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# Development of false memories in 5- and 8-year-olds: The role of working memory maintenance mechanisms

Manon Rousselle, Agnès Blaye, Marlène Abadie

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## ► To cite this version:

Manon Rousselle, Agnès Blaye, Marlène Abadie. Development of false memories in 5- and 8-year-olds: The role of working memory maintenance mechanisms. Journal of Experimental Child Psychology, 2025, 254, 10.1016/j.jecp.2025.106206. hal-04974807

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# Development of false memories in 5- and 8-year-olds: The role of working memory maintenance mechanisms

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Manon Rousselle *, Agnès Blaye, Marlène Abadie *

Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Recherche en Psychologie et Neurosciences (CRPN), 13003 Marseille, France

## ARTICLE INFO

**Article history:**

Received 15 November 2024

Revised 17 January 2025

**Keywords:**

False memory

Developmental reversals

Working memory

Maintenance mechanisms

Long-term memory

Cognitive development

## ABSTRACT

Previous research has shown that false memories—that is, remembering things that did not happen but are consistent with the gist of the actual experiences—increase during development. The current study shows that this developmental reversal of false memory is moderated by the development of working memory (WM). In two experiments, 5- and 8-year-olds (N = 184; 103 girls; European) were asked to memorize lists of three or four semantically related words during retention intervals of a few seconds in which the opportunities to maintain the studied words in WM were varied. The children then performed an immediate recall test and a delayed recognition test. Experiment 1 showed that 8-year-olds made more semantic recall errors—that is, false memories—than non-semantic recall errors in the immediate test, whereas the opposite was true for 5-year-olds. Experiment 2, which introduced a stronger manipulation of WM maintenance, showed that 8-year-olds made more semantic errors than 5-year-olds in the immediate test when the opportunity to maintain the studied words in WM was reduced. This developmental reversal disappeared when children had more opportunities to maintain the studied words in WM. These results suggest that the development of WM maintenance mechanisms during childhood reduces the age-related increase in false memories.

© 2025 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

<footnote>* Corresponding authors.</footnote>

<footnote>E-mail addresses: manon.rousselle-jacquier@univ-amu.fr, manonroussellejacquier@gmail.com (M. Rousselle), marlene.abadie@univ-amu.fr (M. Abadie).</footnote>
## Introduction

Memory development is often seen as a process of permanent progression between birth and early adulthood. Memory capacity and processing speed increase, we remember more and more events in our lives with greater accuracy, and our memories become increasingly resistant to interference and suggestion (Schneider & Ornstein, 2015). However, it turns out that this progressive trend is not a universal feature of cognitive development. Under certain conditions, our ability to remember information accurately tends to get worse as we age (Brainerd & Reyna, 2023). For example, in the Deese-Roediger-McDermott (DRM) paradigm, participants are presented with word lists in which all the words (e.g., "climb, peak, ski, valley, etc.") are semantically related to an unpresented critical lure (e.g., "mountain") (Deese, 1959; Roediger & McDermott, 1995). Typically, adults show a higher rate of true memories for the studied words than children, but they also show a higher rate of false memories for the unpresented critical lures—a finding that has been referred to as a developmental reversal effect (see Brainerd et al., 2008, for a review). But how can processes that mature in a typical developmental pattern lead to an increase in memory errors with age?

Several interpretations have been proposed. The main one is that false memories are rooted in the formation of meaning connections between events, an ability that develops with age (e.g., Bjorklund, 1987). Developmental reversals in false memory research are usually obtained when many semantically related items are presented and memory is tested after a significant delay, that is, at least several minutes and often a day or more (Chang & Brainerd, 2021). Interestingly, however, a recent study has shown that this false memory illusion can occur as early as 4 years of age in working memory (WM) tasks where only a few related items are required to be remembered for an interval of only a few seconds (Rousselle et al., 2023). The error rate found in these tasks also appears to follow an ascending curve from late childhood into adulthood (Abadie & Rousselle, 2023). These new findings suggest that WM maintenance mechanisms may also play an important role in the emergence of false memories. WM is conceived as a capacity-limited system dedicated to the temporary maintenance of representations relevant to the ongoing task (Logie et al., 2021). Mechanisms for maintaining representations in WM undergo major changes during childhood (e.g., Spencer, 2020) and may contribute to the increase in false memories during development. However, no study to date has examined their influence on the developmental reversal effect of false memories. The aim of the current study was two-fold: first, to test whether the developmental reversal effect of false memories occurs in WM tasks between early and later childhood, and second, to examine the role of the development of WM maintenance mechanisms in this phenomenon.

### *Developmental reversals in false memory*

Many studies have shown that false memories increase between childhood and adulthood using DRM-like paradigms. In an initial study, Brainerd et al. (2002) showed that, after the presentation of 12-word DRM lists, false recall increased about fivefold (i.e., from 10% to 53%) and false recognition increased about 1.2-fold (i.e., from 77% to 92%) between 5-year-old children and young adults. Several additional experiments detected this age-related increase in false memories with the same paradigm regardless of whether the DRM lists were constructed from adult or child word association norms (e.g., Anastasi & Rhodes, 2008; Carneiro et al., 2007; Metzger et al., 2008).

Associative activation theory (AAT, Howe et al., 2009) and fuzzy-trace theory (FTT; e.g., Brainerd & Reyna, 2008) have proposed different yet mutually consistent explanations for this developmental reversal. We focused here on the FTT because, as will be shown, predictions about the emergence of false memories in adults' WM have been derived from this theory (e.g., Abadie & Campos, 2019). According to the FTT, episodic memories are represented by two independent types of traces: verbatim traces, which tag the specific details of an episode, and gist traces, which tag an episode's meaning/semantic features. In the DRM paradigm, participants can encode and retrieve verbatim representations of the literal form of words (e.g., their font size, position, and color) and gist representations of the semantic relations between them (e.g., synonymy, antonymy, taxonomic relations). In the memory test, gist retrieval supports false memories of meaning-consistent items (e.g., "mountain" for the list "climb, ski, peak, valley, etc."), whereas verbatim retrieval suppresses such errors. The FTT
predicts high rates of false memory in adults in this paradigm because DRM lists induce particularly strong gist memories for certain meanings. Developmental reversals occur because the ability to extract semantic relations between words in DRM lists improves substantially between early childhood and young adulthood. These predictions are supported by studies showing that manipulations that help children to connect meanings between items, or conversely to make it more difficult to process meaning relations between items, attenuate or eliminate age-related increases in false memories by either increasing false memories in young children or suppressing them in older children or adults (see Brainerd et al., 2008, for a review). Therefore, the question arises as to whether the false memories observed in WM tasks stem from the same processes as those observed in the DRM paradigm.

## False memory in WM tasks

A handful of studies have examined the role of WM in the emergence of false memories. A pioneering study by Atkins and Reuter-Lorenz (2008) reported fairly high false alarm rates (31%) for critical lures and increased reaction times for their correct rejection in a recognition task with 4-item DRM lists that was completed after a 3- to 4-s retention interval. These findings and those of subsequent studies (e.g., Flegal et al., 2010, 2014) suggest that false recognition errors can reliably occur within the temporal (i.e., after a few seconds of retention) and set size (i.e., for short memory lists) parameters characteristic of WM. Consistent with recent models that conceptualize WM as the activated part of long-term memory (LTM) (e.g., Cowan et al., 2021), the authors proposed that false memories may arise from common semantic processing mechanisms shared by WM and LTM.

