Item identification time and rehearsal rate as predictors of memory span in children

According to the working memory model of Baddeley and Hitch (1974), the sensitivity of memory span to word length arises from the time taken to rehearse items in a speech-based “articulatory loop”. Alternatively, it has been suggested that the word-length effect may result from differences in the speed of perceptual processes of item identification. Changes in the speed of rehearsal and of item identification have also been claimed to contribute to the growth of memory span that is seen in development. In order to compare these two variables directly, groups of children aged 8 and 11 were assessed on memory span for words of one, two, and three syllables; span under articulatory suppression; rehearsal rate; and item identification time. Span was found to be a linear function of rehearsal rate across differences in both word length and age. The word-length effect was unrelated to item identification time and was diminished by articulatory suppression. These results show that the word-length effect reflects rehearsal and not item identification processes. However, the results also suggest that changes in item identification time contribute to developmental differences in span when articulation is suppressed. A distinction between item identification and rehearsal effects can be readily interpreted in terms of the working memory model if it is assumed that they indicate the efficiency of different subsystems involved in span.     

List composition and the word length effect in immediate recall: A comparison of localist and globalist assumptions

Lists of short words usually are recalled better than lists of longer words in immediate recall tasks. Such word length effects might be explained by localist accounts, in which the length of each word in a list affects the recall of that word only, or by globalist accounts, in which the lengths of at least some words affect the recall of other words (e.g., Baddeley, 1986). In a recent localist account, Neath and Nairne (1995) proposed that the recall of each word depends on the likelihood that features within the word are contaminated within the memory representation. We tested this by presenting not only homogeneous lists of short and long words, but also mixed lists, and by including articulatory suppression on some trials. The short-word advantage depended on the composition of the list, ruling out a strictly localist approach. There appear to be several globalist influences on recall, including distinctiveness factors as well as phonological storage and articulation.     

The Word-length Effect and Disyllabic Words

Three experiments compared immediate serial recall of disyllabic words that differed on spoken duration. Two sets of long- and short-duration words were selected, in each case maximizing duration differences but matching for frequency, familiarity, phonological similarity, and number of phonemes, and controlling for semantic associations. Serial recall measures were obtained using auditory and visual presentation and spoken and picture-pointing recall. In Experiments 1a and 1b, using the first set of items, long words were better recalled than short words. In Experiments 2a and 2b, using the second set of items, no difference was found between long and short disyllabic words. Experiment 3 confirmed the large advantage for short-duration words in the word set originally selected by Baddeley, Thomson, and Buchanan (1975). These findings suggest that there is no reliable advantage for short-duration disyllables in span tasks, and that previous accounts of a word-length effect in disyllables are based on accidental differences between list items. The failure to find an effect of word duration casts doubt on theories that propose that the capacity of memory span is determined by the duration of list items or the decay rate of phonological information in short-term memory.     

Irrelevant speech eliminates the word length effect

Theword length effect refers to the observation that memory is better for short than for long words. Theirrelevant speech effect refers to the finding that memory is better when items are presented against a quiet background than against one with irrelevant speech. According to Baddeley’s (1986, 1994) working memory, these variables should not interact: The word length effect arises from rehearsal by the articulatory control process, whereas irrelevant speech reduces recall through interference in the phonological store. Four experiments demonstrate that, like articulatory suppression, irrelevant speech eliminates the word length effect for both visual and auditory items. These results (1) provide further evidence against the ability of working memory to explain the word length and irrelevant speech effects and (2) confirm a specific prediction of Nairne’s (1990) feature model.     

Does length or neighborhood size cause the word length effect?

Jalbert, Neath, Bireta, and Surprenant (2011) suggested that past demonstrations of the word length effect, the finding that words with fewer syllables are recalled better than words with more syllables, included a confound: The short words had more orthographic neighbors than the long words. The experiments reported here test two predictions that would follow if neighborhood size is a more important factor than word length. In Experiment 1, we found that concurrent articulation removed the effect of neighborhood size, just as it removes the effect of word length. Experiment 2 demonstrated that this pattern is also found with nonwords. For Experiment 3, we factorially manipulated length and neighborhood size, and found only effects of the latter. These results are problematic for any theory of memory that includes decay offset by rehearsal, but they are consistent with accounts that include a redintegrative stage that is susceptible to disruption by noise. The results also confirm the importance of lexical and linguistic factors on memory tasks thought to tap short-term memory.     

Noise effects on rehearsal rate in short term serial order memory

Three experiments are reported which were designed to test the hypothesis that the rate of rehearsal during noise is slower than that under quiet conditions. The first experiment measured directly the rate of articulation while subjects either read or rehearsed a set of five consonants. It was shown that while the rate of articulation when reading aloud did not differ under the two noise levels [65 dB(C) and 85 dB(C)], rate of articulation during overt rehearsal in loud noise was significantly slower than under quiet conditions. In Experiment II a similar effect was demonstrated where words were required to be read or rehearsed; here it was shown that the greatest impairment due to noise was on the rate of rehearsal of words of long spoken length.

