Verbal Short-term Memory Performance Research Articles

Morphosyntactic development in German-speaking individuals with Down syndrome-longitudinal data.

The present study provides longitudinal data on the development of receptive and expressive grammar in children and adolescents with Down syndrome and addresses the role of nonverbal cognitive abilities and verbal short-term memory for morphosyntactic development. Seventeen German-speaking individuals with Down syndrome (aged 4;6-17;1 years at first testing (T1)) were assessed twice, 4;4-6;6 years apart. For a subset of five participants, there was also a third assessment 2 years after the second. Receptive grammar, nonverbal cognition, and verbal short-term memory were tested using standardized measures. For expressive grammar, elicitation tasks were used to assess the production of subject-verb agreement and of wh-questions. At group level, the participants showed a significant increase in grammar comprehension from T1 to T2. However, progress diminished with increasing chronological age. Notable growth could not be observed beyond the age of 10 years.With respect to expressive grammatical abilities, progress was limited to those participants who had mastered verbal agreement inflection around age 10 years. Individuals who did not master verbal agreement by late childhood achieved no progress in producing wh-questions, either.There was an increase in nonverbal cognitive abilities in the majority of participants. Results for verbal short-term memory followed a similar pattern as those for grammar comprehension. Finally, neither nonverbal cognition nor verbal short-term memory were related to changes in receptive or expressive grammar. The results point to a slowdown in the acquisition of receptive grammar which starts before the teenage years. For expressive grammar, improvement in wh-question production only occurred in individuals with good performance in subject-verb agreement marking, which suggests that the latter might have a trigger function for further grammatical development in German-speaking individuals with Down syndrome. The study provides no indication that nonverbal cognitive abilities or verbal short-term memory performance determined the receptive or expressive development. The results lead to clinical implications for language therapy.

Short term memory in aphasia: effects of modality and relationship with Western Aphasia Battery-R performance

ABSTRACT Background Producing and comprehending language requires maintenance of linguistic units in short term memory (STM). While there is evidence of verbal STM impairments in persons with aphasia (PWA), there are unresolved questions about other aspects of STM in aphasia, particularly the role of input and output modalities on STM performance. This includes the extent to which visual STM abilities are impaired in PWA and if the modality of eliciting responses (verbal versus pointing) influences STM performance. A better understanding of the relationship between STM performance and clinical language assessments of PWA will inform test interpretation. Aims This study investigated three questions about short term memory (STM) performance in post-stroke aphasia: 1) whether visual STM is impaired in PWA given that a common neural network subserves encoding-recall of both verbal and visual STM, 2) whether the response modality (verbal vs pointing) impacts STM score, 3) the relationship between STM and language performance, specifically on the Western Aphasia Battery-Revised (WAB-R). Methods & Procedures Verbal and visuo-spatial performance on a STM battery was compared between 45 PWA and a representative neurotypical sample (N=40). For PWA, individual performance across STM subtasks was examined to identify dissociations and correlated with language performance on the WAB-R. Outcomes & Results PWA scored lower than neurotypical controls on verbal but not visual STM tasks. At the individual level, about one-half of PWA were impaired on the three verbal STM tasks, and one-third had dissociations among the three verbal STM tasks. There was no effect of response modality (verbal versus pointing) on verbal STM performance. There was a strong association between verbal STM and individual subtests of the WAB-R. In general, the relative phonological and semantic demands of the task (e.g. repetition) influenced the association strength with digit recall versus picture recall scores. Conclusions Verbal STM deficits are: 1) more prevalent than visual-spatial STM deficits in PWA, 2) strongly associated with WAB-R performance in a pattern that is consistent with the phonological and semantic demands of the tasks. The clinical implications of this study are that it is crucial to assess STM performance in PWA and examine its potential impact on language assessments. Further, a verbal or pointing response modality can be used for STM measurement without negatively impacting the score (unless there are clear motoric contra-indications). This study provides performance data for a set of aphasia-friendly STM tasks that can serve as future reference.

Neuropsychological and Neuroimaging Correlates of High-Altitude Hypoxia Trekking During the "Gokyo Khumbu/Ama Dablam" Expedition.