However, other results do not entirely support this and show that false memories in WM tasks are more frequent when WM capacities are exceeded, suggesting that these errors, although occurring in WM tasks, are not the product of WM mechanisms. Sugrue and Hayne (2006) showed the usual age-related increase in false memories between 10-year-olds and young adults when using 14-word DRM lists, but this effect disappeared with 7-word lists. In addition, the memory errors of the young adults were reduced more for the shorter lists than the memory errors of the young children. Presumably, 7-word maintenance still places high attentional demands on young children's WM capacities, but less so for adults. Abadie and Camos (2019) conducted a series of experiments with young adults in which opportunities to maintain information in WM were varied and showed that false memories were more frequent when WM maintenance was impaired. Specifically, the highest false memory rates were obtained when the opportunities to maintain information through articulatory rehearsal, a mechanism that operates by the mere repetition of the items to be maintained (Camos et al., 2018), were reduced (31% on average) compared with when they were not (11.5% on average; see also Abadie et al., 2024; Macé & Caza, 2011; and Piroelle et al., 2025, for similar results). Moreover, this increase in false memories when articulatory rehearsal opportunities were reduced was accompanied by a drastic decrease in verbatim memory retrieval, measured with the simplified conjoint recognition (SCR) model, a multinomial processing tree model for estimating the contributions of verbatim and gist memory (Stahl & Klauer, 2008). These results suggest that WM maintenance mechanisms preserve the verbatim form of information rather than fomenting false memories.

Most of these studies have been conducted with young adults, and very few have looked at the occurrence of false memories in children. However, the ability to maintain verbal items in WM increases steadily between 2 years of age and late childhood (see Camos & Barrouillet, 2018, for a review). Whereas a 5-year-old can remember three words, a 9-year-old can remember four words and an 11-year-old can remember five (Hitch et al., 1989). To our knowledge, two studies have looked at short-term false memories in children and shown that they can occur as early as 4 years of age on WM tasks (Rousselle et al., 2023) and increase between 8 to 10 years of age and early adulthood (Abadie & Rousselle, 2023). Rousselle et al. (2023) asked 4- and 8-year-old children to memorize DRM 4- and 5-word lists, respectively, for a retention interval of 6 to 8 s for subsequent recognition. Gist-based false memories, estimated with the SCR model (Stahl & Klauer, 2008) were obtained in the 4- and 8-year-olds. However, this study did not clearly determine the role of WM maintenance mechanisms in the occurrence of false memories. Manipulating the opportunity to maintain information in WM proved to be ineffective in this study; that is, it did not affect either correct or false recognition in children in either age group. However, numerous other studies have shown that these mechanisms
become increasingly effective during childhood, particularly from 5 to 7 years of age, and contribute to the increase in storage capacity.

Articulatory rehearsal starts to be effective from 5 to 7 years of age, as evidenced by studies show-
ing that (a) phonological similarity and word length effects appear from age 6 in picture memory tasks
(Henry et al., 2012), (b) children begin to use overt verbalization to maintain pictures from the age 5 or
6 (Elliott et al., 2021), and (c) correct recall in verbal WM tasks decreases when a concurrent articu-
lation is introduced (Tam et al., 2010). A second mechanism for maintaining verbal information has
been described—attentional refreshing, which is assumed to reactivate memory traces in an executive
loop by paying attention to them; these traces are considered domain general (i.e., representing items
in their visual, auditory, semantic, or other form; Camos et al., 2018). Attentional refreshing begins to
be used effectively as early as 7 years of age and continues to increase in effectiveness up to 14 years of
age (Gaillard et al., 2011). This has been evidenced mainly by studies showing that varying the atten-
tional demand of a concurrent task has an impact on children's recall performance from 7 years of age
(e.g., Barrouillet et al., 2009; Camos & Barrouillet, 2011). The focus of these studies on the develop-
ment of WM maintenance mechanisms has been on correct recall or recognition performance, but
none has determined their role in the occurrence of false memories during childhood. This is exactly
what this study aimed to find out.

The current study

In two experiments, 5- and 8-year-old children completed a complex span task, which is a typical WM task, with short DRM-type lists followed by an immediate recall test and a delayed recognition test. These age groups were chosen because children are just beginning to use maintenance mechanisms at age 5, whereas they are effectively using them at age 8. A concurrent task of a few seconds was introduced between each word to vary the opportunity to maintain information in WM. In addition to assessing true and false memories, we also asked participants to report their subjective experience following each recall and used the SCR model to estimate the contributions of verbatim and gist representations to recognition responses.

We expected that 8-year-olds would produce more false memories than 5-year-olds in the imme-
diate test, as shown in a previous study on the development of short-term false memories comparing
children and adults (Abadie & Rousselle, 2023). As repeatedly shown in the classic DRM paradigm, we
also expected to observe more false memories in 8-year-olds than in 5-year-olds in the delayed test.
This developmental reversal would be accompanied by an increase in the retrieval of gist traces
(Brainerd & Reyna, 2023). With respect to the effect of manipulating the opportunity to maintain
information in WM, current data in young adults (e.g., Abadie & Camos, 2019) suggest that active
maintenance in WM prevents short-term false memories by preserving verbatim traces of the info-
mation. Therefore, we expected the developmental reversal of false memories to be greater in the
immediate test when WM maintenance was impaired than when it was not. False memories should
decrease in 8-year-olds when they have the opportunity to actively maintain information in WM,
but not in 5-year-olds for whom maintenance mechanisms are just beginning to develop. Finally,
we did not hypothesize how varying the use of WM maintenance mechanisms would affect the
delayed test. Although previous studies have shown an impact of these mechanisms on false memo-
ries in delayed tests in adults (e.g., Abadie & Camos, 2019; Abadie et al., 2024), this effect has not yet
been replicated in children (Rousselle et al., 2023).

Experiment 1

Method

Transparency and openness

The materials, deidentified data, sample size justification, statistical analysis scripts, and additional
statistical analyses for both experiments can be found on the Open Science Framework (OSF) page
(https://osf.io/c6m3x/?view_only=078af710329a4c33a6ca2c1e6381fa73). This study was not preregistered.

## Participants

In total, 46 5-year-olds (23 girls; $M_{age}$ = 67.26 months, $SD$ = 3.68) and 43 8-year-olds (26 girls; $M_{age}$ = 102.77 months, $SD$ = 3.24) were recruited in 2021 and 2022 from several preschools and elementary schools in France. Although we were not able to collect other demographic data, we assume that most participants in both experiments were of European origin and from middle to middle-high socioeconomic backgrounds given the location of the data collection. They were all French native speakers. Two participants from the 5-year-old group were excluded from the data analysis because they did not follow the instructions. For each participant, written parental consent was obtained. Ethical approval was obtained from the institutional review board of Aix-Marseille University.

## Materials

**Word lists.** We selected 12 lists of words semantically related to each other (e.g., "chicken, goat, cow, pig, tractor") and to a common theme (e.g., farm) from the lists used in Rousselle et al. (2023). They were recorded by a female voice via Audacity software (Audacity Team, 2016). Each list consisted of five semantically related words. To control for age-related differences in the attentional resources required to maintain a word, the number of words presented in each list was adjusted to the average memory span of each age group, with 5-year-olds presented with three words and 8-year-olds presented with four words (e.g., Hitch et al., 1989). Two different sets of word lists were created for each theme, and the words removed from each list varied from one set to the other to control that observed effects were not due to a specific word list. These sets were counterbalanced across participants. The unpresented words from each list served as related distractors in the delayed recognition test, as explained below. Two additional lists of semantically related words were added for the training phase. The 12 lists were divided into two groups of 6 lists that were randomly assigned to each of the two experimental conditions.

