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 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).

When is forewarned forearmed? Predicting auditory distraction in short-term memory.

Two experiments critically examined a predictive-coding based account of the vulnerability of short-term memory (STM) to auditory distraction, particularly the disruptive effect of changing-state sound on verbal serial recall. Experiment 1 showed that providing participants with the opportunity to predict the contents of an imminent spoken distractor sentence via a forewarning reduced its particularly disruptive effect but only to the same level of disruption as that produced by simpler changing-state sequences (a sequence of letter-names). Moreover, a postcategorically unpredictable changing-state sequence (e.g., "F, B, H, E, . . .") was no more disruptive than a postcategorically predictable sequence ("A, B, C, D, . . ."). Experiment 2 showed that a sentence distractor was disruptive regardless of whether participants reported adopting a serial rehearsal strategy to perform the focal task (in this case, a missing-item task) whereas, critically, the disruptive effect of simpler changing-state sequences was only found in participants who reported using a serial rehearsal strategy. Moreover, when serial rehearsal was not used to perform the focal task, the disruptive effect of sentences was completely abolished by a forewarning. These results indicate that predictability plays no role in the classical changing-state irrelevant sound effect and that foreknowledge selectively attenuates a functionally distinct stimulus-specific attentional-diversion effect. As such, the results are at odds with a unitary, attentional account of auditory distraction in STM and instead strongly support a duplex-mechanism account. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

How the deployment of visual attention modulates auditory distraction.

Classically, attentional selectivity has been conceptualized as a passive by-product of capacity limits on stimulus processing. Here, we examine the role of more active cognitive control processes in attentional selectivity, focusing on how distraction from task-irrelevant sound is modulated by levels of task engagement in a visually presented short-term memory task. Task engagement was varied by manipulating the load involved in the encoding of the (visually presented) to-be-remembered items. Using a list of Navon letters (where a large letter is composed of smaller, different-identity letters), participants were oriented to attend and serially recall the list of large letters (low encoding load) or to attend and serially recall the list of small letters (high encoding load). Attentional capture by a single deviant noise burst within a task-irrelevant tone sequence (the deviation effect) was eliminated under high encoding load (Experiment 1). However, distraction from a continuously changing sequence of tones (the changing-state effect) was immune to the influence of load (Experiment 2). This dissociation in the amenability of the deviation effect and the changing-state effect to cognitive control supports a duplex-mechanism over a unitary-mechanism account of auditory distraction in which the deviation effect is due to attentional capture whereas the changing-state effect reflects direct interference between the processing of the sound and processes involved in the focal task. That the changing-state effect survives high encoding load also goes against an alternative explanation of the attenuation of the deviation effect under high load in terms of the depletion of a limited perceptual resource that would result in diminished auditory processing.

The resilience of verbal sequence learning: Evidence from the Hebb repetition effect.

In a single large-scale study, we demonstrate that verbal sequence learning as studied using the classic Hebb repetition effect (Hebb, 1961)-the improvement in the serial recall of a repeating sequence compared to nonrepeated sequences-is resilient to both wide and irregular spacing between sequence repetitions. Learning of a repeated sequence of letters was evident to a comparable degree with three, five, and eight intervening nonrepeated sequences and regardless of whether the spacing between repetitions was regular or irregular. Importantly, this resilience of verbal sequence learning was observed despite complete item-set overlap between repeated and nonrepeated sequences. The findings are consistent with the conceptualization of the Hebb repetition effect as a laboratory analogue of natural phonological word-form learning. The results also have implications for the two leading models of Hebb sequence learning: Whereas the results are incompatible with the model of Page and Norris (2009), they can be handled readily by the model of Burgess and Hitch (2006) through the abandonment of its assumption of long-term (across-trial level) decay. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Postcategorical auditory distraction in short-term memory: Insights from increased task load and task type.