Committeri Giorgia, Danilo Bondi, Carlo Sestieri, Ginevra Di Matteo, Claudia Piervincenzi, Christian Doria, Roberto Ruffini, Antonello Baldassarre, Tiziana Pietrangelo, Rosamaria Sepe, Riccardo Navarra, Piero Chiacchiaretta, Antonio Ferretti, and Vittore Verratti. Neuropsychological and neuroimaging correlates of high-altitude hypoxia trekking during the "Gokyo Khumbu/Ama Dablam" expedition. High Alt Med Biol. 23:57-68, 2022. Background: Altitude hypoxia exposure may produce cognitive detrimental adaptations and damage to the brain. We aimed at investigating the effects of trekking and hypoxia on neuropsychological and neuroimaging measures. Methods: We recruited two balanced groups of healthy adults, trekkers (n = 12, 6 F and 6 M, trekking in altitude hypoxia) and controls (gender- and age-matched), who were tested before (baseline), during (5,000 m, after 9 days of trekking), and after the expedition for state anxiety, depression, verbal fluency, verbal short-term memory, and working memory. Personality and trait anxiety were also assessed at a baseline level. Neuroimaging measures of cerebral perfusion (arterial spin labeling), white-matter microstructural integrity (diffusion tensor imaging), and resting-state functional connectivity (functional magnetic resonance imaging) were assessed before and after the expedition in the group of trekkers. Results: At baseline, the trekkers showed lower trait anxiety (p = 0.003) and conscientiousness (p = 0.03) than the control group. State anxiety was lower in the trekkers throughout the study (p < 0.001), and state anxiety and depression decreased at the end of the study in both groups (p = 0.043 and p = 0.007, respectively). Verbal fluency increased at the end of the study in both groups (p < 0.001), whereas verbal short-term memory and working memory performance did not change. No significant differences between before and after the expedition were found for neuroimaging measures. Conclusions: We argue that the observed differences in the neuropsychological measures mainly reflect aspecific familiarity and learning effects due to the repeated execution of the same questionnaires and task. The present results thus suggest that detrimental effects on neuropsychological and neuroimaging measures do not necessarily occur as a consequence of short-term exposure to altitude hypoxia up to 5,000 m, especially in the absence of altitude sickness.

Occurrence of Reading Skills in a National Age Cohort of Norwegian Children with Down Syndrome: What Characterizes Those Who Develop Early Reading Skills?

Children with Down syndrome are at risk of reading difficulties. Reading skills are crucial for social and academic development, and thus, understanding the nature of reading in this clinical group is important. This longitudinal study investigated the occurrence of reading skills in a Norwegian national age cohort of 43 children with Down syndrome from the beginning of first grade to third grade. Data were collected to determine which characteristics distinguished those who developed early reading skills from those who did not. The children′s decoding skills, phonological awareness, nonverbal mental ability, vocabulary, verbal short-term memory, letter knowledge and rapid automatized naming (RAN) performance were measured annually. The results showed that 18.6% of the children developed early decoding skills by third grade. Prior to onset, children who developed decoding skills had a significantly superior vocabulary and letter knowledge than non-readers after controlling for nonverbal mental abilities. These findings indicate that early specific training that focuses on vocabulary and knowledge of words and letters may be particularly effective in promoting reading onset in children with Down syndrome.

Verbal learning impairment in adolescents with methamphetamine use disorder: a cross-sectional study

BackgroundMethamphetamine (MA) use has been shown to be associated with deficits in impulsivity, verbal learning, and working memory. Additionally, methamphetamine use disorder (MUD) is related to various brain changes, especially in adolescent users who might be more vulnerable to detrimental effects on brain development. However, little is known about the relationship between adolescent MA use and cognitive impairment. This cross-sectional study aims to explore how the presence of a MUD in adolescents is related to impairments of verbal memory, inhibition, and alertness.MethodsN = 18 psychiatric outpatients with MUD were matched in terms of depressivity, age, and gender to n = 18 adolescents with other substance use disorders (SUDs), as well as n = 18 controls without SUDs. We compared these three groups on the Verbal Learning and Memory Task (VLMT), and the alertness and go/noGo subtests of the Test of Attentional Performance (TAP). Additionally, Spearman’s rank order correlation coefficients were calculated to investigate whether cognitive functioning was directly associated with frequency of past year MA use.ResultsThe three groups differed significantly in their verbal learning performance (H (2) = 11.7, p = .003, ηp2 = .19), but not in short-term memory, inhibition, cued recall, or alertness. Post hoc tests revealed significant differences in verbal learning between the MA using group and the control group without a SUD (U = 56.5, p = .001, ηp2 = .31). Frequency of past year MA use correlated negatively with short-term memory (ρ = −.25, p < .01) and verbal learning (ρ = −.41, p < .01). No other cognitive variables correlated significantly with MA use frequency. Significant p-values were considered significant after Bonferroni correction.ConclusionsAdolescent MUD outpatients with regular MA use show specific impairment in verbal learning performance, but not in other basal cognitive functions when compared to adolescents without a MUD. Verbal learning and short-term memory performance is negatively associated with the frequency of MA use. Future research should apply longitudinal designs to investigate long-term effects of methamphetamine and reversibility of these effects on cognitive functioning.

