Articulatory rehearsal and phonological storage in working memory

The theoretical distinction between an articulatory control process and a short-term phonological store was supported in five experiments on immediate serial recall. In Experiment 1, articulatory suppression during the presentation and recall of auditory material abolished the word length effect but not the phonemic similarity effect. In Experiment 2, the two latter effects were found to be independent with auditory presentation. In Experiment 3, the effects of irrelevant speech and word length were found to be independent with visual presentation. In Experiment 4, articulatory suppression during the presentation and recall of auditory material abolished the phonemic similarity effect with a slow presentation rate. Nevertheless, in Experiment 5, articulatory suppression with a conventional presentation rate did not reduce the effect of phonemic similarity, even when a 10-sec interval was interposed between presentation and recall. These results indicate that the encoding, maintenance, and retrieval of spoken material within the phonological store do not depend on a process of articulatory rehearsal.     

The phonological loop: Some answers and some questions

Jones, Hughes, and Macken (2007) claim that their data and our own are inconsistent with a multicomponent working-memory model. We explain in greater detail how the model can account for the data and can address their more specific criticisms. Both sides accept that data relating to the presence of a phonological similarity effect throughout the list depend on list length. We accept that, at this point, all explanations of their interaction are speculative and require further empirical investigation. We examine J, H, & M's interpretation of their and our results in terms of an auditory modality effect, observing that their interpretation of this effect is not well supported by the literature. We suggest that their account assumes a very narrow basis for a general theory of short-term retention, in contrast to a phonological loop interpretation, which forms part of a well-developed and articulated model of working memory.     

Prospective memory in dynamic environments: effects of load, delay, and phonological rehearsal

A new paradigm was developed to examine prospective memory performance in a visual-spatial task that resembles some aspects of the work of air traffic controllers. Two experiments examined the role of workload (number of aeroplanes that participants directed), delay (between receipt of prospective instructions and execution), and phonological rehearsal. High workload increased prospective memory errors but increasing delay from 1-3 or 5 minutes had no effect. Shadowing aurally presented text reduced prospective memory performance, presumably because it prevented verbal rehearsal of the prospective instructions. However, performance on the foreground task of directing aeroplanes to routine destinations was affected only by workload and not by opportunity for rehearsal. Our results suggest that ability to maintain performance on a routine foreground task while performing a secondary task--perhaps analogous to conversation--does not predict ability to retrieve a prospective intention to deviate from the routine.     

Functioning of the phonological loop in auditory hallucinations

Two experiments designed to assess the functioning of the phonological store and loop were carried out with schizophrenic patients experiencing auditory hallucinations, schizophrenic patients not experiencing hallucinations and normal subjects. In the first experiment, phonological encoding was assessed. Although both groups of psychiatric patients performed more poorly overall than the normal subjects, there were no significant differences between the performances of the hallucinating and nonhallucinating patients. In the second experiment, the unattended speech effect (a phenomenon thought to reflect the functioning of the phonological store in normal subjects) was assessed in hallucinating schizophrenic patients, non-hallucinating schizophrenic patients and normal controls. The psychiatric patients performed more poorly overall than the normal subjects, but there was no evidence of abnormal functioning of the phonological store or loop in either patient group. Overall, the findings indicate that phonological store and loop abnormalities are not implicated in the experience of auditory hallucinations.     

Duration estimation and the phonological loop: Articulatory suppression and irrelevant sounds

Clock-based theories of time estimation propose that clock pulses are accumulated in working memory. Although these theories do not constrain the form of the memory trace, evidence reported in the literature suggests that active manipulation of a verbal trace may be involved. Four experiments are reported in which participants reproduced or verbally estimated short durations (up to a few seconds) either in a single-task condition or in a condition with a phonological load. Experiments 1, 2 and 4 showed that both interval reproduction and verbal estimation were impaired under concurrent articulatory suppression in comparison to a timing only control condition. Neither irrelevant speech (Experiments 1-3) nor irrelevant tones and music (Experiment 3) impaired timing performance. These findings are taken to show that time estimation is mediated by phonological working memory and the involvement of an active articulatory rehearsal process.     

