of the 27 unpresented DRM lists (car or black list) in the semantic condition, and 1 of 2 unpresented Westbury et al. (2002) lists (seal , or bake, positions head & rime, respectively) in the phonological condition. The experimenter then read the first practice list words at 3-second intervals, followed by the test list words at 3second intervals. Prior to this practice test, children were asked to say ‘‘yes’’ to words they had heard the experimenter read and ‘‘no’’ to all the other words. Children who answered correctly on this test proceeded to the main test phase; if not, the second practice test was given. Only children who answered correctly on the second practice test proceeded to the main test phase.3 After the first recognition test for the first presented list, children received eight more cycles of one semantic DRM list or one phonological DRM list, followed by a 1-minute distractor task, followed by a practice test, followed by a recognition test.

RESULTS Semantic DRM task The mean proportions of ‘‘yes’’ responses to targets (list words), critical lures, semantically related distractors, and unrelated distractors (new words) are presented in Table 1. Corrected proportions for targets, critical lures, and related distractors were converted to A? (Snodgrass & Corwin, 1988) (corrected proportions of unrelated distractors were the false alarms in these calculations; Snodgrass & Corwin, 1988).4 We 3 More than 96% of the children in each age group answered correctly on the first semantic and phonological practice tests. Practice lists comprised only list (targets) words and unrelated words; no critical lures were presented in practice tests. 4 Individual proportions of yes responses for these items were corrected using Snodgrass and Corwin’s (1988) procedure to eliminate mean yes responses of 1 or 0 (cf. Holliday, 2003; Holliday & Hayes, 2000; Seamon, Luo, Schwartz, Lee, & Jones, 2000). In this procedure 0.5 is added to the number of yes responses, which are then divided by N/ 1, where N in this context refers to the total number of test items for targets, critical distractors, semantically related distractors, and unrelated distractors. The corrected proportions in all conditions were essentially the same as the raw proportions. Hence, on the advice of a reviewer we have omitted these from the manuscript.

SEMANTIC AND PHONOLOGICAL FALSE MEMORIES TABLE 1 Mean proportions (yes responses) of targets and critical lures, related and unrelated distractors by age and experimental conditions 8-year-olds 11-year-olds 13-year-olds Semantic condition Item type Target Critical lure Related distractor Unrelated distractor

.77 .54 .15 .06

(.11) (.26) (.15) (.08)

Phonological condition Item type Initial phoneme position Related target .71 (.13) Unrelated target .71 (.15) Critical lure .41 (.32) Related distractor .34 (.30) Unrelated distractor .30 (.26) Head position Related target .73 (.11) Unrelated target .61 (.23) Critical lure .63 (.20) Related distractor .45 (.25) Unrelated distractor .15 (.14) Rime position Related target .68 (.16) Unrelated target .63 (.21) Critical lure .38 (.34) Related distractor .31 (.26) Unrelated distractor .24 (.22)

.81 .65 .11 .02

(.09) (.23) (.10) (.04)

.83 .82 .18 .03

(.08) (.14) (.09) (.05)

.75 .72 .31 .22 .10

(.19) (.20) (.23) (.17) (.15)

.79 .76 .31 .24 .17

(.15) (.13) (.27) (.20) (.15)

.75 .71 .38 .39 .06

(.18) (.19) (.26) (.27) (.12)

.73 .76 .32 .46 .12

(.18) (.15) (.22) (.22) (.13)

.71 .69 .22 .27 .24

(.16) (.18) (.25) (.18) (.19)

.77 .72 .18 .25 .20

(.15) (.18) (.22) (.20) (.13)

Standard deviations in parentheses.

also calculated a measure of response bias asso? (cf. Donaldson, 1992). B?D ? ciated with A ?, B ?D values vary from /1 (extremely liberal) to 0 (no ? bias) to /1 (extremely conservative). A? and B?D values for targets, critical lures, and related distractors are presented in Table 2. The significance level for all Tukey HSD pair-wise comparisons was set at p B/.05. (See Appendix for all formulae.) A 3 (age) /3 (word type: target, critical lure, related distractor) ANOVA with repeated measures was performed on the A? data. There were main effects for age, F (2, 75) /15.92, MSE /.08, p B/.001, h2p /.298, and for word type, F (2, 150) / 423.58, MSE /.04, p B/ .001, h2p /.850, which were qualified by an Age /Word Type interaction, F (4, 150) / 4.04, MSE / .04, p B/ .01, h2p /.097. Pair-wise comparisons revealed that across age groups, true recognition of targets (M /.93) was higher than false recognition of critical lures (M /.88) and related distractors (M /.66). Three interesting developmental