The articulatory determinants of verbal sequence learning.

Two experiments (N = 154 in total) using the Hebb repetition effect-the enhancement of serial recall performance for a repeated sequence in among otherwise nonrepeated sequences-reveal a key role for active articulatory-planning processes in verbal sequence learning, contrary to a prominent, phonological-store based, model (Burgess & Hitch, 2006). First, Hebb sequence learning was attenuated when articulatory planning of the to-be-remembered sequence was restricted by articulatory suppression. This was less the case with auditory sequences, however, suggesting that passive perceptual organization processes operating independently of articulation also contribute to the learning of sequences presented auditorily. Second, sequence learning was enhanced for phonologically similar compared to dissimilar items when that learning was particularly reliant on articulatory planning (i.e., with visual sequences). That this enhanced learning was eliminated when articulatory planning was restricted also points to an articulatory basis for this 'phonological' similarity effect. Third, an inconsistent temporal grouping of items across instances of the repeating sequence also abolished learning but only when that grouping-based on independent evidence from output response-times during serial recall-was instantiated within an articulatory plan. These results are the first to suggest that verbal sequence learning, and not only verbal serial short-term memory (STM) performance, may be explicable by recourse to general-purpose articulatory and perceptual processes. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

The Link Between Verbal Short-Term Memory and Anomia Treatment Gains.

Purpose A significant relationship between verbal short-term memory (STM) and language performance in people with aphasia has been found across studies. However, very few studies have examined the predictive value of verbal STM in treatment outcomes. This study aims to determine if verbal STM can be used as a predictor of treatment success. Method Retrospective data from 25 people with aphasia in a larger randomized controlled trial of phonomotor treatment were analyzed. Digit and word spans from immediately pretreatment were run in multiple linear regression models to determine whether they predict magnitude of change from pre- to posttreatment and follow-up naming accuracy. Pretreatment, immediately posttreatment, and 3 months posttreatment digit and word span scores were compared to determine if they changed following a novel treatment approach. Results Verbal STM, as measured by digit and word spans, did not predict magnitude of change in naming accuracy from pre- to posttreatment nor from pretreatment to 3 months posttreatment. Furthermore, digit and word spans did not change from pre- to posttreatment or from pretreatment to 3 months posttreatment in the overall analysis. A post hoc analysis revealed that only the less impaired group showed significant changes in word span scores from pretreatment to 3 months posttreatment. Discussion The results suggest that digit and word spans do not predict treatment gains. In a less severe subsample of participants, digit and word span scores can change following phonomotor treatment; however, the overall results suggest that span scores may not change significantly. The implications of these findings are discussed within the broader purview of theoretical and empirical associations between aphasic language and verbal STM processing.

Testing the redintegration hypothesis by a single probe recognition paradigm

ABSTRACTThe lexicality effect in verbal short-term memory (STM), in which word lists are better recalled than nonwords lists, is considered to reflect the influence of linguistic long-term memory (LTM) knowledge on verbal STM performance. The locus of this effect remains, however, a matter of debate. The redintegrative account considers that degrading phonological traces of memoranda are reconstructed at recall by selecting lexical LTM representations that match the phonological traces. According to a strong version of this account, redintegrative processes should be strongly reduced in recognition paradigms, leading to reduced LTM effects. We tested this prediction by contrasting word and nonword memoranda in a fast encoding probe recognition paradigm. We observed a very strong lexicality effect, with better and faster recognition performance for words as compared to nonwords. These results do not support a strong version of the redintegrative account of LTM effects in STM which considers that these LTM effects would be the exclusive product of reconstruction mechanisms. If redintegration processes intervene in STM recognition tasks, they must be very fast, which at the same time provides support for models considering direct activation of lexico-semantic knowledge during verbal STM tasks.

