The phonological store of working memory: is it phonological and is it a store?

The phonological store of working memory: A critique and an alternative, perceptual-motor, approach to verbal short-term memory

A key quality of a good theory is its fruitfulness, one measure of which might be the degree to which it compels researchers to test it, refine it, or offer alternative explanations of the same empirical data. Perhaps the most fruitful element of Baddeley and Hitch's (1974) Working Memory framework has been the concept of a short-term phonological store, a discrete cognitive module dedicated to the passive storage of verbal material that is architecturally fractionated from perceptual, language, and articulatory systems. This review discusses how the phonological store construct has served as the main theoretical springboard for an alternative perceptual-motor approach in which serial-recall performance reflects the opportunistic co-opting of the articulatory-planning system and, when auditory material is involved, the products of obligatory auditory perceptual organisation. It is argued that this approach, which rejects the need to posit a distinct short-term store, provides a better account of the two putative empirical hallmarks of the phonological store-the phonological similarity effect and the irrelevant speech effect-and that it shows promise too in being able to account for nonword repetition and word-form learning, the supposed evolved function of the phonological store. The neuropsychological literature cited as strong additional support for the phonological store concept is also scrutinised through the lens of the perceptual-motor approach for the first time and a tentative articulatory-planning deficit hypothesis for the "short-term memory" patient profile is advanced. Finally, the relation of the perceptual-motor approach to other "emergent-property" accounts of short-term memory is briefly considered.

The song that never ends: The effect of repeated exposure on the development of an earworm

An "earworm"-the experience of a catchy melody that repeats persistently in the mind-is a ubiquitous yet mysterious cognitive phenomenon. Previous research demonstrates that earworms for vocal music engage working memory resources, manifesting as "inner singing." This study investigated whether this effect is moderated by prior exposure to music. In one experimental session, participants (N = 44) were presented with four novel song choruses. To manipulate exposure, each song was presented between one and four times, counterbalanced across participants. The following day, participants undertook a serial recall task during and following presentation of each song. In addition, they rated the music on familiarity, enjoyment, their desire to sing along, and perceived catchiness, both before and following the experiment. Increased exposure to novel songs on the first day tended to result in greater interference on task performance during and following their presentation on the second day, yet the effect varied depending on the song. Ratings of the desire to sing along and perceived familiarity increased significantly between the sessions for all songs. These findings are important in understanding the relative influence of familiarity and song-level characteristics on the development of an earworm.

Differences between Monolinguals and Bilinguals in Phonetic and Phonological Learning and the Connection with Auditory Sensory Memory

Bilingualism has been linked with improved function regarding certain aspects of linguistic processing, e.g., novel word acquisition and learning unfamiliar sound patterns. Two non mutually-exclusive approaches might explain these results. One is related to executive function, speculating that more effective learning is achieved through actively choosing relevant information while inhibiting potentially interfering information. While still controversial, executive function enhancements attributed to bilingual experience have been reported for decades. The other approach, understudied to date, emphasizes the role of sensory mechanisms, specifically auditory sensory memory. Bilinguals outperformed monolinguals in tasks involving auditory processing and episodic memory recall, but the questions whether (1) bilinguals' auditory sensory memory skills are also enhanced, and (2) phonetic skill and auditory sensory memory are correlated, remain open, however. Our study is innovative in investigating phonetic learning skills and auditory sensory memory in the same speakers from two groups: monolinguals and early bilinguals. The participants were trained and tested on an artificial accent of English and their auditory sensory memory was assessed based on a digit span task. The results demonstrated that, compared to monolinguals, bilinguals exhibit enhanced auditory sensory memory and phonetic and phonological learning skill, and a correlation exists between them.

Task-specific auditory distraction in serial recall and mental arithmetic

Previous studies suggest that task-irrelevant changing-state sound interferes specifically with the processing of serial order information in the focal task (e.g., serial recall from short-term memory), whereas a deviant sound in the auditory background is supposed to divert central attention, thus producing distraction in various types of cognitive tasks. Much of the evidence for this distinction rests on the observed dissociations in auditory distraction between serial and non-serial short-term memory tasks. In this study, both the changing-state effect and the deviation effect were contrasted between serial digit recall and mental arithmetic tasks. In three experiments (two conducted online), changing-state sound was found to disrupt serial recall, but it did not lead to a general decrement in performance in different mental arithmetic tasks. In contrast, a deviant voice in the stream of irrelevant speech sounds did not cause reliable distraction in serial recall and simple addition/subtraction tasks, but it did disrupt a more demanding mental arithmetic task. Specifically, the evaluation of math equations (multiplication and addition/subtraction), which was combined with a pair-associate memory task to increase the task demand, was found to be susceptible to auditory distraction in participants who did not serially rehearse the pair-associates. Together, the results support the assumption that the interference produced by changing-state sound is highly specific to tasks that require serial-order processing, whereas auditory deviants may cause attentional capture primarily in highly demanding cognitive tasks (e.g., mental arithmetic) that cannot be solved through serial rehearsal.