**Subjective experience.** During the recall phase, children were asked to choose one of three subjective judgments for each recalled word (see Ghetti et al., 2002, for a similar use of the three-option judgment in similar age groups). If they recalled a word that they thought they had heard, this recall was qualified as "heard." If they thought that the recalled word could be either a presented word or a word related in meaning to that of a presented word, this recall was qualified as "heard or related." Finally, if they recalled a word at random, this recall was qualified as "I don't know." This scale was designed to assess the type of memory trace likely to underlie both correct and incorrect recall. Drawing on the distinction proposed by the FTT among precise, specific, and fuzzier memory traces based on the retrieval of general meaning (e.g., Brainerd & Reyna, 2023), we assumed that a "heard" judgment could be associated with the retrieval of a precise memory trace, a "heard or related" judgment with a fuzzier meaning-based memory trace, and an "I don't know" judgment with a guess (see Abadie et al., 2024, and Piroelle et al., 2025, for a first use of this scale in a recall task with adults). To ensure that the children understood the three options, each judgment was accompanied by a visual representation. The "heard" judgment was accompanied by an image of an ear, the "heard or related" judgment by an image of a fuzzy ear, and the "I don't know" judgment by a drawing of an indecisive man. These images were found freely available on the internet.

**Delayed recognition test.** A list of 18 probe words was constructed including 6 targets (i.e., randomly selected words from the study phase lists), 6 related distractors (i.e., unpresented words from each studied list), and 6 unrelated distractors (i.e., unpresented words that were not related to any of the word lists). Each of the 12 studied word lists was associated with either a target or a related probe.

## Procedure

The experiment was displayed on a computer using E-Prime 3.0 software Version 3.0.3.82 (E-Prime Team, 2016). Fig. 1 illustrates one of the 12 trials of the task. Following the procedure used by Rousselle et al. (2023; see also Abadie & Rousselle, 2023), on each trial the theme of the list (e.g.,
"the farm") was presented to the children auditorily. The experimenter then pressed the spacebar to initiate the auditory presentation of the corresponding list of three or four words. The words were presented sequentially and randomly. When a word was uttered (M = 996 ms, SD = 196), the screen turned gray and lasted for 1750 ms for 8-year-olds and 2000 ms for 5-year-olds. This age adjustment was designed to control for age-related differences in processing speed (e.g., Towse & Hitch, 1995).

Between the presentation of two words, the children performed a concurrent task for 5300 ms. A 500-ms beep signaled the start of the concurrent task. On half of the 12 trials, the children performed a color naming task (Camos & Barrouillet, 2011). Children needed to identify the color of three smileys displayed for 1100 ms with a 500-ms interstimulus interval (ISI) for 8-year-olds or two smileys displayed for 1900 ms with a 500-ms ISI for 5-year-olds. The presentation time of each smiley was age-adjusted to control for age-related differences in processing speed. Presentation times were determined based on a previous study using a similar methodology (Rousselle et al., 2023). Children had to name aloud the color of each smiley (i.e., green, blue, or red) while pressing a corresponding colored key. For the other half of the trials, they performed a detection task. Circles appeared sequentially on the screen, and children were asked to press the spacebar for each one. The number and presentation time of each circle were similar to those of the smileys for each age group. The color naming task was more attentionally demanding than the detection task (e.g., Oftinger & Camos, 2017; 2018). Therefore, the children had fewer attentional resources to maintain the words during the color naming task. Furthermore, this task was performed aloud to avoid articulatory rehearsal of the words to be maintained (e.g., Oftinger & Camos, 2018). Thus, we assumed that the color naming task would impair the use of rehearsal and refreshing more than the detection task.

At the end of each trial, the children were asked to recall all the studied words. If they did not recall all the words, the experimenter first told them how many words were missing. Second, if they were still missing words, they were encouraged to give the words they thought they had heard. Then, they were invited to give any word they could think of. This forced-recall procedure was used to encourage participants to recall as many words as possible and to avoid disengagement from the task (see Abadie et al., 2024, for a similar procedure with young adults). Finally, the experimenter repeated the recalled words and asked the children to qualify each of them with one of the three judgments.

All trials with the detection task were presented sequentially, followed by all trials with the color naming task, or vice versa, counterbalanced across participants. The order of presentation of the lists within blocks was randomized for each participant. At the end of each block, the children performed a distraction task (i.e., copying the Rey figure; Rey, 1941) for 2 min. They then performed a delayed recognition test in which the different types of probes were presented auditorily in a sequential and random manner. Following the procedure used in Abadie and Camos's (2019) experiments, for each probe the children were asked whether they had heard it among the six studied lists. A "yes" response to this question was considered and recorded as a "target" response. If they answered "no," they were asked whether the probe could be related to the studied words. A "yes" response to this question was recorded as a "related distractor" response, and a "no" response was recorded as an "unrelated distractor" response. In total, three types of responses (i.e., target, related, and unrelated responses) were obtained for each probe type (i.e., target, related, and unrelated probes). A detailed description of the training phase preceding the experimental session is available on the OSF page. At the end of the experiment, the children were thanked for their participation and received a medal.

<figure><img src="image_7.png" /><figcaption>**Fig. 1.** Illustration of one trial of the color naming condition of the complex span task for 5-year-olds in Experiment 1. The name of the thematic category and the memory words were presented auditorily. On half of the trials, the children performed the color naming task as shown in the figure. In the other half of the trials, smileys were replaced by black circles (detection task). In the 8-year-old group, four words were presented for 1.75 s, and three smileys were presented for 1.1 s.</figcaption></figure>
## Results

Bayesian analyses were conducted using JASP Version 0.19 (JASP Team, 2024) with the default settings. The Bayes factor ($BF_{10}$) of each model was obtained by comparing its likelihood with that of the null model. First, we reported the best model, namely the model with the largest $BF_{10}$. Then, we reported the $BF_{inclusion}$ ($BF_{incl}$) value for effects included in the best model, which indicates the likelihood of each model including a given effect compared with all models stripped of that effect. The strength of the Bayes factors was interpreted based on Kass and Raftery (1995) norms.

### Immediate recall accuracy

Two independent and trained raters classified the responses to the recall test (i.e., correct recall, semantic errors, phonological errors, intrusions from previous studied lists, recall of the theme given before the presentation of a list, and other unrelated errors). Semantic errors (i.e., false memories) were incorrect recall of unpresented words semantically related to the theme of the studied list. and phonological errors were incorrect recall of words phonologically related to one of the words in the studied list. Interrater agreement was 94.4% before discussion between the raters, and full inter-rater agreement was achieved after discussion. Table 1 shows the percentages of each type of response.

**Correct recall.** A mixed-measures Bayesian analysis of variance (ANOVA) with age group (5 vs. 8 years) and concurrent task (detection vs. color naming) as factors was performed on correct recall. The best model was the additive model ($BF_{10} = 2.31 \times 10^{14}$). There was more correct recall in the detection condition than in the color naming condition ($BF_{incl} = 3.94 \times 10^{11}$) and for 8-year-olds than for 5-year-olds ($BF_{incl} = 563$), replicating the classic age advantage in recall performance in WM tasks and validating our manipulation of WM maintenance mechanisms.

**Recall errors.** Two mixed-measures Bayesian ANOVAs with age group and concurrent task as factors were conducted on semantic errors and aggregated non-semantic errors (i.e., phonological errors, intrusions, and other errors). For semantic errors, the best model included only the main effect of concurrent task ($BF_{10} = 5.01 \times 10^{5}$). There were more semantic errors in the color naming condition than in the detection condition. Contrary to our predictions, the analysis of effects provided weak evidence for the interaction between age and concurrent task on semantic errors ($BF_{incl} = .95$).