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findings emerged. First, true recognition of targets increased between 8 years (M /.91) and 11 years (M /.93) but not between 11 years and 13 years (M /.94). Second, false recognition of critical lures increased from 8 years (M /.83) to 11 years (M /.88) to 13 years (M /.93). Third, false recognition of related distractors (the eleventh list word) increased from 11 years (M /.65) to 13 years (M /.72) but not between 8 years (M /.60) and 11 years (M /.65) (see Figure 1). ƒ for targets, critical lures, Next, measures of BD and related distractors were entered into a 3 (age) /3 (word type: target, critical lure, related distractor) ANOVA with repeated measures on the last factor. There was a main effect for word type, F (2, 150) /57.18, MSE /.05, h2p /.433; across age, children adopted a more conservative response bias for related distractors (M /.96) than for critical lures (M /.66) and targets (M /.58).

Phonological DRM task The mean proportions of ‘‘yes’’ responses to related and unrelated targets, critical lures, related distractors, and unrelated distractors for each onset position are presented in Table 1. As for the semantic DRM analysis, corrected proportions of yes responses to related and unrelated targets, critical lures, and related distractors were converted to A? (Snodgrass & Corwin, 1988) (corrected proportions of unrelated distractors were the false alarms in these calculations) and ƒ are presented in Table 2. the bias measure BD The significance level for all Tukey HSD pair-wise comparisons was p B/.05. A 3 (age) /3 (onset position: initial phoneme, head, rime) /4 (word type: related target, unrelated target, critical lure, related distractor) mixed ANOVA with repeated measures on the last two factors was performed on the A? data. Main effects were found for (1) onset position, F (2, 150) /29.65, MSE /.03, p B/.001, h2p /.283; yes responses were greatest in the head position: rime (M / .66) B/initial phoneme (M /.69) B/ head (M /.76); (2) word type, F (3, 225) / 157.88, MSE /.02, p B/.001, h2p /.678.Yes responses were greater for related (M /.82) and unrelated targets (M /.80) than for critical lures (M /.59) and related distractors (M /.60). The Onset Position /Word Type interaction was also significant, F(6, 450) /7.34, MSE /.01, p B/.001,

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TABLE 2 Mean memory sensitivity (A? )(yes responses) for targets and critical lures, related and unrelated distractors by age and experimental conditions 8-year-olds Semantic task Item type Target .91 (.53) Critical lure .83 (.70) Related distractor .60 (.93) Phonological task Item type Initial phoneme position Related target .75 (.02) Unrelated target .74 (.03) Critical lure .63 (.38) Related distractor .51 (.44) Head position Related target .83 (.26) Unrelated target .77 (.41) Critical lure .74 (.41) Related distractor .69 (.58) Rime position Related target .77 (.14) Unrelated target .79 (.24) Critical lure .60 (.52) Related distractor .56 (.57)

11-year-olds

13-year-olds

.93 (.65) .88 (.74) .65 (.98)

.94 (.57) .93 (.55) .72 (.97)

.85 .84 .56 .60

(.29) (.34) (.77) (.83)

.85 .84 .58 .55

(.078) (.17) (.70) (.77)

.87 .86 .61 .73

(.41) (.50) (.76) (.75)

.84 .86 .59 .72

(.28) (.28) (.74) (.66)

.79 .76 .51 .52

(.08) (.15) (.64) (.64)

.82 .80 .52 .52

(.01) (.14) (.73) (.74)

B?? in parentheses.