Verbal interference paradigms: A systematic review investigating the role of language in cognition

This paper presents a systematic review of the empirical literature that uses dual-task interference methods for investigating the on-line involvement of language in various cognitive tasks. In these studies, participants perform some primary task X putatively recruiting linguistic resources while also engaging in a secondary, concurrent task. If performance on the primary task decreases under interference, there is evidence for language involvement in the primary task. We assessed studies (N = 101) reporting at least one experiment with verbal interference and at least one control task (either primary or secondary). We excluded papers with an explicitly clinical, neurological, or developmental focus. The primary tasks identified include categorization, memory, mental arithmetic, motor control, reasoning (verbal and visuospatial), task switching, theory of mind, visual change, and visuospatial integration and wayfinding. Overall, the present review found that covert language is likely to play a facilitative role in memory and categorization when items to be remembered or categorized have readily available labels, when inner speech can act as a form of behavioral self-cuing (inhibitory control, task set reminders, verbal strategy), and when inner speech is plausibly useful as "workspace," for example, for mental arithmetic. There is less evidence for the role of covert language in cross-modal integration, reasoning relying on a high degree of visual detail or items low on nameability, and theory of mind. We discuss potential pitfalls and suggestions for streamlining and improving the methodology.

EXPRESS: Translating words into actions in working memory: the role of spatial-motoric coding

Research from a working memory perspective on the encoding and temporary maintenance of sequential instructions has established a consistent advantage for enacted over verbal recall. This is thought to reflect action planning for anticipated movements at the response phase. We describe five experiments investigating this, comparing verbal and enacted recall of a series of action–object pairings under different potentially disruptive concurrent task conditions, all requiring repetitive movements. A general advantage for enacted recall was observed across experiments, together with a tendency for concurrent action to impair sequence memory performance. The enacted recall advantage was reduced by concurrent action for both fine and gross concurrent movement with the degree of disruption influenced by both the complexity and the familiarity of the movement. The results are discussed in terms of an output buffer store of limited capacity capable of holding motoric plans for anticipated action.

Less motor (re-)planning requires fewer working memory resources

In the current study, we asked if less motor re-planning requires fewer resources in working memory (WM). To this end, participants executed a spatial WM task in parallel to different sequential motor tasks: (1) a randomised task with a high amount of motor re-planning and (2) an ordered task with a lower amount of motor re-planning. Recall performance in the spatial WM task was measured as the dependent variable. Hand posture was used to calculate the percentage of motor re-planning and, thus, to validate the experimental manipulation. The percentage of motor re-planning was lower in the ordered task, while spatial WM performance was higher. This indicates that WM resources depleted by the motor task scale with the amount of motor re-planning. Results further showed a significant recency effect (i.e. better recall of late items) in the spatial WM task. As previous studies found that recency effects in a verbal WM task are disrupted by a concurrent motor task, the presence of recency in the current study indicates a differential interference of a concurrent motor task on verbal vs. spatial recall, which has important implications for several current models of WM.

Doubts About the Role of Rehearsal in the Irrelevant Sound Effect

Abstract. The irrelevant sound effect (ISE) describes the disruption of processes involved in maintaining information in working memory (WM) when irrelevant noise is present in the environment. While some posit that the ISE arises due to split obligation of attention to the irrelevant sound and the to-be-remembered information, others have argued that background noise corrupts the order of information within WM. Support for the latter position comes from research showing that the ISE appears to be most robust in tasks that emphasize ordered maintenance by a serial rehearsal strategy, and diminished when rehearsal is discouraged or precluded by task characteristics. This prior work confounds the demand for seriation with rehearsal. Thus, the present study aims to disentangle ordered maintenance from a rehearsal strategy by using a running memory span task that requires ordered output but obviates the utility of rehearsal. Across four experiments, we find a significant ISE that persists under conditions that should discourage the use of rehearsal and among individuals who self-report use of alternative strategies. These findings indicate that rehearsal is not necessary to produce an ISE in a serial recall task and thus fail to corroborate accounts of the ISE that emphasize the involvement of rehearsal.