For non-semantic errors, the best model was the full model including the main effects of age and concurrent task and the interaction between the two variables ($BF_{10} = 1.03 \times 10^{6}$). There were more non-semantic errors in the color naming condition than in the detection condition ($BF_{incl} = 12.8$). The 5-year-olds made more non-semantic errors than the 8-year-olds ($BF_{incl} = 1.74 \times 10^{4}$). To decompose the age by concurrent task interaction ($BF_{incl} = 4.85$), Bayesian independent-samples *t* tests with age as factor were performed separately in each concurrent task condition. The analyses provided stronger

<caption>**Table 1**</caption>

Percentages of correct and incorrect recall (semantic errors, theme recall, phonological errors, intrusions, and other errors) as a function of age and concurrent task.

<table><thead><tr><th rowspan="2">Response type</th><th colspan="2">5-year-olds</th><th colspan="2">8-year-olds</th></tr><tr><th>Detection</th><th>Color naming</th><th>Detection</th><th>Color naming</th></tr></thead><tbody><tr><td>Correct recall</td><td>79.7 (17.1)</td><td>65.9 (18.3)</td><td>90.8 (9.2)</td><td>79.4 (11.2)</td></tr><tr><td>Incorrect recall</td><td></td><td></td><td></td><td></td></tr><tr><td>Semantic errors</td><td>7.1 (7.4)</td><td>11.6 (8.7)</td><td>7.4 (7.9)</td><td>15.8 (9.2)</td></tr><tr><td>Theme recall</td><td>5.9 (8.1)</td><td>8.6 (9.1)</td><td>0.7 (2.4)</td><td>3.1 (5.5)</td></tr><tr><td>Phonological errors</td><td>0.8 (1.9)</td><td>0.5 (1.6)</td><td>0.4 (1.5)</td><td>0.4 (1.5)</td></tr><tr><td>Intrusions</td><td>3.5 (7.3)</td><td>5.8 (9.9)</td><td>0.6 (1.5)</td><td>1.0 (3.0)</td></tr><tr><td>Other errors</td><td>3.0 (5.7)</td><td>7.6 (10.5)</td><td>0.2 (0.9)</td><td>0.4 (1.5)</td></tr></tbody></table>

*Note.* Standard deviations are in parentheses.
evidence for the age effect ($BF_{10} = 4.70 \times 10^3$) in the color naming condition than in the detection condition ($BF_{10} = 146$).

Finally, although there was no effect of age on semantic errors, a mixed-measures Bayesian ANOVA with age and error type (semantic vs. non-semantic) provided decisive evidence for an interaction between the two factors ($BF_{incl} = 1.15 \times 10^5$). The 8-year-olds made more semantic errors than non-semantic errors, whereas the 5-year-olds made more non-semantic errors than semantic errors. This result is consistent with the hypothesis of an increase in semantic errors at the expense of non-semantic errors with age.

**Subjective judgments.** Table 2 shows the percentage of each type of subjective judgment (heard, heard or related, and don't know) for each type of response (correct recall, semantic errors, and aggregated non-semantic errors) by age group and type of concurrent task. Several Bayesian ANOVAs were performed, first to compare the percentage of each type of judgment for each type of response and then to assess the effect of age and concurrent task on the percentage of each type of judgment for each type of response. For the sake of brevity, the main results are summarized here. The full results are available on the OSF page. For correct recall, “heard” judgments were the most frequent ($BF_{10s, U \ge 8.23 \times 10^{48}}$, being more frequent in 8-year-olds than in 5-year-olds ($BF_{incl} = 84$) and in the detection condition than in the color naming condition ($BF_{incl} = 1.31 \times 10^{11}$). For semantic errors, all judgments were equally frequent ($BF_{10} = 0.95$), and 8-year-olds made more “heard or related” judgments than 5-year-olds ($BF_{incl} = 131$). Finally, for non-semantic errors, “heard” and “don't know” judgments were more frequent than “heard or related” judgments ($BF_{10s, U \ge 13.10}$), and 5-year-olds made more judgments of both types than 8-year-olds ($BF_{10} = 6.80$ and $BF_{incl} = 112$, respectively).

## Delayed recognition accuracy

We computed discriminability indexes (Pr) for correct recognition of target probes and for false recognition of related probes to eliminate potential differences between age groups that would be related to the “yes” response bias (e.g., Brainerd et al., 2002). Pr indexes were obtained by subtracting the rate of incorrect recognition (i.e., “target” responses) of unrelated distractors from the rate of correct recognition of targets (true recognition) and from the rate of false recognition of related distractors as targets (false recognition). Pr indexes as a function of age and concurrent task are shown in Fig. 2. Two mixed-measures Bayesian ANOVAs were conducted on true and false recognition with age and concurrent task as factors. For true recognition, the best model included the main effects of age group and concurrent task ($BF_{10} = 19.80$). True recognition was higher in older children than in younger children ($BF_{incl} = 7.47$). There was also weak evidence that true recognition was higher in the detection condition than in the color naming condition ($BF_{incl} = 2.69$). For false recognition,

<caption>**Table 2**</caption>

Percentage of each type of subjective judgment (heard, heard or related, and don't know) associated with correct recall, semantic and non-semantic errors as a function of age, and concurrent task.

<table><thead><tr><th>Response type</th><th>Age group</th><th>Concurrent task</th><th>Heard</th><th>Heard or related</th><th>Don't know</th></tr></thead><tbody><tr><td rowspan="4">Correct recall</td><td rowspan="2">5 years</td><td>Detection</td><td>75.4 (21.5)</td><td>2.3 (7.0)</td><td>2.0 (7.7)</td></tr><tr><td>Color naming</td><td>62.6 (21.2)</td><td>1.5 (3.3)</td><td>1.8 (6.1)</td></tr><tr><td rowspan="2">8 years</td><td>Detection</td><td>89.1 (9.6)</td><td>0.9 (1.9)</td><td>0.8 (1.9)</td></tr><tr><td>Color naming</td><td>74 (12.4)</td><td>4 (5.8)</td><td>1.4 (2.5)</td></tr><tr><td rowspan="4">Semantic errors</td><td rowspan="2">5 years</td><td>Detection</td><td>4.2 (6.6)</td><td>0.5 (2.0)</td><td>2.4 (3.9)</td></tr><tr><td>Color naming</td><td>6.3 (7.9)</td><td>1.1 (3.3)</td><td>4.2 (6.1)</td></tr><tr><td rowspan="2">8 years</td><td>Detection</td><td>2 (4.8)</td><td>2.6 (4.2)</td><td>2.7 (3.7)</td></tr><tr><td>Color naming</td><td>3.8 (5.0)</td><td>5.5 (7.0)</td><td>6.5 (7.3)</td></tr><tr><td rowspan="4">Non-semantic errors</td><td rowspan="2">5 years</td><td>Detection</td><td>3.7 (7.6)</td><td>0</td><td>3.7 (7.4)</td></tr><tr><td>Color naming</td><td>5.7 (11.9)</td><td>1.3 (2.6)</td><td>7.1 (12.2)</td></tr><tr><td rowspan="2">8 years</td><td>Detection</td><td>0.9 (2.3)</td><td>0</td><td>0.3 (1.1)</td></tr><tr><td>Color naming</td><td>1.2 (2.5)</td><td>0.6 (1.9)</td><td>0</td></tr></tbody></table>

*Note.* Standard deviations are in parentheses.
although the false recognition rate was well above 0 for both age groups in both conditions (BF₁₀s ≥ 76.50), contrary to our prediction, the null model was the best (BF₁₀ = 1.00).