h2p /.089. Pair-wise comparisons confirmed that children were more likely to respond yes to related targets and unrelated targets in the initial phoneme and head positions than in the rime position. Children were also more likely to respond yes to critical lures (M /.65) and related distractors (M / .72) in the head position than in the initial phoneme (M /.59) and rime positions (M /.54). Turning now to developmental findings, a significant interaction for Age /Word Type was

found, F (6, 225) /6.99, MSE /.02, p B/.001, h2p / .157. Pair-wise comparisons revealed developmental increases from 8 to 11 years in yes responses to related targets (M8-years /.78, M11years /.84, M13-years /.84) and to unrelated targets (M8-years /.74, M11-years /.82, M13-years /.83). Developmental decreases from 8 years (M /.66) to 11 years (M /.56) and 13 years (M /.56) in yes responses to critical lures was also found, which is in the opposite direction to the effects found in the semantic task (see Figure 2). ƒ bias measures for related and unNext, BD related targets, critical lures and related distractors were entered into a 3 (age) /3 (onset position: initial phoneme, head, rime) /4 (word type: related target, unrelated target, critical lure, related distractor) ANOVA with repeated measures on the last two factors. Main effects were found for (1) word type, F (3, 225) /7.33, MSE / .15, h2p /.089, and (2) position, F(2, 150) /5.54, MSE /.07, h2p /.069; and interaction effects for Word Type /Position, F (6, 450) /72.92, MSE / .10, h2p /.493, and Word Type /Position /Age, F (12, 450) /3.37, MSE /.10, h2p /.083. Pair-wise comparisons on the three-way interaction revealed that for all word types in the initial phoneme position, the 8-year-olds adopted a more liberal response bias than the older two groups, but in the head position and in the rime position this trend was only found for critical lures.

DISCUSSION Our most significant finding was the dissociation between the developmental trajectories of semantic and phonological false recognition.

1 .94 .93

.93

.91

88

0.9 .83 0.8

.72 0.7 0.6

.65

Targets Critical lures

.60

Related distractors

0.5 0.4 8-years

11-years

13-years

Figure 1. Semantic DRM task: Mean A? proportions of yes responses as a function of word type and age.


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1 0.9 0.8 0.7

.84 .82

.84 .83

.78 .74

Related targets Unrelated targets

.66 .62 .59

0.6

.60 .56

.56

Critical lures Related distractors

0.5 0.4 8-years

Figure 2.

11-years

13-years

Phonological DRM task: A? mean proportions of yes responses as a function of word type and age.

Specifically, as predicted, false alarms to critical lures increased with age when children studied semantic DRM lists and decreased with age when they studied phonological DRM lists. True recognition of targets also increased with age in both semantic and phonological tasks. Our semantic DRM results are compatible with prior developmental studies, which have reported that children falsely recognise critical lures that are associated in meaning to studied list words (Brainerd et al., in press, 2002; Dewhurst & Robinson, 2004; Howe et al., 2004; Metzger et al., 2004). Indeed, by age 13 years, true recognition of targets and false recognition of critical lures attained levels similar to those reported in the adult DRM literature (e.g., Roediger & McDermott, 1995). False recognition of related distractors (the weakest semantic associate, eleventh list word) increased with age in the two older groups only. There is only one published study whose results run counter to the typical pattern of age-related increases in reporting of critical lures in the semantic DRM task. Ghetti et al. (2002) found a developmental decrease in false recall of critical lures from 5 to 7 years. Note, however, that Ghetti et al.’s methods differed from the aforementioned developmental studies and our own. Ghetti et al.’s DRM word lists were shorter (i.e., 7 words instead of 10 15), and half the lists were presented as pictures instead of words. Short study lists and pictures are known to reduce adults’ false memories in this paradigm (e.g., Israel & Schacter, 1997; Robinson & Roediger, 1997) probably because such manipulations encourage verbatim rather than gist processing (Brainerd et al., 2002). Also note that Ghetti et al.’s

recognition results could have been influenced by prior recall tests. 5 We also found, as predicted, that the phonological false memory effect was greater when list and test words overlapped in the head position (i.e., initial phoneme/first vowel) than in the initial phoneme and rime positions, although it should be stressed that false memories were also found for words that shared initial phoneme and rime onset positions. A similar pattern has been reported in adult phonological false recollection (Sommers & Lewis, 1999; Westbury et al., 2002). Such findings are compatible with the cohort model of auditory word recognition (e.g., Marslen-Wilson, 1990). For both true and false recognition, the effects were larger when the list and test words shared phonology in the head onset position. These latter effects held throughout the age span tested. The dissociated developmental trajectories of phonological and semantic false memories can be explained by FTT. Specifically, FTT proposes that false recognition of critical lures in a semantic DRM task will increase with age between early 5