Comprehension of Morse Code Predicted by Item Recall From Short-Term Memory

Purpose Morse code as a form of communication became widely used for telegraphy, radio and maritime communication, and military operations, and remains popular with ham radio operators. Some skilled users of Morse code are able to comprehend a full sentence as they listen to it, while others must first transcribe the sentence into its written letter sequence. Morse thus provides an interesting opportunity to examine comprehension differences in the context of skilled acoustic perception. Measures of comprehension and short-term memory show a strong correlation across multiple forms of communication. This study tests whether this relationship holds for Morse and investigates its underlying basis. Our analyses examine Morse and speech immediate serial recall, focusing on established markers of echoic storage, phonological-articulatory coding, and lexical-semantic support. We show a relationship between Morse short-term memory and Morse comprehension that is not explained by Morse perceptual fluency. In addition, we find that poorer serial recall for Morse compared to speech is primarily due to poorer item memory for Morse, indicating differences in lexical-semantic support. Interestingly, individual differences in speech item memory are also predictive of individual differences in Morse comprehension. Conclusions We point to a psycholinguistic framework to account for these results, concluding that Morse functions like "reading for the ears" (Maier et al., 2004) and that underlying differences in the integration of phonological and lexical-semantic knowledge impact both short-term memory and comprehension. The results provide insight into individual differences in the comprehension of degraded speech and strategies that build comprehension through listening experience. Supplemental Material https://doi.org/10.23641/asha.16451868.

Transfer of working memory training to the inhibitory control of auditory distraction

Extended working memory training with the dual n-back task has been shown to improve performance on various untrained cognitive tasks, but previous findings were inconsistent with regard to the extent of such transfer. The dual n-back training task addresses multiple components of working memory as sequential information from two different stimulus modalities needs to be simultaneously encoded, maintained, continuously monitored and updated in working memory while irrelevant information needs to be inhibited. However, it is unclear which executive functions account for the observed transfer effects. In this study, the degree of inhibitory control required during training was manipulated by comparing two versions of the dual n-back task in which participants are asked to either respond or withhold a response on the less frequent trials when an item was identical to an item n trials back. Eight 80-min sessions of training with adaptive versions of both n-back tasks were shown to improve working memory updating. Moreover, in contrast to the standard n-back task, training on the inhibitory n-back task was found to reduce the interference in working memory produced by task-irrelevant speech. This result suggests that enhanced demand for inhibitory control during training enables transfer to the inhibition of distractor interference, whereas the standard n-back task primarily affects working memory updating. The training effects did not transfer to the inhibition of spatially incompatible responses in a Simon task, and it yielded no far transfer effects to untrained executive functions or measures of fluid intelligence.

Verbal Working Memory as Emergent from Language Comprehension and Production

This article reviews current models of verbal working memory and considers the role of language comprehension and long-term memory in the ability to maintain and order verbal information for short periods of time. While all models of verbal working memory posit some interaction with long-term memory, few have considered the character of these long-term representations or how they might affect performance on verbal working memory tasks. Similarly, few models have considered how comprehension processes and production processes might affect performance in verbal working memory tasks. Modern theories of comprehension emphasize that people learn a vast web of correlated information about the language and the world and must activate that information from long-term memory to cope with the demands of language input. To date, there has been little consideration in theories of verbal working memory for how this rich input from comprehension would affect the nature of temporary memory. There has also been relatively little attention to the degree to which language production processes naturally manage serial order of verbal information. The authors argue for an emergent model of verbal working memory supported by a rich, distributed long-term memory for language. On this view, comprehension processes provide encoding in verbal working memory tasks, and production processes maintenance, serial ordering, and recall. Moreover, the computational capacity to maintain and order information varies with language experience. Implications for theories of working memory, comprehension, and production are considered.

Dissociating the Disruptive Effects of Irrelevant Music and Speech on Serial Recall of Tonal and Verbal Sequences

Task-irrelevant speech or music sounds are known to disrupt verbal short-term memory even when participants are instructed to ignore the sound, suggesting that automatically processed acoustical changes interfere with the rehearsal of phonological items. However, much less is known about auditory distraction in tasks that require the memorization and recall of non-phonological auditory items. In the present study, both musically trained and untrained participants were asked to memorize random tone sequences (consisting of low, medium, and high pitch tones) while task-irrelevant sound was presented. Irrelevant instrumental music was found to produce more disruption of tonal recall than white noise, whereas irrelevant speech produced intermediate levels of disruption. In contrast, only speech produced significant interference in an analogous verbal recall task. Crucially, although musically trained participants were able to recall more tones in general, the degree of auditory distraction that was produced by irrelevant music in the tonal recall task was found to be independent of musical expertise. The findings are in line with the assumption of two separate mechanisms for the maintenance of tonal and phonological information. Specifically, short-term memory for tone sequences may rely on a pitch-based rehearsal system which is disrupted by the perception of irrelevant pitch changes as contained in instrumental music (and to a lesser extent in speech), whereas serial recall of verbal items is most sensitive to phonological sounds.