Irrelevant speech,articulatory suppression,and phonological similarity: A test of the phonological loop model and the feature model

Two experiments tested competing predictions about the nature of the irrelevant speech effect that were derived from Neath's (2000) feature model and from Salamé and Baddeley's (1982) phonological loop model. The first experiment examined the combined effects of irrelevant speech and articulatory suppression when target items were presented auditorily. Contrary to the suggestions of Neath, but consistent with the phonological loop model, the effects of articulatory suppression and irrelevant speech were additive even when the irrelevant speech was presented during the retention interval The second experiment examined the combined effects of irrelevant speech and phonological similarity when target items were presented visually. Consistent with the phonological loop model, the effects of phonological similarity and irrelevant speech were additive when participants were specifically instructed to use articulatory/phonological rehearsal to remember the list items. The results therefore contradicted Neath's claim that irrelevant speech abolishes the phonological similarity effect when list items are presented visually. However, the effect of phonological similarity was abolished in the irrelevant speech conditions when no instructions were given concerning rehearsal. It is argued that the phonological similarity effect disappears in some experiments because participants sometimes employ a semantic rehearsal strategy, consistent with the views of Salamé and Baddeley (1986).     

Atypical neural functions underlying phonological processing and silent rehearsal in children who stutter

Phonological processing was examined in school-age children who stutter (CWS) by assessing their performance and recording event-related brain potentials (ERPs) in a visual rhyming task. CWS had lower accuracy on rhyming judgments, but the cognitive processes that mediate the comparisons of the phonological representations of words, as indexed by the rhyming effect (RE) ERP, were similar for the stuttering and normally fluent groups. Thus the lower behavioral accuracy of rhyming judgments by the CWS could not be attributed to that particular stage of processing. Instead, the neural functions for processes preceding the RE, indexed by the N400 and CNV elicited by the primes and the N400 elicited by the targets, suggest atypical processing that may have resulted in less efficient, less accurate rhyming judgment for the CWS. Based on the present results, it seems likely that the neural processes related to phonological rehearsal and target word anticipation, as indexed by the CNV, are distinctive for CWS at this age. Further, it is likely that the relative contributions of the left and right hemispheres differ in CWS in the stage of processing when linguistic integration occurs, as indexed by the N400. Taken together, these results suggest that CWS may be less able to form and retain a stable neural representation of the prime onset and rime as they anticipate the target presentation, which may lead to lower rhyming judgment accuracy.     

The phonological loop model of working memory: An ERP study of irrelevant speech and phonological similarity effects

The phonological loop model for retention of auditory verbal material in working memory, developed by Baddeley, assumes that irrelevant speech and phonological similarity influence only one and the same element of the system—that is, the phonological short-term store. We tested this idea by recording eventrelated potentials (ERPs) to auditorily presented letters that were phonologically similar or dissimilar and were to be memorized in the presence of more or less disturbing irrelevant speech. Irrelevant speech and phonological similarity caused ERP effects with clearly different scalp topographies, indicating that these factors influence different brain systems and hence probably different cognitive elements. Moreover, ERPs indicated that the phonological similarity effect might involve processes at the level of phonological analysis. Our data also support recent suggestions that the irrelevant speech effect is not based on the phonological similarity between relevant and irrelevant material, but on the phonological variability within the irrelevant stream.     

The phonological loop and memory for rhythms: an individual differences approach

The purpose of the current study was to examine the relationship between short-term memory for rhythm and the phonological loop in working memory. Results showed that digit span scores significantly correlated with the scores on the rhythmic memory task, and that the correlation between the two scores remained significant even after the common variance with reading speed was partialled out. Partial correlation and regression analyses indicated that the relation between memory for rhythm and digit span scores is mediated by the third component in the phonological loop, the component that is responsible for regulation of timing mechanisms in immediate memory tasks.     

The phonological loop in task alternation and task repetition

It has recently been proposed that task repetition is easier than task alternation because the appropriate task settings are already present in working memory, whereas during task alternation task settings must be retrieved from long-term memory (Mayr & Kliegl, 2000). The present study tested whether the phonological loop is involved in keeping the relevant task settings active in working memory. It may then be expected that concurrent articulatory suppression would diminish the facilitation associated with task repetition because the phonological loop could no longer maintain the appropriate task settings active in working memory. Both during task repetition and task alternation the relevant task settings should then be retrieved from long-term memory. Three dual-task experiments were conducted. The results of Experiment 1 were in support of our prediction. Experiment 2 replicated the findings of Experiment 1 and showed that the task settings probably represent the adequate response mappings. Experiment 3 ruled out the involvement of the visuo-spatial sketchpad and more general coordination demands during dual tasking.     