*Verbatim, gist memory, and guessing processes.* The multinomial SCR model (Stahl & Klauer, 2008) was used to compute parameter estimates for verbatim and gist memory for targets ($V_t$ and $G_t$, respectively) and for related probes ($V_r$ and $G_r$, respectively) and guessing parameters ($b$ and $a$). The parameters $V_t$ and $G_t$ represent the probability of retrieving a verbatim trace ($V_t$) or a gist trace ($G_t$) of a target when a target probe is presented at test. The parameters $V_r$ and $G_r$ correspond to the probability of retrieving a verbatim trace ($V_r$) or a gist trace ($G_r$) when a related probe is presented at test. The guessing parameter $b$ refers to the probability of guessing that a probe is either a target or a related probe, and the parameter $a$ refers to the probability of guessing that a probe is a target. Further information on the SCR model is available on the OSF page. Memory and guessing parameter estimates are given in Table 3. Hierarchical analyses were conducted using the latent trait approach (Klauer, 2010) implemented in the TreeBUGS software (Heck et al., 2018). Model fit was assessed with $T_1$ and $T_2$ statistics (Klauer, 2010). A posterior-predictive $p$ value (PPP) was obtained for each statistic. PPP values larger than .05 reflect satisfactory model fit (Schmidt et al., 2023). The model was satisfactory in all cases, with PPP ≥ .068 for all $T_1$ and $T_2$ statistics.

For each parameter, we computed a credible interval of the difference between 8-year-olds and 5-year-olds. The posterior samples obtained from the 8-year-olds were subtracted from those of the 5-year-olds, first overall and then in each concurrent task condition. The differences are shown in Table 4. Parameters for which the 95% credible interval of the difference estimate overlapped with 0 do not meaningfully differ (Smith & Batchelder, 2010). The only meaningful difference concerned the guessing parameter $b$, which was higher for 5-year-olds than for 8-year-olds in the detection condition.

## Discussion

Contrary to our predictions, there was no effect of age or interaction between age and concurrent task on semantic errors in the immediate test. However, 8-year-olds made more semantic errors than

<figure><img src="image_8.png" /><figcaption>**Fig. 2.** Discriminability index for true and false recognition as a function of age group and type of concurrent task in Experiment 1. Error bars represent 95% confidence intervals.</figcaption></figure>
<caption>**Table 3**</caption>

Parameter estimates for verbatim and gist memory and guessing processes as a function of age and concurrent task.

<table><thead><tr><th rowspan="2">Parameter</th><th colspan="2">5-year-olds</th><th colspan="2">8-year-olds</th></tr><tr><th>Detection</th><th>Color naming</th><th>Detection</th><th>Color naming</th></tr></thead><tbody><tr><td>V<sub>t</sub></td><td>.78 [.509, .943]</td><td>.66 [.421, .823]</td><td>.84 [.400, .988]</td><td>.88 [.019, .159]</td></tr><tr><td>V<sub>r</sub></td><td>.04 [.000, .173]</td><td>.03 [.000, .122]</td><td>.16 [.004, .533]</td><td>.19 [.011, .426]</td></tr><tr><td>G<sub>t</sub></td><td>.52 [.067, .929]</td><td>.58 [.075, .973]</td><td>.47 [.030, .944]</td><td>.60 [.075, .977]</td></tr><tr><td>G<sub>r</sub></td><td>.39 [.072, .750]</td><td>.29 [.041, .628]</td><td>.35 [.095, .570]</td><td>.48 [.090, .806]</td></tr><tr><td>b</td><td>.14 [.049, .258]</td><td>.07 [.008, .168]</td><td>.03 [.003, .094]</td><td>.08 [.019, .159]</td></tr><tr><td>a</td><td>.42 [.143, .740]</td><td>.46 [.049, .927]</td><td>.35 [.022, .848]</td><td>.35 [.176, .570]</td></tr></tbody></table>

Note. Parameter estimates are group-level means. The 95% Bayesian credible intervals are in brackets.

<caption>**Table 4**</caption>

Difference scores between 8-year-olds and 5-year-olds overall in the detection and color naming conditions.

<table><thead><tr><th rowspan="2">Parameter</th><th colspan="2">8-year-olds – 5-year-olds</th><th colspan="2">8-year-olds – 5-year-olds</th></tr><tr><th>Detection</th><th>Color naming</th><th>Detection</th><th>Color naming</th></tr></thead><tbody><tr><td>V<sub>t</sub></td><td>.15 [−.154, .399]</td><td>.07 [−.387, .400]</td><td>.23 [−.124, .491]</td><td></td></tr><tr><td>V<sub>r</sub></td><td>.10 [−.014, .288]</td><td>.13 [−.092, .504]</td><td>.16 [−.035, .401]</td><td></td></tr><tr><td>G<sub>t</sub></td><td>−.09 [−.753, .616]</td><td>−.05 [−.721, .644]</td><td>.03 [−.695, .714]</td><td></td></tr><tr><td>G<sub>r</sub></td><td>.01 [−.362, .360]</td><td>−.04 [−.470, .356]</td><td>.19 [−.323, .634]</td><td></td></tr><tr><td>b</td><td>−.04 [−.116, .038]</td><td><strong>−.11 [−.231, −.001]</strong></td><td>.013 [−.106, .117]</td><td></td></tr><tr><td>a</td><td>−.04 [−.457, .371]</td><td>−.07 [−.562, .490]</td><td>−.11 [−.645, .367]</td><td></td></tr></tbody></table>

Note. The 95% credible intervals are in brackets. Bolded difference scores excluded 0 from the 95% credible interval.

non-semantic errors, whereas the opposite was true for 5-year-olds. These semantic errors were more often associated with the judgment “heard or related,” reflecting the retrieval of fuzzy meaning-based traces, in 8-year-olds than in 5-year-olds.

The predicted increase in false memories and gist traces with age was not found in the delayed test. The lack of an age effect and of an interaction between age and concurrent task could be due to the insufficient difficulty of the latter. The high performance of all the children in this task, particularly in the color naming condition, suggests that it might not have been difficult enough to sufficiently reduce the opportunities to maintain items in WM. In Experiment 2, several methodological improvements were implemented to optimize the chances of detecting any potential age differences.

## Experiment 2

The second experiment was a conceptual replication of the first one, with three methodological improvements. First, the theme of the lists was no longer given before the presentation of the words to avoid it being considered a word to be remembered. Second, we increased the difficulty of the concurrent tasks by adding stimuli to be processed. Finally, additional training in the use of the subjective scale was added to ensure that the children understood it correctly. We expected that these methodological improvements would favor the emergence of the expected interaction between age and concurrent task in the immediate test and the increase in false memories with age in the delayed test.

### Method

### Participants

In total, 47 5-year-olds (24 girls; $M_{age}$ = 67.55 months, $SD$ = 4.96) and 48 8-year-olds (30 girls; $M_{age}$ = 103.35 months, $SD$ = 5.38) were recruited in several preschools and elementary schools in France. One participant from the 5-year-old group was excluded from the data analysis because the child did not follow the instructions.
## Materials and procedure

The materials and procedure of this experiment were similar to those of Experiment 1 except for four changes. First, the concurrent task difficulty was increased by adding stimuli (i.e., smileys or circles) to be processed. Three stimuli were displayed for 1350 ms and four stimuli were displayed for 950 ms, with a 250-ms ISI, for 5- and 8-year-olds, respectively. Second, the beep signal between the end of a word and the start of the concurrent task was reduced to 250 ms, and the word presentation time was limited to the word pronunciation time to avoid any possible word maintenance before the start of the concurrent task. Third, the name of the thematic category was no longer given at the beginning of each trial. Finally, a subjective scale training session, adapted from Lyons and Ghetti (2011), was added at the beginning of the experiment to ensure that children understood the judgments and could use them appropriately. A detailed explanation of the training is available on the OSF page.

## Results

### Immediate recall accuracy

Responses to the recall test were classified by the same raters as in Experiment 1. The response types were the same except that theme recall was considered as a semantic error. Interrater agreement was 96.5%, and full agreement was reached after discussion. Table 5 shows the percentages of each type of response.