Auditory distraction does more than disrupt rehearsal processes in children's serial recall

As children mature, their ability to remember information improves. This improvement has been linked to changes in verbal control processes such as rehearsal. Rehearsal processes are thought to undergo a quantitative shift around 7 years of age; however, direct measurement of rehearsal is difficult. We investigated a measure of rehearsal ability in children and compared this measurement to serial recall performance in the presence of auditory distractors. Theories of auditory distraction effects in children rely upon a combination of attentionally based and serial-order-based processes (Elliott et al. in Journal of Memory and Language, 88, 39-50, 2016); the present work contributes to the understanding of auditory distraction effects by measuring both types of processes within one study. Children completed an individually adjusted serial-recall task with auditory distractors. To assess rehearsal, each child's proportionalized articulatory difference (PAD) score was calculated from performance on adaptive digit span tasks performed in quiet and under articulatory suppression (see also Jarrold & Citroën in Developmental Psychology, 49, 837-847, 2013). Attentional processes were measured in two ways: first, by using complex span tasks, and second, by children's vulnerability to disruption in the context of irrelevant sound. The results indicated that the rehearsal measure was significantly related to the auditory distraction effect, but this relation was isolated to the attentional-diversion component of the irrelevant-sound effect. The results provide preliminary evidence that children consume attentional resources during rehearsal. Moreover, irrelevant sound disrupts children's rehearsal not solely through automatic, obligatory conflict. Rather, irrelevant sound diverts children's attention, which prevents attentional resources from supporting rehearsal processes.

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.

Phonological recoding under articulatory suppression

We report data from an experiment in which participants performed immediate serial recall of visually presented words with or without articulatory suppression, while also performing homophone or rhyme detection. The separation between homophonous or rhyming pairs in the list was varied. According to the working memory model (Baddeley, 1986; Baddeley & Hitch, 1974), suppression should prevent articulatory recoding. Nevertheless, rhyme and homophone detection was well above chance. However, with suppression, participants showed a greater tendency to false-alarm to orthographically related foils (e.g., GIVE–FIVE). This pattern is similar to that observed in short-term memory patients.

In the Beginning Was the Deed: Verbal Short-Term Memory as Object-Oriented Action

Our goal is not to present a new theory of verbal short-term memory (vSTM), but to supplant the concepts used to explain performance on vSTM tasks for some 60 years. We view the concepts of vSTM and its concomitant processes as reifications from observations of performance on these tasks. Millennia of refining, elaborating, and utilizing symbolic systems for representing the putative sounds of speech has seduced researchers into viewing verbal behavior as embodying the hallmarks of these systems, setting verbal material apart from other types of physical material with which people interact. Contrarily, we maintain that verbal material should be seen in the same light as other material. The way in which people encounter and manipulate it (e.g., in the microcosm of the vSTM setting) is to be understood with respect to processes that organize material into perceptual objects that may then be apprehended and manipulated by bodily effector systems. We outline how key empirical hallmarks of vSTM yield to this approach.

Overt language production plays a key role in the Hebb repetition effect

When asked to recall verbatim a short list of items, performance is very limited. However, if the list of items is repeated across trials, recall performance improves. This phenomenon, known as the Hebb repetition effect (Hebb, 1961; Brain Mechanisms and Learning: A Symposium, pp. 37-51), is considered a laboratory analogue of language learning. In effect, learning a new word implies the maintenance of a series of smaller units, such as phonemes or syllables, in the correct order for a short amount of time before producing them. The sequence of smaller units is typically presented more than once. In the present study, we investigated the role of overt language production in language learning by manipulating recall direction. If the learning of a repeated list of items relies on overt language production processes, changing list production order by manipulating recall direction should impact the learning of the list. In Experiment 1, one list was repeated every third trial, and recall direction of the repeated list changed on the ninth repetition. In Experiment 1a, the repeated list changed from a forward to a backward order recall, where participants had to recall the items in reverse presentation order. In Experiment 1b, the repeated list changed from a backward to a forward order recall. Results showed a cost in recall performance for the repeated list when recall direction switched from forward to backward recall, whereas it was unaffected by the change from backward to forward recall. In Experiment 2, we increased the number of trials before introducing the change from a backward to a forward order recall. Results showed a decrement in recall performance for the repeated list following the change in recall direction, suggesting that language production processes play a role in the Hebb repetition effect.

Shared Processing of Language and Music

The present study sought to explore whether musical information is processed by the phonological loop component of the working memory model of immediate memory. Original instantiations of this model primarily focused on the processing of linguistic information. However, the model was less clear about how acoustic information lacking phonological qualities is actively processed. Although previous research has generally supported shared processing of phonological and musical information, these studies were limited as a result of a number of methodological concerns (e.g., the use of simple tones as musical stimuli). In order to further investigate this issue, an auditory interference task was employed. Specifically, participants heard an initial stimulus (musical or linguistic) followed by an intervening stimulus (musical, linguistic, or silence) and were then asked to indicate whether a final test stimulus was the same as or different from the initial stimulus. Results indicated that mismatched interference conditions (i.e., musical - linguistic; linguistic - musical) resulted in greater interference than silence conditions, with matched interference conditions producing the greatest interference. Overall, these results suggest that processing of linguistic and musical information draws on at least some of the same cognitive resources.