In the semantic DRM paradigm in which list words repeatedly cue the same meanings, false recognition of a critical lure for a particular list can sometimes be accepted on the basis of two processes * phantom ‘‘remember’’ recollection (i.e., illusory conscious recollection of the prior ‘‘presentation’’ in the list of a critical lure; Brainerd et al., 2003) and familiarity (i.e., on the basis of meaning content; Brainerd, Wright, Reyna, & Mojardin, 2001). Precise estimates of the contributions of phantom recollection, familiarity, and recollection to recognition (while controlling for response bias) are obtained using the conjoint-recognition model (e.g., Brainerd et al., 2001). It should be noted that the Remember/Know task (cf. Gardiner & Java, 1991) is beyond the capabilities of children of the age range tested here. Indeed, we are not aware of any empirical studies using this task with children.

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childhood and early adolescence, because these responses depend on the ability to store and retrieve gist memories that connect meaning across thematically related words (Brainerd & Reyna, 1998, 2005). Verbatim retrieval of a list word, on the other hand, facilitates rejection of a phonologically related lure (e.g., retrieve cat reject mat as not presented) or a semantically related critical lure (e.g., retrieve bed reject sleep ) (Brainerd et al., 2003). Developmental improvements in recollection rejection (i.e., the ability to use vivid verbatim traces) allow better rejection of false details. These are unopposed by phonological thematic relations (which are finite) but continue to be opposed by age-related increases in meaning-based gist (which is infinite). Hence, the principle of opposing processes favours age improvements in phonological memory but a trade-off for semantic false memories due to increased access to meaning-based gist and verbatim traces. Note, however, that phonologically related lures might be better cues for verbatim representations via encoding specificity (e.g., Tulving &Thomson, 1973) because the retrieved and stored words match (they share surface features with presented items). What are the implications of a developmental dissociation between semantic and phonological false recognition for an AMT account of false memories (e.g., McDermott & Watson, 2001; Roediger & McDermott, 2000)? Currently, a (spreading) activation model (e.g., Anderson & Pirolli, 1984; Collins & Loftus, 1975) does not specify any distinction between semantic and phonological features. Our finding that phonological false memories decrease with age was premised on the view that phonological and semantic lexicons are modular. For speakers of English, the size of the phonological lexicon is constrained by the number of phonemes whereas the semantic lexicon continues to grow as the lexicon expands. In order to begin processing the meaning of a word, children must first identify the relevant phoneme for that word, and inhibit subsequent phonemes according to the cohort model (e.g., Marslen-Wilson, 1990). Phoneme discrimination is also necessary to learning the meaning of a word. However, activation of similar-sounding words specifically at the level of the head becomes redundant as the lexicon grows, possibly resulting in pressure to inhibit phonological gist. There is no reason on the basis of AMF alone to posit that meaning relations but not phonological relations would be activated as

the lexicon develops, because AMT assumes coactivation at the level of sound and meaning (e.g., Chan et al., 2005).6 Also, development should improve source monitoring in general (e.g., Ackil & Zaragoza, 1995; Drummey & Newcombe, 2002; Lindsay et al., 1991; for a review see Roberts & Blades, 2000) so that developmental trends for semantic and phonological associates ought to be equivalent or, at the very least, that improved source monitoring should improve performance for both semantic and phonological associates. Our results are therefore quite difficult to explain using a straightforward application of the source-monitoring framework. In our view, the crucial difference in explanatory power between FTT and AMT is that the latter lacks opposing processes that can account for dissociable trends across age. That is, improvements in source monitoring should affect rejection of both phonologically and semantically similar words, and certainly should not send them in opposite directions developmentally. The pattern of effects for children’s true and false phonological recognition reported here is problematic for this view. However, they clearly lend support to FTT because developmental improvements in verbatim processing simultaneously result in more true recognition and less false recognition in the phonological task. Our finding of a developmental increase in reporting of semantic false memories is of particular interest because it contradicts the typical developmental pattern of age decreases in errors of commission between early childhood and adolescence using a variety of methods such as the misinformation paradigm (e.g., Ceci, Ross, & Toglia, 1987; Holliday, Douglas & Hayes, 1999), word recognition (e.g., Brainerd & Reyna, 1996), and real life events (e.g., Pipe, Gee, Wilson, & Egerton, 1999), (for a comprehensive review, see Brainerd & Reyna, 2005).