Task-irrelevant speech impairs short-term serial recall appreciably. On the interference-by-process account, the processing of physical (i.e., precategorical) changes in speech yields order cues that conflict with the serial-ordering process deployed to perform the serial recall task. In this view, the postcategorical properties (e.g., phonology, meaning) of speech play no role. The present study reassessed the implications of recent demonstrations of auditory postcategorical distraction in serial recall that have been taken as support for an alternative, attentional-diversion, account of the irrelevant speech effect. Focusing on the disruptive effect of emotionally valent compared with neutral words on serial recall, we show that the distracter-valence effect is eliminated under conditions-high task-encoding load-thought to shield against attentional diversion whereas the general effect of speech (neutral words compared with quiet) remains unaffected (Experiment 1). Furthermore, the distracter-valence effect generalizes to a task that does not require the processing of serial order-the missing-item task-whereas the effect of speech per se is attenuated in this task (Experiment 2). We conclude that postcategorical auditory distraction phenomena in serial short-term memory (STM) are incidental: they are observable in such a setting but, unlike the acoustically driven irrelevant speech effect, are not integral to it. As such, the findings support a duplex-mechanism account over a unitary view of auditory distraction. (PsycINFO Database Record

Differences in Auditory Distraction between Adults and Children: A Duplex-mechanism Approach.

Differences in the impact of irrelevant sound on recall performance in children (aged 7-9 years old; N = 89) compared to adults (aged 18-22 years old; N = 89) were examined. Tasks that required serial rehearsal (serial and probed-order recall tasks) were contrasted with one that did not (the missing-item task) in the presence of irrelevant sound that was either steady-state (a repeated speech token), changing-state (two alternating speech tokens) and, for the first time with a child sample, could also contain a deviant token (a male-voice token embedded in a sequence otherwise spoken in a female voice). Participants either completed tasks in which the to-be-remembered list-length was adjusted to individual digit span or was fixed at one item greater than the average span we observed for the age-group. The disruptive effects of irrelevant sound did not vary across the two methods of determining list-length. We found that tasks encouraging serial rehearsal were especially affected by changing-state sequences for both age-groups (i.e., the changing-state effect) and there were no group differences in relation to this effect. In contrast, disruption by a deviant sound-generally assumed to be the result of attentional diversion-was evident among children in all three tasks while adults were less susceptible to this effect. This pattern of results suggests that developmental differences in distraction are due to differences in attentional control rather than serial rehearsal efficiency.

Trouble articulating the right words: Evidence for a response-exclusion account of distraction during semantic fluency.

It is widely held that single-word lexical access is a competitive process, a view based largely on the observation that naming a picture is slowed in the presence of a distractor-word. However, problematic for this view is that a low-frequency distractor-word slows the naming of a picture more than does a high-frequency word. This supports an alternative, response-exclusion, account in which a distractor-word interferes because it must be excluded from an articulatory output buffer before the right word can be articulated (the picture name): A high, compared to low, frequency word accesses the buffer more quickly and, as such, can also be excluded more quickly. Here we studied the respective roles of competition and response-exclusion for the first time in the context of semantic verbal fluency, a setting requiring the accessing of, and production of, multiple words from long-term memory in response to a single semantic cue. We show that disruption to semantic fluency by a sequence of to-be-ignored spoken distractors is also greater when those distractors are low in frequency, thereby extending the explanatory compass of the response-exclusion account to a multiple-word production setting and casting further doubt on the lexical-selection-by-competition view. The results can be understood as reflecting the contribution of speech output processes to semantic fluency.

The functional determinants of short-term memory: Evidence from perceptual-motor interference in verbal serial recall.

A functional, perceptual-motor, account of serial short-term memory (STM) is examined by investigating the way in which an irrelevant spoken sequence interferes with verbal serial recall. Even with visual list-presentation, verbal serial recall is particularly susceptible to disruption by irrelevant spoken stimuli that have the same identity as-but that are order-incongruent with-the to-be-remembered items. We test the view that such interference is because of the obligatory perceptual organization of the spoken stimuli yielding a sequence that competes with a subvocal motor-plan assembled to support the reproduction of the to-be-remembered list. In support of this view, the interference can be eliminated without changing either the identities or objective serial order of the spoken stimuli but merely by promoting a subjective perceptual organization that strips them of their order-incongruent relation to the to-be-remembered list (Experiment 1). The interference is also eliminated if subvocal motor sequence-planning is impeded via articulatory suppression (Experiment 2). The results are in line with the view that performance-limits in verbal serial STM are because of having to exploit perceptual and motor processes for purposes for which they did not evolve, not the inherently limited capacity of structures or mechanisms dedicated to storage. (PsycINFO Database Record

Memory as embodiment: The case of modality and serial short-term memory.