The phonological loop unmasked? A comment on the evidence for a “perceptual-gestural” alternative

Jones et al. (Jones, Hughes, & Macken, 2006; Jones, Macken, & Nicholls, 2004) identify the interaction between phonological similarity, articulatory suppression, and stimulus presentation mode in verbal short-term memory as potentially providing important support for the phonological loop hypothesis. They find such an interaction but attribute it to “perceptual organization masquerading as phonological storage”. We present data using shorter letter sequences and find clear evidence of the interaction predicted by the phonological loop hypothesis, which, unlike the evidence of Jones et al., is not limited to recency, and which provides continued support for the phonological loop hypothesis.

Common modality effects in immediate free recall and immediate serial recall

In 2 experiments, participants were presented with lists of between 2 and 12 words for either immediate free recall (IFR) or immediate serial recall (ISR). Auditory recall advantages at the end of the list (modality effects) and visual recall advantages early in the list (inverse modality effects) were observed in both tasks and the extent and magnitude of these effects were dependent upon list length. Both tasks displayed modality effects with short lists that were large in magnitude but limited to the final serial position, consistent with those observed in the typically short lists used in ISR, and both tasks displayed modality effects with longer lists that were small in magnitude and more extended across multiple end-of-list positions, consistent with those observed in the typically longer lists used in IFR. Inverse modality effects were also observed in both tasks at early list positions on longer lengths. Presentation modality did not affect where recall was initiated, but modality effects were greatest on trials where participants initiated recall with the first item. We argue for a unified account of IFR and ISR. We also assume that the presentation modality affects the encoding of all list items, and that modality effects emerge due to the greater resistance of auditory items to output interference. (PsycINFO Database Record

The role of overt language production in the Hebb repetition effect

The Hebb repetition effect (Hebb, 1961) occurs when recall performance improves for a list that is repeated during a serial-recall task. This effect is considered a good experimental analogue to language learning. Our objective was to evaluate the role of overt language production in language learning by manipulating recall direction during a Hebb repetition paradigm. In each trial, seven nonsense syllables were presented auditorily. Participants had to orally recall the items either in the presentation order or in reverse order. One sequence was repeated every third trial. In Experiment 1, we compared learning from a group that had recalled the items in their presentation order to learning from a group that had recalled the items in the reverse order. The two groups yielded similar learning rates. In Experiment 2, recall direction was varied between trials. The learning rate was not affected when recall direction varied between trials, suggesting a limited role of overt language production in language learning.

Recalling visual serial order for verbal sequences

We report three experiments in which participants performed written serial recall of visually presented verbal sequences with items varying in visual similarity. In Experiments 1 and 2 native speakers of Japanese recalled visually presented Japanese Kanji characters. In Experiment 3, native speakers of English recalled visually presented words. In all experiments, items varied in visual similarity and were controlled for phonological similarity. For Kanji and for English, performance on lists comprising visually similar items was overall poorer than for lists of visually distinct items across all serial positions. For mixed lists in which visually similar and visually distinct items alternated through the list, a clear “zig-zag” pattern appeared with better recall of the visually distinct items than for visually similar items. This is the first time that this zig-zag pattern has been shown for manipulations of visual similarity in serial-ordered recall. These data provide new evidence that retaining a sequence of visual codes relies on similar principles to those that govern the retention of a sequence of phonological codes. We further illustrate this by demonstrating that the data patterns can be readily simulated by at least one computational model of serial-ordered recall, the Primacy model (Page and Norris, Psychological Review, 105(4), 761–81, 1998). Together with previous evidence from neuropsychological studies and experimental studies with healthy adults, these results are interpreted as consistent with two domain-specific, limited-capacity, temporary memory systems for phonological material and for visual material, respectively, each of which uses similar processes that have evolved to be optimal for retention of serial order.

A matter of emphasis: Linguistic stress habits modulate serial recall

Models of short-term memory for sequential information rely on item-level, feature-based descriptions to account for errors in serial recall. Transposition errors within alternating similar/dissimilar letter sequences derive from interactions between overlapping features. However, in two experiments, we demonstrated that the characteristics of the sequence are what determine the fates of items, rather than the properties ascribed to the items themselves. Performance in alternating sequences is determined by the way that the sequences themselves induce particular prosodic rehearsal patterns, and not by the nature of the items per se. In a serial recall task, the shapes of the canonical “saw-tooth” serial position curves and transposition error probabilities at successive input–output distances were modulated by subvocal rehearsal strategies, despite all item-based parameters being held constant. We replicated this finding using nonalternating lists, thus demonstrating that transpositions are substantially influenced by prosodic features—such as stress—that emerge during subvocal rehearsal.