**Correct recall.** A mixed-measures Bayesian ANOVA with age and concurrent task showed that the additive model was the best ($BF_{10} = 2 \times 10^{26}$). As in Experiment 1, correct recall was better in the detection condition than in the color naming condition ($BF_{incl} = 2.10 \times 10^{23}$) and for 8-year-olds than for 5-year-olds ($BF_{incl} = 7.53 \times 10^{3}$).

**Recall errors.** Two mixed-measures Bayesian ANOVAs were performed for semantic and non-semantic errors with age and concurrent task as factors. For semantic errors, the best model included the main effects of both factors and their interaction ($BF_{10} = 2.63 \times 10^{12}$). The 8-year-olds made more semantic errors than the 5-year-olds ($BF_{incl} = 6.97$). Semantic errors were more frequent in the color naming condition than in the detection condition ($BF_{incl} = 1.65 \times 10^{8}$). Importantly, as predicted, there was decisive evidence for an interaction between age and concurrent task ($BF_{incl} = 3.09 \times 10^{3}$). Bayesian independent-samples t tests with age as factor performed separately in each concurrent task condition revealed that 8-year-olds made more semantic errors than 5-year-olds in the color naming condition ($BF_{10} = 1.25 \times 10^{3}$). In contrast, there was substantial evidence against an age effect in the detection condition ($BF_{10} = 0.27$). Increasing the difficulty of the concurrent task in this experiment was sufficient to reveal the developmental reversal effect of false memories in the condition where there were fewer opportunities to maintain information in WM.

For non-semantic errors, the full model was again the best ($BF_{10} = 1.12 \times 10^{21}$). Non-semantic errors were more frequent in 5-year-olds than in 8-year-olds ($BF_{incl} = 2.24 \times 10^{7}$) and in the color naming errors.

<caption>**Table 5**</caption>

Percentage of correct and incorrect recall (semantic errors, phonological errors, intrusions and other errors) as a function of age and concurrent task.

<table><thead><tr><th rowspan="2">Response type</th><th colspan="2">5-year-olds</th><th colspan="2">8-year-olds</th></tr><tr><th>Detection</th><th>Color naming</th><th>Detection</th><th>Color naming</th></tr></thead><tbody><tr><td>Correct recall</td><td>80.6 (16.4)</td><td>51.6 (22.4)</td><td>92.2 (9.2)</td><td>69.4 (16.0)</td></tr><tr><td>Incorrect recall</td><td></td><td></td><td></td><td></td></tr><tr><td>Semantic errors</td><td>6.4 (7.1)</td><td>9.2 (7.7)</td><td>5.5 (5.5)</td><td>17.6 (10.0)</td></tr><tr><td>Phonological errors</td><td>0.4 (1.4)</td><td>0.8 (2.0)</td><td>0.4 (1.8)</td><td>0.8 (2.2)</td></tr><tr><td>Intrusions</td><td>6.9 (8.5)</td><td>19.9 (16.5)</td><td>1.5 (5.0)</td><td>6.4 (8.4)</td></tr><tr><td>Other errors</td><td>5.8 (8.9)</td><td>18.5 (17.2)</td><td>0.4 (1.3)</td><td>5.8 (6.6)</td></tr></tbody></table>

*Note.* Standard deviations are in parentheses.
ing condition than in the detection condition (BF<sub>incl</sub> = 2.25 × 10<sup>12</sup>). There was decisive evidence for the interaction between age and concurrent task type (BF<sub>incl</sub> = 229). Bayesian independent-samples *t* tests revealed that the age effect was greater in the color naming condition (BF<sub>10</sub> = 2.49 × 10<sup>6</sup>) than in the detection condition (BF<sub>10</sub> = 3.79 × 10<sup>3</sup>). Thus, reducing opportunities to use WM maintenance mechanisms increased non-semantic errors in 5-year-olds, whereas it increased semantic errors in 8-year-olds.

**Subjective judgments.** Table 6 shows the percentage of each type of subjective judgment for each type of response by age group and concurrent task type. As in Experiment 1, several Bayesian ANOVAs were performed, and the full results are reported on the OSF page. For the sake of brevity, only the main results are summarized here. For correct recall, “heard” judgments were the most frequent (BF<sub>10s, U</sub> ≥ 1.21 × 10<sup>55</sup>), being more frequent in 8-year-olds than in 5-year-olds (BF<sub>incl</sub> = 6.42 × 10<sup>3</sup>) and in the detection condition than in the color naming condition (BF<sub>incl</sub> = 5.35 × 10<sup>25</sup>). For semantic errors, all judgments were equally frequent (BF<sub>10</sub> = 1.03), and 8-year-olds made more “heard or related” and “don’t know” judgments than 5-year-olds, especially in the color naming condition (BF<sub>10</sub> = 38.60 and BF<sub>10</sub> = 21.00, respectively). Finally, for non-semantic errors, “heard” and “don’t know” judgments were more frequent than “heard or related” judgments (BF<sub>10s, U</sub> ≥ 2.93), and 5-year-olds made more judgments of both types than 8-year-olds (BF<sub>incl</sub> = 2.80 × 10<sup>3</sup> and BF<sub>incl</sub> = 40.80, respectively).

Delayed recognition accuracy

*Pr* indexes for true and false recognition are shown in Fig. 3. The mixed-measures Bayesian ANOVA with age and concurrent task on true recognition showed that the best model included only the main effect of concurrent task (BF<sub>10</sub> = 1.37 × 10<sup>5</sup>). True recognition was higher in the detection condition than in the color naming condition. For false recognition, the best model included only the main effect of age group with more false recognition in 8-year-olds, but the effect was weak (BF<sub>10</sub> = 1.93). However, a Bayesian one-sample *t* test provided evidence that the false recognition rate was no different from 0 in 5-year-olds (BF<sub>10</sub> = 0.34), in contrast to older children (BF<sub>10</sub> = 1.09 × 10<sup>4</sup>), thereby replicating the increase in false memories with age as shown in the classic version of the DRM paradigm.

*Verbatim, gist memory, and guessing processes.* Parameter estimates are given in Table 7. The model fit-ted the data well, with PPP ≥ .193 for all *T*<sub>1</sub> and *T*<sub>2</sub> statistics.

As in Experiment 1, for each parameter we computed a credibility interval of the difference between age groups (Table 8). Importantly for our hypotheses, gist memory for related distractors (*G*<sub>t</sub>) was greater for 8-year-olds than for 5-year-olds. In contrast, the guessing parameter *b* was greater for 5-year-olds than for 8-year-olds.

<caption>**Table 6**</caption>

Percentage of each type of subjective judgment (heard, heard or related and don't know) associated with correct recall, semantic and non-semantic errors as a function of age and concurrent task.