Long-term associative learning predicts verbal short-term memory performance

Studies using tests such as digit span and nonword repetition have implicated short-term memory across a range of developmental domains. Such tests ostensibly assess specialized processes for the short-term manipulation and maintenance of information that are often argued to enable long-term learning. However, there is considerable evidence for an influence of long-term linguistic learning on performance in short-term memory tasks that brings into question the role of a specialized short-term memory system separate from long-term knowledge. Using natural language corpora, we show experimentally and computationally that performance on three widely used measures of short-term memory (digit span, nonword repetition, and sentence recall) can be predicted from simple associative learning operating on the linguistic environment to which a typical child may have been exposed. The findings support the broad view that short-term verbal memory performance reflects the application of long-term language knowledge to the experimental setting.

The effects of speech intelligibility and temporal–spectral variability on performance and annoyance ratings

Abstract Ambient sound can impair verbal short-term memory performance. This finding is relevant to the acoustic optimization of open-plan offices. Two algorithmic approaches claim to model the impairment during a given sound condition. One model is based on the Speech Transmission Index (STI). The other approach relies on the hearing sensation fluctuation strength ( F ). Within the scope of our consulting activities the approach based on F can hardly be applied and the model based on the STI is often misinterpreted in terms of semanticity. Therefore we put to test the two models and elucidate the relevance of temporal–spectral variability and semanticity of background sound with regard to impairment of performance. A group of 24 subjects performed a short-term memory task and rated perceived annoyance during eight different speech and speech-like noise conditions, which varied with regard to STI and F . The empirical data is compared to the model predictions, which only partly cover the experimental results. Speech impairs performance more than all other sound conditions and variable speech-like noise is more impairing than continuous speech-like noise. Sound masking with continuous speech-like noise provides relief from the negative effect of background speech. This positive effect is more pronounced if the signal to noise ratio is −3 dB(A) or even lower.

Interpreting potential markers of storage and rehearsal: Implications for studies of verbal short-term memory and neuropsychological cases.

Neuropsychological studies of verbal short-term memory have often focused on two signature effects - phonological similarity and word length - the absence of which has been taken to indicate problems in phonological storage and rehearsal respectively. In the present study we present a possible alternative reading of such data, namely that the absence of these effects can follow as a consequence of an individual's poor level of recall. Data from a large normative sample of 251 adult participants were re-analyzed under the assumption that the size of phonological similarity and word length effects are proportional to an individual's overall level of recall. For both manipulations, when proportionalized effects were plotted against memory span, the same function fit the data in both auditory and visual presentation conditions. Furthermore, two additional sets of single-case data were broadly comparable to those that would be expected for an individual's level of verbal short-term memory performance albeit with some variation across tasks. These findings indicate that the absolute magnitude of phonological similarity and word length effects depends on overall levels of recall, and that these effects are necessarily eliminated at low levels of verbal short-term memory performance. This has implications for how one interprets any variation in the size of these effects, and raises serious questions about the causal direction of any relationship between impaired verbal short-term memory and the absence of phonological similarity or word length effects.

Distraction in verbal short-term memory: Insights from developmental differences

The contribution of two mechanisms of auditory distraction in verbal serial short-term memory—interference with the serial rehearsal processes used to support short-term recall and general attentional diversion—was investigated by exploiting differences in auditory distraction in children and adults. Experiment 1 showed that serial rehearsal plays a role in children’s as well as adults’ distractibility: Auditory distraction from irrelevant speech was greater for both children and adults as the burden on rehearsal increased. This pattern was particularly pronounced in children, suggesting that underdeveloped rehearsal skill in this population may increase their distractibility. Experiment 2 showed that both groups were more susceptible to changing- than steady-state speech when the task involved serial rehearsal—indicating that both groups suffer interference-by-process—but that children, but not adults, were also susceptible to any sort of sound (steady or changing) in a task thought to be devoid of serial rehearsal. The overall pattern of results suggests that children’s increased susceptibility to auditory distraction during verbal short-term memory performance is due to a greater susceptibility to attentional diversion; in this view, under-developed rehearsal-skill increases children’s distractibility by exacerbating their under-developed attentional control rather than by increasing interference-by-process.