Have We Forgotten Auditory Sensory Memory? Retention Intervals in Studies of Nonverbal Auditory Working Memory

Researchers have shown increased interest in mechanisms of working memory for nonverbal sounds such as music and environmental sounds. These studies often have used two-stimulus comparison tasks: two sounds separated by a brief retention interval (often 3-5 s) are compared, and a "same" or "different" judgment is recorded. Researchers seem to have assumed that sensory memory has a negligible impact on performance in auditory two-stimulus comparison tasks. This assumption is examined in detail in this comment. According to seminal texts and recent research reports, sensory memory persists in parallel with working memory for a period of time following hearing a stimulus and can influence behavioral responses on memory tasks. Unlike verbal working memory studies that use serial recall tasks, research paradigms for exploring nonverbal working memory-especially two-stimulus comparison tasks-may not be differentiating working memory from sensory memory processes in analyses of behavioral responses, because retention interval durations have not excluded the possibility that the sensory memory trace drives task performance. This conflation of different constructs may be one contributor to discrepant research findings and the resulting proliferation of theoretical conjectures regarding mechanisms of working memory for nonverbal sounds.

The Mid-Career Award

Working memory is an extremely influential concept within experimental psychology, with, at the time of writing, over 90 papers with this term in their title published in this journal alone since 2000. One reason for this interest is that measures of working memory tend to be strong correlates of important indices of real-world function. In addition, at first sight working memory appears to be a relatively simple concept to understand. However, despite this apparent simplicity, explaining working memory performance is not straightforward. In this paper I address this challenge, with a particular focus on the development of working memory performance in children; both children developing typically and those experiencing atypical development. I specifically highlight the multiple constraints on working memory performance, and how these constraints inter-relate. I then consider the broader theoretical implications of each of these constraints for current accounts of working memory and its development.

Speak, Act, Remember

The fields of language production and verbal memory have relatively little contact. I argue that utterance planning for language production has substantial memory maintenance demands and that utterance planning provides the maintenance and ordering processes for short-term verbal memory tasks. There has already been some movement toward this view. I discuss benefits to pursuing these links more fully.

Storing Verbal Information in Working Memory

Recent reexaminations of the storage of verbal information in working memory have distinguished two mechanisms of maintenance. While a language-based mechanism of rehearsal was long considered the specific means of maintaining verbal information in the short term, another attention-based mechanism of refreshing has been more recently described. New evidence has established that these two mechanisms are affected by different constraints inherent to their respective language-based and attentional natures, have different impacts on recall performance, and are sustained by distinct brain networks. Moreover, adults can use either one or the other mechanism based on strategic choice or instructions. This dissociation presents some similarities with a dichotomy put forward in the ’70s between mechanisms permitting short-term versus long-term maintenance, but many questions remain about the functioning of these mechanisms and their interplay.

A motor similarity effect in object memory

In line with theories of embodied cognition (e.g., Versace et al. European Journal of Cognitive Psychology, 21, 522-560, 2009), several studies have suggested that the motor system used to interact with objects in our environment is involved in object recognition (e.g., Helbig, Graf, & Kiefer Experimental Brain Research, 174, 221-228, 2006). However, the role of the motor system in immediate memory for objects is more controversial. The objective of the present study was to investigate the role of the motor system in object memory by manipulating the similarity between the actions associated to series of objects to be retained in memory. In Experiment 1, we showed that lists of objects associated to dissimilar actions were better recalled than lists associated to similar actions. We then showed that this effect was abolished when participants were required to perform a concurrent motor suppression task (Experiment 2) and when the objects to be memorized were unmanipulable (Experiment 3). The motor similarity effect provides evidence for the role of motor affordances in object memory.

A motor isolation effect: When object manipulability modulates recall performance

Previous studies suggested that the language production architecture is recruited during verbal retention, and others proposed that spatial memory relies on the oculomotor system. The objective of the present study was to investigate the role of the motor system in object memory, by examining the effect of objects’ affordances on retention. In a serial recall task, we manipulated the manipulability of objects to retain in memory. We used an isolation paradigm where we isolated the manipulability level of one object from the list. We showed that recall performance improved for the isolated object (Experiment 1) and that this advantage was abolished when participants were required to perform motor suppression during the task (Experiment 2). In Experiment 3, we showed that the abolition of the motor isolation effect in Experiment 2 was not due to an effect of distraction since motor suppression was shown not to interfere with a semantic isolation effect. It is argued that motor affordances play a role in object memory, but only when the motor characteristics of an object allow discriminating it from the other objects in the list.