The phonological loop in task alternation and task repetition

It has recently been proposed that task repetition is easier than task alternation because the appropriate task settings are already present in working memory, whereas during task alternation task settings must be retrieved from long-term memory (Mayr & Kliegl, 2000). The present study tested whether the phonological loop is involved in keeping the relevant task settings active in working memory. It may then be expected that concurrent articulatory suppression would diminish the facilitation associated with task repetition because the phonological loop could no longer maintain the appropriate task settings active in working memory. Both during task repetition and task alternation the relevant task settings should then be retrieved from long-term memory. Three dual-task experiments were conducted. The results of Experiment 1 were in support of our prediction. Experiment 2 replicated the findings of Experiment 1 and showed that the task settings probably represent the adequate response mappings. Experiment 3 ruled out the involvement of the visuo-spatial sketchpad and more general coordination demands during dual tasking.     

Lexical activation during the recognition of Chinese characters: Evidence against early phonological activation

In two primed-naming experiments involving Chinese character recognition, one with native Mandarinspeaking subjects and another with native Cantonese-speaking subjects, we varied both the stimulus onset asynchrony (SOA) and the prime—target similarity along various lexical dimensions. Across both experiments, the results were as follows: (1) Relatively strong and reliable semantic priming appeared very early across various SOAs, and its onset was not affected by meaning precision, (2) either homophonic priming had negligible effects on target naming or the effects appeared relatively late (only at 57 msec), and (3) graphic inhibition was found across different SOAs. Since the same set of stimuli and procedure were adopted as those in the study of Perfetti and Tan (1998), the present findings raise questions about the reliability and validity of the results from their study that have been used to support the notion that phonology is a constitutive element of character recognition and precedes meaning access in the identification process. Instead, the present results suggest that phonology is optional for accessing meaning in Chinese character recognition among skilled adult readers.     

Impaired activation of the phonological lexicon: effects upon oral reading

The role of the phonological lexicon in oral reading is examined in a patient with a small focal left hemisphere lesion. Impaired access to the patient's phonological lexicon is suggested by a number of findings, including the production of phonemic errors across a variety of tasks; increasing difficulty in word production with increasing word length; and difficulty on tests of homophone and rhyme judgments. Two competing models of reading are tested: the nonlexical ("rules") and the lexical ("no-rules") models. The rules model predicts that a disturbance in the phonological lexicon will result in surface alexia; the no-rules model predicts phonological alexia. Results indicate that the patient's reading is most similar to phonological alexia, providing support for the no-rules model. The applicability of the no-rules model to other forms of acquired alexia is explored.     

Breaking a habit: A further role of the phonological loop in action control

Recent research has suggested that keeping track of a task goal in rapid task switching may depend on the phonological loop component of working memory. In this study, we investigated whether the phonological loop plays a similar role when a single switch extending over several trials is required after many trials on which one has performed a competing task. Participants were shown pairs of digits varying in numerical and physical size, and they were required to decide which digit was numerically or physically larger. An experimental cycle consisted of four blocks of 24 trials. In Experiment 1, participants in the task change groups performed the numerical-size judgment task during the first three blocks, and then changed to the physical-size judgment task in the fourth. Participants in the continuation groups performed only the physical-size judgment task throughout all four blocks. We found negative effects of articulatory suppression on the fourth block, but only in the task change groups. Experiment 2 was a replication, with the modification that both groups received identical instructions and practice. Experiment 3 was a further replication using numerical-size judgment as the target task. The results showed a pattern similar to that from Experiment 1, with negative effects of articulatory suppression found only in the task change group. The congruity of numerical and physical size had a reliable effect on performance in all three experiments, but unlike the task change, it did not reliably interact with articulatory suppression. The results suggest that in addition to its well-established role in rapid task switching, the phonological loop also contributes to active goal maintenance in longer-term action control.     

A strict test of the phonological loop hypothesis with Libyan data

In Arabic, there are two ways, differing in length, of pronouncing each digit. This feature of word pairs that are conceptually identical but of different length allows for a stricter test of the phonological loop hypothesis than has been reported previously. Libyan schoolchildren, both boys and girls, of two grades took part in a quasi-experimental study in which shorter and longer digits and shorter and longer words were presented in recall and pronunciation tasks. The results confirmed the validity of the phonological loop model in that memory span was longer for shorter stimuli. Analysis of the data with structural equation modeling showed that only 17% of the individual-level variation in memory span could be explained by pronunciation speed. In an analysis of covariance, it was determined that pronunciation speed could account for a substantial proportion of the variation found across age (8-year-olds vs. 10-year-olds), stimulus modality (digits vs. words), and stimulus length (short vs. long), but not for gender differences.     