Memory integration in amnesia: Prior knowledge supports verbal short-term memory

Short-term memory (STM) and long-term memory (LTM) have traditionally been considered cognitively distinct. However, it is known that STM can improve when to-be-remembered information appears in contexts that make contact with prior knowledge, suggesting a more interactive relationship between STM and LTM. The current study investigated whether the ability to leverage LTM in support of STM critically depends on the integrity of the hippocampus. Specifically, we investigated whether the hippocampus differentially supports between-domain versus within-domain STM–LTM integration given prior evidence that the representational domain of the elements being integrated in memory is a critical determinant of whether memory performance depends on the hippocampus. In Experiment 1, we investigated hippocampal contributions to within-domain STM–LTM integration by testing whether immediate verbal recall of words improves in MTL amnesic patients when words are presented in familiar verbal contexts (meaningful sentences) compared to unfamiliar verbal contexts (random word lists). Patients demonstrated a robust sentence superiority effect, whereby verbal STM performance improved in familiar compared to unfamiliar verbal contexts, and the magnitude of this effect did not differ from that in controls. In Experiment 2, we investigated hippocampal contributions to between-domain STM–LTM integration by testing whether immediate verbal recall of digits improves in MTL amnesic patients when digits are presented in a familiar visuospatial context (a typical keypad layout) compared to an unfamiliar visuospatial context (a random keypad layout). Immediate verbal recall improved in both patients and controls when digits were presented in the familiar compared to the unfamiliar keypad array, indicating a preserved ability to integrate activated verbal information with stored visuospatial knowledge. Together, these results demonstrate that immediate verbal recall in amnesia can benefit from two distinct types of semantic support, verbal and visuospatial, and that the hippocampus is not critical for leveraging stored semantic knowledge to improve memory performance.

Grouping, semantic relation and imagery effects in individuals with Down syndrome.

Down syndrome (DS) is associated with a specific verbal short-term memory (STM) deficit. This study explored the effects of grouping, semantic relations and visual presentation upon verbal STM recall performance in a group of 15 individuals with DS and 15 vocabulary-matched typically developing (TD) children. Participants were presented with memoranda in either a temporally grouped schedule, such that items were grouped as pairs, or in an equally spaced presentation schedule. The two items constituting each pair were either semantically related or unrelated. Performance across these conditions was compared in verbal or verbal plus visual presentation modes. Significant memory recall benefits were observed across populations as a result of temporal grouping, semantic relations and verbal and visual combined presentation. However, a reduced benefit of semantic relation in the DS group compared to the TD group indicated that those with DS were less influenced by LTM relational knowledge. In addition, those with DS only experienced a grouping benefit during verbal and visual combined presentation, in contrast to the TD group who experienced grouping benefits throughout. This indicates that individuals with DS are poorer at encoding temporal context for purely verbal memoranda. These findings were replicated in a follow-up experiment, aimed at aligning baseline performance in the two populations. This study provides encouraging evidence that, despite their difficulties in some areas, individuals with DS can benefit from the use of grouping and LTM knowledge to assist their verbal STM performance under certain circumstances.

Demonstrating the effects of phonological similarity and frequency on item and order memory in Down syndrome using process dissociation

It is important to distinguish between memory for item information and memory for order information when considering the nature of verbal short-term memory (vSTM) performance. Although other researchers have attempted to make this distinction between item and order memory in children, none has done so using process dissociation. This study shows that such an approach can be particularly useful and informative. Individuals with Down syndrome (DS) tend to experience a vSTM deficit. These two experiments explored whether phonological similarity (Experiment 1) and item frequency (Experiment 2) affected vSTM for item and order information in a group of individuals with DS compared with typically developing (TD) vocabulary-matched children. Process dissociation was used to obtain measures of item and order memory via Nairne and Kelley’s procedure (Journal of Memory and Language, 50 (2004) 113–133). Those with DS were poorer than the matched TD group for recall of both item and order information. However, in both populations, phonologically similar items reduced order memory but enhanced item memory, whereas high-frequency items resulted in improvements in both item and order memory—effects that are in line with previous research in the adult literature. These results indicate that, despite poorer vSTM performance in DS, individuals experience phonological coding of verbal input and a contribution of long-term memory knowledge to recall. These findings inform routes for interventions for those with DS, highlighting the need to enhance both item and order memory. Moreover, this work demonstrates that process dissociation is applicable and informative for studying special populations and children.

Longitudinal and concurrent links between memory span, anxiety symptoms, and subsequent executive functioning in young children.