Language and short-term memory: the role of perceptual-motor affordance

The advantage for real words over nonwords in serial recall--the lexicality effect--is typically attributed to support for item-level phonology, either via redintegration, whereby partially degraded short-term traces are "cleaned up" via support from long-term representations of the phonological material or via the more robust temporary activation of long-term lexical phonological knowledge that derives from its combination with established lexical and semantic levels of representation. The much smaller effect of lexicality in serial recognition, where the items are re-presented in the recognition cue, is attributed either to the minimal role for redintegration from long-term memory or to the minimal role for item memory itself in such retrieval conditions. We show that the reduced lexicality effect in serial recognition is not a function of the retrieval conditions, but rather because previous demonstrations have used auditory presentation, and we demonstrate a robust lexicality effect for visual serial recognition in a setting where auditory presentation produces no such effect. Furthermore, this effect is abolished under conditions of articulatory suppression. We argue that linguistic knowledge affects the readiness with which verbal material is segmentally recoded via speech motor processes that support rehearsal and therefore affects tasks that involve recoding. On the other hand, auditory perceptual organization affords sequence matching in the absence of such a requirement for segmental recoding and therefore does not show such effects of linguistic knowledge.

Memory mechanisms supporting syntactic comprehension

Efforts to characterize the memory system that supports sentence comprehension have historically drawn extensively on short-term memory as a source of mechanisms that might apply to sentences. The focus of these efforts has changed significantly in the past decade. As a result of changes in models of short-term working memory (ST-WM) and developments in models of sentence comprehension, the effort to relate entire components of an ST-WM system, such as those in the model developed by Baddeley (Nature Reviews Neuroscience 4: 829-839, 2003) to sentence comprehension has largely been replaced by an effort to relate more specific mechanisms found in modern models of ST-WM to memory processes that support one aspect of sentence comprehension--the assignment of syntactic structure (parsing) and its use in determining sentence meaning (interpretation) during sentence comprehension. In this article, we present the historical background to recent studies of the memory mechanisms that support parsing and interpretation and review recent research into this relation. We argue that the results of this research do not converge on a set of mechanisms derived from ST-WM that apply to parsing and interpretation. We argue that the memory mechanisms supporting parsing and interpretation have features that characterize another memory system that has been postulated to account for skilled performance-long-term working memory. We propose a model of the relation of different aspects of parsing and interpretation to ST-WM and long-term working memory.

Do irrelevant sounds impair the maintenance of all characteristics of speech in memory?

Several studies have shown that maintaining in memory some attributes of speech, such as the content or pitch of an interlocutor's message, is markedly reduced in the presence of background sounds made of spectrotemporal variations. However, experimental paradigms showing this interference have only focused on one attribute of speech at a time, and thus differ from real-life situations in which several attributes have to be memorized and maintained simultaneously. It is possible that the interference is even greater in such a case and can occur for a broader range of background sounds. We developed a paradigm in which participants had to maintain the content, pitch and speaker size of auditorily presented speech information and used various auditory distractors to generate interference. We found that only distractors with spectrotemporal variations impaired the detection, which shows that similar interference mechanisms occur whether there are one or more speech attributes to maintain in memory. A high percentage of false alarms was observed with these distractors, suggesting that spectrotemporal variations not only weaken but also modify the information maintained in memory. Lastly, we found that participants were unaware of the interference. These results are similar to those observed in the visual modality.

Construction of a Memory Battery for Computerized Administration, Using Item-Response Theory

In accordance with Item Response Theory, a computer memory battery with six tests was constructed for use in the Portuguese adult population. A factor analysis was conducted to assess the internal structure of the tests ( N = 547 undergraduate students). According to the literature, several confirmatory factor models were evaluated. Results showed better fit of a model with two independent latent variables corresponding to verbal and non-verbal factors, reproducing the initial battery organization. Internal consistency reliability for the six tests were α = .72 to .89. IRT analyses (Rasch and partial credit models) yielded good Infit and Outfit measures and high precision for parameter estimation. The potential utility of these memory tasks for psychological research and practice will be discussed.

The irrelevant sound effect under articulatory suppression is a suffix effect even with five-item lists

The relationship between the suffix effect and the effect of irrelevant sound on serial recall of auditorily presented lists is investigated in this study. Contrary to the predictions of the phonological loop model, Hanley and Hayes (2012) reported that the irrelevant sound effect was abolished under articulatory suppression when a spoken suffix was added at the end of the list. The experiment reported in this paper uses a shorter list length (five items per list) than that employed by Hanley and Hayes. This is because it cannot realistically be argued that participants will abandon the use of phonological codes to retain the list items with sequences as short as this. Results replicated those of Hanley and Hayes (2012). There was a significant effect of irrelevant sound under articulatory suppression when the list items were followed by an auditory tone. Crucially, however, the effect of irrelevant sound under articulatory suppression was abolished when the list items were followed by a spoken suffix.

New considerations for the cognitive locus of impairment in the irrelevant-sound effect

The finding that serial recall performance for visually presented items is impaired by concurrently presented task-irrelevant speech or sounds is referred to as the irrelevant-speech/-sound effect (ISE). Substantial evidence has indicated that the impairment of serial rehearsal can result in an ISE, and this may be explained by several models. The present series of experiments has demonstrated an ISE in surprise nonserial recognition tasks in which participants were unaware of the need to maintain a large number of visual items for a later memory test, suggesting that neither the rehearsal nor maintenance of order information is necessary for observing the ISE. This effect was observed for both steady-state and changing-state irrelevant sounds, suggesting that the present results do not derive from a confusion of order information, but instead provide evidence that identity representations can also be impaired by irrelevant sound.