<table><thead><tr><th></th><th>Age group</th><th>Concurrent task</th><th>Heard</th><th>Heard or related</th><th>Don't know</th></tr></thead><tbody><tr><td rowspan="4">Correct recall</td><td rowspan="2">5 years</td><td>Detection</td><td>77.7 (19.2)</td><td>1.7 (4.5)</td><td>1.2 (3.5)</td></tr><tr><td>Color naming</td><td>47.6 (22.2)</td><td>2.2 (4.3)</td><td>1.8 (3.3)</td></tr><tr><td rowspan="2">8 years</td><td>Detection</td><td>90.8 (9.1)</td><td>1.2 (2.4)</td><td>0.2 (1.2)</td></tr><tr><td>Color naming</td><td>65 (15.6)</td><td>3.1 (4.1)</td><td>1.2 (2.6)</td></tr><tr><td rowspan="4">Semantic error</td><td rowspan="2">5 years</td><td>Detection</td><td>3.7 (5.5)</td><td>1.1 (2.5)</td><td>1.6 (4.2)</td></tr><tr><td>Color naming</td><td>4.6 (5.1)</td><td>1.6 (3.6)</td><td>3 (4.3)</td></tr><tr><td rowspan="2">8 years</td><td>Detection</td><td>2 (3.1)</td><td>1.4 (2.3)</td><td>2.1 (3.7)</td></tr><tr><td>Color naming</td><td>5.3 (7.4)</td><td>5.6 (7.1)</td><td>6.7 (6.3)</td></tr><tr><td rowspan="4">Non-semantic error</td><td rowspan="2">5 years</td><td>Detection</td><td>7 (11.3)</td><td>1.8 (4.5)</td><td>4.2 (7.4)</td></tr><tr><td>Color naming</td><td>18.4 (19.9)</td><td>8 (13.3)</td><td>12.9 (14.2)</td></tr><tr><td rowspan="2">8 years</td><td>Detection</td><td>0.9 (3.7)</td><td>0.6 (2.7)</td><td>0.9 (1.4)</td></tr><tr><td>Color naming</td><td>4.3 (6.4)</td><td>3.1 (5.4)</td><td>5.6 (8.8)</td></tr></tbody></table>

*Note.* Standard deviations are in parentheses.
<figure><img src="image_9.png" /><figcaption>**Fig. 3.** Discriminability index for true and false recognition as a function of age group and type of concurrent task in Experiment 2. Error bars represent 95% confidence intervals.</figcaption></figure>

## Discussion

As predicted, 8-year-olds made more semantic errors than 5-year-olds in the immediate test when opportunities to maintain information in WM were reduced. This developmental reversal disappeared in the condition where children had more opportunities to use WM maintenance mechanisms. In contrast, younger children made more non-semantic errors than older children in the immediate test, and this effect was more pronounced when maintenance opportunities were reduced. Finally, only 8-year-olds had a false memory rate greater than 0 in the delayed test, and they relied more heavily on gist memory to respond to a related distractor. These findings are discussed in more detail below.

## General discussion

The current study provides new insights into the developmental reversal of false memories between early and later childhood by examining their occurrence in WM tasks. Two experiments first demonstrated that the nature of errors made in a WM task evolves with age. Consistent with the

<table><caption>**Table 7**
Parameter estimates for verbatim and gist memory and guessing processes as a function of age and concurrent task.</caption><thead><tr><th rowspan="2">Parameter</th><th colspan="2">5-year-olds</th><th colspan="2">8-year-olds</th></tr><tr><th>Detection</th><th>Color naming</th><th>Detection</th><th>Color naming</th></tr></thead><tbody><tr><td>V<sub>t</sub></td><td>.77 [.559, .912]</td><td>.62 [.339, .841]</td><td>.96 [.849, .998]</td><td>.66 [.487, .807]</td></tr><tr><td>V<sub>r</sub></td><td>.04 [.001, .154]</td><td>.04 [.001, .135]</td><td>.24 [.014, .530]</td><td>.10 [.003, .308]</td></tr><tr><td>G<sub>t</sub></td><td>.55 [.057, .969]</td><td>.33 [.024, .805]</td><td>.76 [.191, .995]</td><td>.54 [.064, .957]</td></tr><tr><td>G<sub>r</sub></td><td>.08 [.004, .223]</td><td>.05 [.002, .185]</td><td>.30 [.067, .516]</td><td>.45 [.102, .724]</td></tr><tr><td>b</td><td>.16 [.046, .301]</td><td>.19 [.056, .365]</td><td>.04 [.004, .088]</td><td>.11 [.036, .192]</td></tr><tr><td>a</td><td>.23 [.012, .685]</td><td>.62 [.227, .934]</td><td>.18 [.008, .680]</td><td>.17 [.027, .412]</td></tr></tbody></table>

Note. Parameter estimates are group-level means. The 95% Bayesian credible intervals are in brackets.
<caption>**Table 8**</caption>

Difference scores between 8-year-olds and 5-year-olds overall in the detection and color naming conditions.

<table><thead><tr><th rowspan="2">Parameter</th><th colspan="2">8-year-olds – 5-year-olds</th><th>Detection</th><th>Color naming</th></tr><tr><th></th><th></th><th>8-year-olds – 5-year-olds</th><th>8-year-olds – 5-year-olds</th></tr></thead><tbody><tr><td>V<sub>t</sub></td><td>.19 [–.011, .436]</td><td></td><td><strong>.19 [.015, .411]</strong></td><td>.04 [–.240, .361]</td></tr><tr><td>V<sub>r</sub></td><td>.06 [–.055, .262]</td><td></td><td>.20 [–.053, .497]</td><td>.06 [–.082, .276]</td></tr><tr><td>G<sub>t</sub></td><td>.20 [–.521, .797]</td><td></td><td>.21 [–.504, .834]</td><td>.21 [–.450, .799]</td></tr><tr><td>G<sub>r</sub></td><td><strong>.42 [.139, .615]</strong></td><td></td><td>.22 [–.035, .463]</td><td><strong>.40 [.042, .685]</strong></td></tr><tr><td>b</td><td><strong>–.10 [–.214, –.003]</strong></td><td></td><td><strong>–.12 [–.274, –.001]</strong></td><td>–.081 [–.271, .080]</td></tr><tr><td>a</td><td>–.32 [–.715, .039]</td><td></td><td>–.04 [–.560, .506]</td><td><strong>–.45 [–.820, –.003]</strong></td></tr></tbody></table>

Note. The 95% credible intervals are in brackets. Bolded difference scores excluded 0 from the 95% credible interval.

developmental reversal effect in false memories, these errors become increasingly semantic with increasing age during childhood. Second, the use of WM maintenance mechanisms moderates this phenomenon. When opportunities to use WM maintenance mechanisms are reduced, semantic errors increase in older children, in contrast to younger children who make other types of errors. In the following, we discuss in turn the effect of age on false memory in the immediate and delayed tests and the role of WM maintenance in this phenomenon.

## Developmental reversal in false memories

Both experiments showed an increase in correct recall in the immediate test from 5 to 8 years of age, which was accompanied by an increase in semantic recall errors. The 8-year-olds made mostly semantic errors (78% and 64% in Experiments 1 and 2, respectively), whereas the 5-year-olds made a minority of semantic errors (34% and 26% in Experiments 1 and 2, respectively). These results show for the first time the developmental reversal of false memory in a WM task from 5 to 8 years of age when children need to maintain only a few items for a few seconds. They are complementary to those obtained previously showing an increase in false memory from 8 to 10 years of age and adulthood in a similar WM task (Abadie & Rousselle, 2023). Taken together, these findings suggest that, as in LTM (e.g., Brainerd & Reyna, 2023), the use of semantic representations in WM increases with age from 5 years to adulthood.

This complementary increase in short-term true and false memories during development is all the more interesting given that it contradicts the classical idea of compensation in memory development, according to which an increase in true memories should necessarily be accompanied by a decrease in memory errors. The notion of gist representations postulated by the FTT accounts for this pattern of findings because these representations are complementary; that is, they support both true and false memories (Brainerd et al., 2018). Thus, developmental improvements in gist memory may lead to both an increase in correct recall of studied items and an increase in semantic errors. Several results point to an increase in the use of gist memory during development in the immediate test of the current study. First, the nature of the errors made by the 5-year-olds, which—as in previous studies using the DRM paradigm in LTM tasks (Brainerd et al., 2002)—were predominantly intrusions of words from previous lists or recall of words unrelated to those presented, supports the idea that children at this age fail to extract the gist from the studied lists. Other studies using the DRM paradigm in LTM tasks (Dewhurst & Robinson, 2004) showed that 5-year-olds made predominantly phonological errors, suggesting a specific tendency to make phonological associations at this age. We did not replicate this effect here, where the phonological error rate was close to 0 despite the use of a WM task in which phonological processing could have been used to a greater extent than in an LTM task. This may be because the words used had little or no phonological association between them. Second, semantic errors associated with “heard or related” responses on the subjective scale increased with age. These responses can be equated with the subjective impression associated with gist retrieval. Although this result suggests that 5-year-olds rely less frequently on gist representations than 8-year-olds, it is also conceivable that younger children have less developed metacognitive abilities than older children,
which may prevent them from accurately reporting the specific type of representation they are retrieving.