The development of memory maintenance: Children’s use of phonological rehearsal and attentional refreshment in working memory tasks

Past research suggests that children begin to phonologically rehearse at around 7 years of age. Less is known regarding the development of refreshment, an attention-based maintenance mechanism. Therefore, the use of these two maintenance methods by 6- and 8-year-olds was assessed using memory span tasks that varied in their opportunities for maintenance activity. Experiment 1 showed that nonverbal processing impaired both groups’ performance to similar extents. Experiment 2 employed phonologically similar or dissimilar memory items and compared the effects of verbal versus nonverbal processing on recall. Both groups showed evidence of phonological maintenance under nonverbal processing but not under verbal processing. Furthermore, nonverbal processing again impaired recall. Verbal processing was also more detrimental to performance in 8-year-olds than in 6-year-olds. Together, the results suggest that nonverbal processing impairs recall by obstructing refreshment and that developmental change in maintenance between 6 and 8 years of age consists primarily of an increase in phonological rehearsal.     

The phonological loop and the irrelevant speech effect: Some comments on Neath (2000)

Neath (2000) presents a useful overview of the evidence to be explained by any model of the effects of irrelevant speech on immediate serial memory and proposes a model accompanied by computational simulation. While his review is in general accurate, it is limited in its explanation of the crucial characteristics of the disrupting sounds. It also neglects strategic issues, particularly the tendency for subjects to switch strategy as list length increases. As a result, his model fails to account for the absence of an interaction between irrelevant speech and acoustic similarity for lists of span length. Points of issue between Neath’s feature hypothesis and the phonological loop interpretation are outlined, and the contribution of his computational simulation is discussed.     

Orthographic and phonological activation in recognizing Chinese characters

This paper is a contribution to the study of whether visual contact with lexical units in any writing system necessarily arouses their corresponding phonological information. In two experiments it was investigated whether phonological information is automatically activated during the semantic processing of Chinese characters. In these experiments, both using a semantic-categorization task, subjects produced the same proportion of false positive categorization errors and showed the same decision latencies on homophone foils and their non-homophonic controls, thus indicating that phonological information does not seem to affect the semantic task. Experiment 2 further revealed that subjects made more errors and produced longer response times on graphemically similar foils than on the corresponding controls. The absence of phonological effects and the presence of clear effects of visual similarity for Chinese characters in semantic tasks can be taken to indicate that phonological information may not be automatically activated during the processing of meanings of Chinese characters. The present results also cast serious doubts on the hypothesis that phonological activation is a universal principle of lexical processing.     

The time course of orthographic and phonological code activation

The present study used event-related potentials (ERPs) to examine the time course of orthographic and phonological priming in the masked priming paradigm. Participants monitored visual target words for occasional animal names, and ERPs to nonanimal critical items were recorded. These critical items were preceded by different types of primes: Orthographic priming was examined using transposed-letter (TL) primes (e.g., barin-BRAIN) and their controls (e.g., bosin-BRAIN); phonological priming was examined using pseudohomophone primes (e.g., brane-BRAIN) and their controls (e.g., brant-BRAIN). Both manipulations modulated the N250 ERP component, which is hypothesized to reflect sublexical processing during visual word recognition. Orthographic (TL) priming and phonological (pseudohomophone) priming were found to have distinct topographical distributions and different timing, with orthographic effects arising earlier than phonological effects.     

Semantic and phonological activation in noun and pronoun production

Speakers can refer to objects and other entities by nouns or pronouns. The present article investigated the production of gender-marked pronouns in German. Four picture-word interference experiments are reported, addressing 2 questions. First, is the lemma of a referent noun (i.e., the representation of the referent noun's semantic and syntactic properties) accessed when producing a pronoun? Second, if so, is this access confined to the lemma, or will the referent noun's phonological form be activated, too? The results suggest that in generating pronouns, speakers accessed the lemma of the referent noun, whereas its phonological form was not substantially activated. The results are discussed in the context of other recent experimental studies of pronoun and noun production.