Does the modality effect exist? And if so, which modality effect?

The modality effect is a central issue in multimedia learning [see Mayer (Cambridge University Press, 2005a), for a review]. Sweller's Cognitive Load Theory (CLT), for example, presumes that an illustrated text is better understood when presented visually rather than orally. The predictive power of CLT lies in how it links in to Baddeley's (1986) model of working memory and Penney's (Mem Cognit 17:398-442, 1989) Separate-Streams Hypothesis. Ginns's (Learn Instr 4:313-331, 2005) recent meta-analysis also supports the modality effect (d = 0.72, based on 43 independent effects). This article replicates the meta-analysis of the modality effect based on 86 independent effects (with within-study subgroups as the unit of analysis and with mean of the outcomes as the dependent measure), with results showing a reduction of the overall effect size by almost half (d = 0.38), and even more when Duval and Tweedie's Trim and Fill method is used to correct publication bias (d = 0.20). This article also widens the scope of the analysis of moderator variables (e.g. Pace of presentation, Type of visualization, Research group) as well as their potentially confounded effects. Finally, it is argued that, for theoretical reasons, the so-called modality effect cannot be based on Penney's or Baddeley's theories and must be explained in a different way.

Gummed-up memory: chewing gum impairs short-term recall

Several studies have suggested that short-term memory is generally improved by chewing gum. However, we report the first studies to show that chewing gum impairs short-term memory for both item order and item identity. Experiment 1 showed that chewing gum reduces serial recall of letter lists. Experiment 2 indicated that chewing does not simply disrupt vocal-articulatory planning required for order retention: Chewing equally impairs a matched task that required retention of list item identity. Experiment 3 demonstrated that manual tapping produces a similar pattern of impairment to that of chewing gum. These results clearly qualify the assertion that chewing gum improves short-term memory. They also pose a problem for short-term memory theories asserting that forgetting is based on domain-specific interference given that chewing does not interfere with verbal memory any more than tapping. It is suggested that tapping and chewing reduce the general capacity to process sequences.

Relations between timing, position, and grouping in short-term memory

This article is concerned with how information about time and position in a sequence is represented in short-term memory and expressed in the dynamics of serial recall. Temporal-distinctiveness theories of memory predict that isolating a list item in time will improve recall accuracy for that item. Although the majority of research in short-term memory has failed to demonstrate a temporal isolation effect (TIE), there are occasions on which a TIE is observed. The disparity in results has been explained by assuming that participants can adaptively weight temporal and nontemporal information at retrieval, with differences between experiments promoting or discouraging reliance on time as a source of episodic information. A particular focus of the present study is the finding that the TIE is substantially observed in standard serial recall only when participants are instructed to group the list into minisequences. The findings of two experiments using instructed grouping replicated this effect but showed that it is attributable to a longer gap at the group boundary enhancing the positive effect of grouping on recall accuracy. These results show that the hierarchical representations usually associated with temporal grouping are also elicited by instructed grouping but that an additional and nonspecific benefit to recall obtains from lengthening the pause between groups. An additional role for time is identified in the timing of responses: The dynamics of input sequences tend to be mirrored in output sequences for ungrouped lists, whereas the primacy pattern in grouped lists is for a longer duration to speed access to the following group when that duration occurs at an instructed group boundary.

Evaluating models of working memory through the effects of concurrent irrelevant information

Working memory is believed to play a central role in almost all domains of higher cognition, yet the specific mechanisms involved in working memory are still fiercely debated. We describe a neuroimaging experiment with functional magnetic resonance imaging (fMRI) and a companion behavioral experiment, and in both we seek to adjudicate between alternative theoretical models of working memory on the basis of the effects of interference from articulatory suppression, irrelevant speech, and irrelevant nonspeech. In Experiment 1 we examined fMRI signal changes induced by each type of irrelevant information while subjects performed a probed recall task. Within a principally frontal and left-lateralized network of brain regions, articulatory suppression caused an increase in activity during item presentation, whereas both irrelevant speech and nonspeech caused relative activity reductions during the subsequent delay interval. In Experiment 2, the specific timing of interference was manipulated in a delayed serial recall task. Articulatory suppression was found to be most consequential when it coincided with item presentation, whereas both irrelevant speech and irrelevant nonspeech effects were strongest when limited to the subsequent delay period. Taken together, these experiments provide convergent evidence for a dissociation of articulatory suppression from the 2 irrelevant sound conditions. Implications of these findings are considered for 4 prominent theories of working memory.