Classical explanations for the modality effect-superior short-term serial recall of auditory compared to visual sequences-typically recur to privileged processing of information derived from auditory sources. Here we critically appraise such accounts, and re-evaluate the nature of the canonical empirical phenomena that have motivated them. Three experiments show that the standard account of modality in memory is untenable, since auditory superiority in recency is often accompanied by visual superiority in mid-list serial positions. We explain this simultaneous auditory and visual superiority by reference to the way in which perceptual objects are formed in the two modalities and how those objects are mapped to speech motor forms to support sequence maintenance and reproduction. Specifically, stronger obligatory object formation operating in the standard auditory form of sequence presentation compared to that for visual sequences leads both to enhanced addressability of information at the object boundaries and reduced addressability for that in the interior. Because standard visual presentation does not lead to such object formation, such sequences do not show the boundary advantage observed for auditory presentation, but neither do they suffer loss of addressability associated with object information, thereby affording more ready mapping of that information into a rehearsal cohort to support recall. We show that a range of factors that impede this perceptual-motor mapping eliminate visual superiority while leaving auditory superiority unaffected. We make a general case for viewing short-term memory as an embodied, perceptual-motor process.

Dynamic cognitive control of irrelevant sound: Increased task engagement attenuates semantic auditory distraction.

Two experiments investigated reactive top-down cognitive control of the detrimental influence of spoken distractors semantically related to words presented visually for free recall. Experiment 1 demonstrated that an increase in focal-task engagement-promoted experimentally by reducing the perceptual discriminability of the visual target words-eliminated the disruption by such distractors of veridical recall and also attenuated the erroneous recall of the distractors. A recall instruction that eliminates the requirement for output monitoring was used in Experiment 2 to investigate whether increased task engagement shields against distraction through a change in output-monitoring processes (back-end control) or by affecting the processing of the distractors during their presentation (front-end control). Rates of erroneous distractor recall were much greater than in Experiment 1, but both erroneous distractor recall and the disruptive effect of distractors on veridical recall were still attenuated under reduced target-word discriminability. Taken together, the results show that task engagement is under dynamic strategic control and can be modulated to shield against auditory distraction by attenuating distractor processing at encoding, thereby preventing distractors from coming to mind at test. (PsycINFO Database Record

Erroneous and veridical recall are not two sides of the same coin: Evidence from semantic distraction in free recall.

Two experiments examined the extent to which erroneous recall blocks veridical recall using, as a vehicle for study, the disruptive impact of distractors that are semantically similar to a list of words presented for free recall. Instructing participants to avoid erroneous recall of to-be-ignored spoken distractors attenuated their recall but this did not influence the disruptive effect of those distractors on veridical recall (Experiment 1). Using an externalized output-editing procedure-whereby participants recalled all items that came to mind and identified those that were erroneous-the usual between-sequences semantic similarity effect on erroneous and veridical recall was replicated but the relationship between the rate of erroneous and veridical recall was weak (Experiment 2). The results suggest that forgetting is not due to veridical recall being blocked by similar events.

Auditory attentional capture: implicit and explicit approaches.

The extent to which distracting items capture attention despite being irrelevant to the task at hand can be measured either implicitly or explicitly (e.g., Simons, Trends Cogn Sci 4:147-155, 2000). Implicit approaches include the standard attentional capture paradigm in which distraction is measured in terms of reaction time and/or accuracy costs within a focal task in the presence (vs. absence) of a task-irrelevant distractor. Explicit measures include the inattention paradigm in which people are asked directly about their noticing of an unexpected task-irrelevant item. Although the processes of attentional capture have been studied extensively using both approaches in the visual domain, there is much less research on similar processes as they may operate within audition, and the research that does exist in the auditory domain has tended to focus exclusively on either an explicit or an implicit approach. This paper provides an overview of recent research on auditory attentional capture, integrating the key conclusions that may be drawn from both methodological approaches.

Auditory distraction: A duplex-mechanism account.