It has been conjectured that basic individual differences in attentional control influence higher-level executive functioning and subsequent academic performance in children. The current study sets out to complement the limited body of research on early precursors of executive functions (EFs). It provides both a cross-sectional, as well as a longitudinal exploration of the relationship between EF and more basic attentional control mechanisms, assessed via children's performance on memory storage tasks, and influenced by individual differences in anxiety. Multiple measures of verbal and visuospatial short-term memory (STM) were administered to children between 3 and 6 years old, alongside a non-verbal measure of intelligence, and a parental report of anxiety symptoms. After 9 months, children were re-tested on the same STM measures, at which time we also administered multiple measures of executive functioning: verbal and visuospatial working memory (WM), inhibition, and shifting. A cross-sectional view of STM development indicated that between 3 and 6 years the trajectory of visuospatial STM and EF underwent a gradual linear improvement. However, between 5 and 6 years progress in verbal STM performance stagnated. Hierarchical regression models revealed that trait anxiety was negatively associated with WM and shifting, while non-verbal intelligence was positively related to WM span. When age, gender, non-verbal intelligence, and anxiety were controlled for, STM (measured at the first assessment) was a very good predictor of overall executive performance. The models were most successful in predicting WM, followed by shifting, yet poorly predicted inhibition measures. Further longitudinal research is needed to directly address the contribution of attentional control mechanisms to emerging executive functioning and to the development of problematic behavior during early development.

The link between STM and sentence comprehension: A neuropsychological rehabilitation study

A memory rehabilitation study was conducted with two patients with contrasting impairments in verbal short-term memory (STM): one with impaired phonological STM (pSTM) and one with impaired semantic STM (sSTM). Two treatments were employed, each designed to improve separate aspects of STM: phonological and semantic. The pSTM treatment selectively improved sensitivity to phonological effects in STM, and the sSTM treatment brought about increased lexical effects on verbal STM performance. There was also some evidence of type-specific generalisation to sentence comprehension, in that the pSTM patient showed post-treatment improvement on sentence repetition after the pSTM treatment, and the sSTM patient showed improved sentence anomaly judgement after the sSTM but not the pSTM treatment. The findings are discussed in relation to theories on the components involved in STM, and the role of STM in sentence processing.

The impact of aging and hearing status on verbal short-term memory

ABSTRACTThe aim of this study is to assess the impact of hearing status on age-related decrease in verbal short-term memory (STM) performance. This was done by administering a battery of verbal STM tasks to elderly and young adult participants matched for hearing thresholds, as well as to young normal-hearing control participants. The matching procedure allowed us to assess the importance of hearing loss as an explanatory factor of age-related STM decline. We observed that elderly participants and hearing-matched young participants showed equal levels of performance in all verbal STM tasks, and performed overall lower than the normal-hearing young control participants. This study provides evidence for recent theoretical accounts considering reduced hearing level as an important explanatory factor of poor auditory-verbal STM performance in older adults.

The Development of Rehearsal in Verbal Short-Term Memory

Verbal short-term memory, as indexed by immediate serial recall tasks (in which participants must recall several stimuli in order, immediately after presentation), develops considerably across middle childhood. One explanation for this age-related change is that children's ability to rehearse verbal material increases during this period, and one particularly influential version of this account is that only older children engage in any form of rehearsal. In this article, we critique evidence that is used to support the claim of age-related change in rehearsal and also critique the argument that children do not rehearse when engaged in immediate serial recall. This is not to say that rehearsal does not develop with age or that it is not required in any task, but to suggest that it plays little role in the development of verbal short-term memory performance as traditionally measured.

Reevaluating key evidence for the development of rehearsal: Phonological similarity effects in children are subject to proportional scaling artifacts.

The size of an individual's phonological similarity effect for visually presented material is assumed to reflect his or her ability to recode, and by implication rehearse, information in verbal short-term memory. Many studies have shown that under these conditions, the size of this effect interacts with age, tending to be nonsignificant in children younger than 7 years and leading to the conclusion that children of this age do not rehearse. In the present study, the size of the phonological similarity effect was assessed in a total of 116 children aged between 5 and 9 years, manipulating the modality of both encoding and retrieval of the memoranda. Although the interaction between age and the size of the phonological similarity effect was replicated with visual presentation and verbal recall of material, this interaction was also present in other conditions that do not require recoding. In addition, the data from this "classic" condition were simulated by a model that assumed that the size of the similarity effect is (a) proportional to an individual's recall of dissimilar items and (b) constrained by a functional floor to recall of similar items. These findings undermine the evidence for a qualitative change in recoding and rehearsal at 7 years and question the extent to which rehearsal is necessary to explain the development of verbal short-term memory performance.