FUTURE DIRECTIONS AND IMPLICATIONS FOR EDUCATION The phonological DRM task represents an excellent method for examining true and false 6 In a recent paper, Chan et al. (2005) proposed that their results provided evidence of the operation of ‘‘a phonological superiority effect’’. It should be noted, however, that because phonological and semantic words were presented in the same list, this finding could be the result of a conflation effect.


phonological memories in children with dyslexia. It is widely believed that dyslexic children have impoverished phonological memory. Goswami’s (2000) phonological representations hypothesis assumes that children with dyslexia have preexisting difficulties in the linguistic representations of the sequential sounds of speech, which leads to difficulties with printed word learning. The rime of a word is assumed to be the basic building block for the development of the lexicon (and by extension, literacy) among normally developing children (Bradley & Bryant, 1983). Therefore, children with dyslexia might be expected to show less activation at the level of the rime on tests of veridical and false recollection. A different prediction can be derived from Snowling’s (2001) theory of dyslexia, which assumes that dyslexia is characterised by impoverished representations for known words in long-term memory, thus preventing normal memory trace reactivation. This theory also assumes that awareness of the smaller units of a word, including the initial phoneme, can be critical for the development of literacy. Therefore, children with dyslexia might be expected to show less activation at the level of the head and initial phoneme (as well as the rime) when compared to normally developing readers. The pattern of sublexical effects on phonological recognition that we have identified here may be diagnostic (from a practical and a conceptual perspective) in the field of reading and writing difficulties. Preliminary data of ours indicate that dyslexic children have impaired phonological representations at the level of rime (Hamilton, Holliday, Weekes, Johnson, & Hutton, 2006). Importantly, these results confirm that the current remedial protocols used by education professionals that concentrate on improving dyslexics’ use of phonological representations of words are likely to be beneficial. Indeed, such training has been shown to improve reading in many dyslexics (Hatcher, Hulme, & Snowling, 2004; Hatcher, Helm, & Ellis, 1994). What are the implications of false memories for determining the accuracy of child eyewitness testimony? The DRM paradigm exemplifies several features of forensically relevant memories. For child witnesses of domestic violence, for example, such violence is not usually a single episode but rather a series of repeated events that are substantially similar but not exactly the same (Reyna et al., in press). It is the gist or the theme of these related events that is remembered, especially after a long delay between a witnessed

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event and giving testimony in court. Delays can range from a few months to several years (for illustrative cases, see Brainerd & Reyna, 2005; Ceci & Bruck, 1995; Reyna, 1998). After long delays, therefore, gist memories are used to remember both experienced events and nonexperienced but meaning consistent events (Reyna et al., in press). Hence, child witnesses should be interviewed with non-suggestive methods soon after a witnessed event (Holliday, 2003). However, in many real-world instances this is not achieved. Research that identifies factors known to affect children’s reports given under such conditions is crucial. Researchers have begun to delineate factors that are implicated in children’s abilities to use verbatim memories to reject false memories (e.g., age, short intervals between the event and recall) (Reyna et al., in press). Nonetheless, further research is crucial for our further understanding of the processes implicated in children’s false memories. Manuscript received 25 May 2005 Manuscript accepted 05 April 2006

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APPENDIX

Formulae for the measures of recognition sensitivity and response bias A? is the nonparametric counterpart of d? (Snodgrass & Corwin, 1988) and is calculated using one of two different formulae depending on the relationship between hit and false alarm rates. For this paper the single formula suggested by Stanislaw and Todorov (1999) was used, as follows: (H F)2 jH Fj A?0:5 sign(H F) 4max(H; F) 4HF where sign(H -F) equals /1 if H /F, 0 if H /F, and 1 if H B/F, and max(H , F) equals whichever is the greater of H and F. Where H /F for all

target/distractor combinations, A? was assigned the chance value of 0.5. The corresponding measure of response bias, B?D, proposed by Donaldson (1992), is given by: B?D /[(1 /H )(1 F )HF ]/[(1 H )(1 F )/HF ]. For target calculations, H was replaced with the proportion of hits for targets from presented lists, and F was the proportion of false alarms for unrelated distractors from non-presented lists. For critical lures, H was replaced with the proportion of hits for critical lures for presented lists, and F was the proportion of false alarms for unrelated critical lures from non-presented lists. For related distractors, H was replaced with the proportion of hits for related distractors for presented lists, and F was the mean of the false alarm rates for related and unrelated distractors from non-presented lists.