A body of laboratory work is reviewed suggesting that auditory distraction comes in two functionally distinct forms. Interference-by-process is produced when the involuntary processing of the sound competes with a similar process applied deliberately to perform a focal task. In contrast, attentional capture is produced when the sound causes a disengagement of attention away from the prevailing task, regardless of the task processes involved. Particular attention is devoted to reviewing a range of converging evidence from both experimental and individual- and group-differences-based research, indicating that auditory attentional capture is controllable via greater top-down task engagement whereas interference-by-process is not.

Cognitive control of auditory distraction: impact of task difficulty, foreknowledge, and working memory capacity supports duplex-mechanism account.

The influence of top-down cognitive control on 2 putatively distinct forms of distraction was investigated. Attentional capture by a task-irrelevant auditory deviation (e.g., a female-spoken token following a sequence of male-spoken tokens)-as indexed by its disruption of a visually presented recall task-was abolished when focal-task engagement was promoted either by increasing the difficulty of encoding the visual to-be-remembered stimuli (by reducing their perceptual discriminability; Experiments 1 and 2) or by providing foreknowledge of an imminent deviation (Experiment 2). In contrast, distraction from continuously changing auditory stimuli ("changing-state effect") was not modulated by task-difficulty or foreknowledge (Experiment 3). We also confirmed that individual differences in working memory capacity--typically associated with maintaining task-engagement in the face of distraction--predict the magnitude of the deviation effect, but not the changing-state effect. This convergence of experimental and psychometric data strongly supports a duplex-mechanism account of auditory distraction: Auditory attentional capture (deviation effect) is open to top-down cognitive control, whereas auditory distraction caused by direct conflict between the sound and focal-task processing (changing-state effect) is relatively immune to such control.

Inhibitory control in memory: evidence for negative priming in free recall.

Cognitive control mechanisms--such as inhibition--decrease the likelihood that goal-directed activity is ceded to irrelevant events. Here, we use the action of auditory distraction to show how retrieval from episodic long-term memory is affected by competitor inhibition. Typically, a sequence of to-be-ignored spoken distracters drawn from the same semantic category as a list of visually presented to-be-recalled items impairs free recall performance. In line with competitor inhibition theory (Anderson, 2003), free recall was worse for items on a probe trial if they were a repeat of distracter items presented during the previous, prime, trial (Experiment 1). This effect was produced only when the distracters were dominant members of the same category as the to-be-recalled items on the prime. For prime trials in which distracters were low-dominant members of the to-be-remembered item category or were unrelated to that category--and hence not strong competitors for retrieval--positive priming was found (Experiments 2 and 3). These results are discussed in terms of inhibitory approaches to negative priming and memory retrieval.

Retrieval from memory: vulnerable or inviolable?

We show that retrieval from semantic memory is vulnerable even to the mere presence of speech. Irrelevant speech impairs semantic fluency--namely, lexical retrieval cued by a semantic category name--but only if it is meaningful (forward speech compared to reversed speech or words compared to nonwords). Moreover, speech related semantically to the retrieval category is more disruptive than unrelated speech. That phonemic fluency--in which participants are cued with the first letter of words they are to report--was not disrupted by the mere presence of meaningful speech, only by speech in a related phonemic category, suggests that distraction is not mediated by executive processing load. The pattern of sensitivity to different properties of sound as a function of the type of retrieval cue is in line with an interference-by-process approach to auditory distraction.

Broken expectations: violation of expectancies, not novelty, captures auditory attention.

The role of memory in behavioral distraction by auditory attentional capture was investigated: We examined whether capture is a product of the novelty of the capturing event (i.e., the absence of a recent memory for the event) or its violation of learned expectancies on the basis of a memory for an event structure. Attentional capture-indicated by disruption of a focal visually presented serial recall task-was found when the voice conveying a concurrent irrelevant auditory sequence changed every 5 recall trials (from male to female or vice versa). There was no evidence of attentional capture when the irrelevant sequence was first encountered and hence novel; capture occurred only when an expectation for a particular voice had been learned and then violated. Furthermore, with the increasing predictability of (and hence expectancy for) the voice changes across the experimental session, the capture response diminished only to be reinstated when that session-wide expectation was itself violated by a break in the change-every-5-trials pattern. The results highlight the critical role of learned expectations, as opposed to novelty detection, in behavioral auditory attentional capture.

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.