The results of the delayed recognition test were more mixed. The effect of age on true and false memory occurred in one of the two experiments. The presence of the immediate test for each word list probably influenced responses to the delayed recognition test (see Chan et al., 2018, for a review). A *meta*-analysis of DRM experiments comparing recall-plus-recognition and recognition-only conditions showed that prior recall tests increased both false recognition of critical lures and correct recognition of the items studied in the delayed test (Gallo, 2006). There was also a correlation between false recall and subsequent false alarms in the recall-plus-recognition conditions. These results have been interpreted as being due to source monitoring errors (Roediger & McDermott, 1995)—participants confusing the experience of recalling critical distractors with their actual presentation—or to an increase in phantom recollection corresponding to the retrieval of details that accompanied the presentation of items falsely attributed to critical distractors (Brainerd et al., 2022). However, the experiments included in Gallo's (2006) *meta*-analysis all used DRM lists of 12 to 15 words, whereas the word lists used in our experiments were much shorter. Studies have shown that reducing the number of related words in DRM lists reduces the occurrence of false memories (e.g., Sugrue & Hayne, 2006). It is possible that the immediate test in our study, given the length of the word lists, favored the short-term retrieval and long-term retention of verbatim representations, which had the effect of reducing the false memory rates in the delayed test. Nevertheless, it is worth noting that, as predicted and in line with findings from LTM DRM studies (e.g., Brainerd et al., 2008), 8-year-olds made more false memories based on the retrieval of gist representations than younger children in the delayed test of Experiment 2.

*The use of WM maintenance mechanisms moderates developmental reversal in false memories*

In Experiment 1, reducing opportunities to use WM maintenance mechanisms increased both semantic and non-semantic errors in the immediate test in 5-year-olds, whereas semantic errors were mainly increased in 8-year-olds. In Experiment 2, where the difficulty of the concurrent task was increased, 8-year-olds made more semantic errors in the immediate test than 5-year-olds when maintenance opportunities were reduced, whereas 5-year-olds made more non-semantic errors than older children. There was no difference in semantic errors as a function of age when more maintenance opportunities were available, with semantic errors decreasing in older children. However, 5-year-olds still made more non-semantic errors than 8-year-olds. These results show for the first time that the developmental reversal of short-term false memories occurs specifically when opportunities to maintain information in WM are reduced. Thus, short-term false memories do not appear to arise from the use of WM maintenance mechanisms given that their emergence is favored when maintenance opportunities are reduced, particularly in older children who are most likely to use them.

Consistent with previous findings in adults (Abadie & Camos, 2019; Abadie et al., 2024), these results rather suggest that the use of WM maintenance mechanisms facilitates the retrieval of verbatim representations of studied items and reduces the occurrence of false memories. In support of this hypothesis, other studies using a divided attention method—that is, a method similar in some respects to the manipulation of WM maintenance opportunities—have also shown that the retrieval of verbatim representations increases when full attention is available (e.g., Greene & Naveh-Benjamin, 2022, 2023; Odegard & Lampinen, 2005). The retrieval of these representations increases with age and the development of WM maintenance mechanisms. As predicted by the FTT (Brainerd et al., 2008), gist representations develop in parallel. These are mobilized when verbatim representations are difficult to access, such as when opportunities to maintain information in WM are reduced, leading to an increase in false memories. This is particularly true for older children, who are better able to extract gist representations from information than younger children. Congruently, the current study showed that reducing opportunities to maintain information in WM in younger children, who presumably have fewer gist representations, increased all types of errors, with no specific effect on semantic errors.

In the delayed test, true recognition was higher when children had more opportunities to maintain information in WM. There was no effect of manipulating WM maintenance opportunities on false
memory. Nevertheless, in Experiment 2 the retrieval of gist representations for related distractors was increased in 8-year-olds relative to 5-year-olds when WM maintenance opportunities were reduced. These results mimicked those of the immediate test, which showed an increase in gist representations in older children when WM maintenance opportunities were reduced.

## Limitations and perspectives

The current study is not without its limitations. First, we made methodological choices, such as equating the number of memory words to the average memory span of each age group, to ensure that our results reflect the influence of WM maintenance mechanisms, but this also has its drawbacks. In particular, the extra word per list that older children needed to maintain compared with younger children, may have favored gist memory retrieval and the occurrence of false memories in the former group. A previous study showed that 14-word DRM lists produced more false memories than 7-word lists in 9- and 10-year-olds and young adults (Sugrue & Hayne, 2006). Note, however, that the number of memory words in Sugrue and Hayne's (2006) study was doubled, and the increase in false memories was much greater in young adults than in children. In addition, a recent study examined the occurrence of false memories in 4- and 8-year-olds using a WM task similar to the current study (Rousselle et al., 2023). In Experiment 1 children were asked to maintain the same number of words regardless of age, and in Experiment 2 the number of words was age-adjusted, as in the current study. The effect of age on false memory and gist retrieval was similar in both experiments, suggesting that the difference in the number of words to be maintained between age groups has no (or minimal) effect on the rate of false memory and gist retrieval. Future studies could overcome this methodological aspect by presenting DRM word lists of increasing length, which would allow both the measurement of each child's memory span and an examination of the length at which false memories begin to emerge for each age group.

A second limitation, as mentioned above, concerns the results of the delayed test, which are difficult to interpret because of the presence of the immediate test. As designed, the experiments in the current study were unable to distinguish the effects of immediate testing from those of manipulating the use of WM maintenance mechanisms on delayed test performance. To answer this question, future studies should focus specifically on the effect of WM maintenance mechanisms on the occurrence of false memories in a delayed test.

## Concluding comments

An impressive body of research has now shown that susceptibility to false memory increases dramatically with age. The current study demonstrated the importance of the first few seconds of information maintenance in WM for the occurrence of this developmental reversal. Specifically, it revealed that the use of mechanisms to maintain information in WM reduces the age-related increase in false memories by decreasing these errors more in older children, who use WM maintenance mechanisms more effectively, than in younger children. These findings suggest that the development of WM maintenance mechanisms enables the preservation of verbatim representations of studied items and reduces the occurrence of semantic errors in the short term. From a theoretical perspective, this study highlights the importance of investigating the role of the development of WM maintenance mechanisms to better understand the emergence of false memories during childhood. From a practical perspective, it emphasizes the importance of ensuring that children's WM is not overloaded with contextual or other information that may hold little relevance when interviewing children in clinical or forensic settings.

## CRediT authorship contribution statement

**Manon Rousselle:** Writing – review & editing, Writing – original draft, Visualization, Software, Methodology, Investigation, Formal analysis, Data curation, Conceptualization. **Agnès Blaye:** Writing – review & editing, Supervision, Methodology, Conceptualization. **Marlène Abadie:** Writing – review
& editing, Writing – original draft, Visualization, Supervision, Project administration, Methodology, Funding acquisition, Formal analysis, Data curation, Conceptualization.

## Data availability

The material, raw data, statistical analysis scripts and additional analyses are available on the OSF page dedicated to the article.

## Acknowledgments

This work was supported by a grant from the French National Research Agency (ANR-19-CE28-0017-01) to Marlène Abadie. The funding source was not involved in the conduct of the research or in the preparation of the article. We thank Anaelle Quemeneur for her assistance with data collection.

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