The third experiment showed that loud noise impaired recall performance more markedly for a set of words of long spoken length presented early on in the sequence than for a set of shorter words, even though both sets were equal in the number of syllables and phonemes they contained.

It was concluded that in verbal memory tasks where rote rehearsal of the to-be-remembered material is the predominant strategy for enhancing trace duration, noise may affect memory performance by slowing down the rehearsal rate.     

Articulatory suppression and phonological codes in reading for meaning

The aim of this study was to investigate whether the phonological code that causes errors in printed sentence comprehension is affected by concurrent articulation. Forty adult subjects made speeded judgements of the acceptability of printed sentences. The critical sentences were foils that were (1) orthographi-cally unacceptable but phonologically acceptable (e.g. The palace had a thrown room), and (2) spelling controls that were orthographically and phonologically unacceptable (The palace had a thorns room). Half the subjects performed this task in silence (without concurrently articulating) and showed a marked phonological effect such that false alarms to phonologically acceptable foils were more frequent than false alarms to their spelling controls. The remaining subjects who performed this task with concurrent articulatory suppression showed an increase in false alarm rates, but no effect of phonology. In a control experiment using the same subjects, memory span for visually presented long and short words was measured under conditions of silence or concurrent articulation. The word length effect (Baddeley, Thomson, & Buchanan, 1975) disappeared under suppression, indicating that the suppression manipulation was highly effective. Thus the phonological codes that are used both in sentence comprehension and memory span are highly susceptible to articulatory suppression. We discuss possible relationships between phonological codes that mediate lexical access and those that support short-term verbal memory.     

Unimpaired short-term memory and rhyme judgement in congenitally speechless individuals: Implications for the notion of “articulatory coding”

In normal adults, concurrent articulation impairs short-term memory, abolishing both the phonological similarity effect and the word length effect when visual presentation is used. It also interferes with ability to judge whether visually presented words rhyme. It is generally assumed that concurrent articulation impairs performance because it prevents people from recoding material into an articulatory form. If this is the explanation, then individuals who are congenitally speechless (anarthric) or speech-impaired (dysarthric) should show the same impairments as normal individuals who are concurrently articulating—i.e. they should have reduced memory spans, fail to show word length and phonological similarity effects in short-term memory, and find rhyme judgement difficult. These predictions were tested in a study of 48 cerebral palsied individuals: 12 anarthric, 12 dysarthric, and 24 controls individually matched to the speech-impaired subjects. There was no impairment of memory span in speech-impaired subjects, who showed normal phonological similarity and word-length effects in short-term memory. Speech-impaired subjects did not differ from their controls in ability to tell whether names of pairs of pictures rhymed. These results challenge the notion that “articulatory coding” is implicated in short-term memory and rhyme judgement and suggests that processes such as rehearsal and phonemic segmentation involve generation of a more abstract central phonological code.     

Is there a temporal basis of the word length effect? A response to Service (1998)

Service (1998) carried out a study of the word length effect with Finnish pseudowords in which short and long pseudowords were identical except for the inclusion of certain phonemes differing only in pronunciation length, a manipulation that is impossible in English. She obtained an effect of phonemic complexity but little or no word duration effect per se - a discrepancy from the expectations generated by the well-known working memory model of Baddeley (1986). In the present study using English words, we controlled for phonemic complexity differences by using the same words for the short- and long-word sets, but with instructions inducing shorter or longer pronunciation of the words. We obtained substantial word duration effects. Concerns raised by Service are addressed, and we conclude that both duration and complexity are likely to contribute to the word length effect in serial recall.     

The Effect of Word Length on Immediate Serial Recall Depends on Phonological Complexity, Not Articulatory Duration

Immediate recall for sequences of short words is better than for sequences of long words. This word-length effect has been thought to depend on the spoken duration of the words (Baddeley, Thomson, & Buchanan, 1975) or their phonological complexity (Caplan, Rochon, & Waters, 1992). In Finnish both vowel and consonant quantity distinguish between words. Long phonemes behave like phoneme repetitions. In Experiment 1, subjects were presented with auditory lists of three kinds of pseudowords based on Finnish phonotactics: short CVCV-structures (e.g. / tepa/ ), long two-syllable items with long phonemes (e.g. / te: p: a / ), and long three-syllable items with CVCVCV structures (e.g. / tepalo / ). Although both kinds of long stimuli (of identical spoken length) took longer to read, only three-syllable items were more difficult to remember than the short stimuli. Experiment 2 contrasted the effect of number of syllables with number of different phonemes. The long two-syllable items were replaced by two-syllable items of equal spoken duration but containing six different phonemes (e.g. / tiempa / ). These two-syllable items were as difficult to recall as were the three-syllable items. Experiment 3 controlled for the possibility that long stimuli might be rehearsed in a shorter form. It is concluded that aspects of phonological complexity are critical for word-length effects. Implications of this finding for working memory theory are discussed, and future work based on multi-layered phonological representations is proposed.     

Is scanning in probed order recall articulatory?

We consider how theories of serial recall might apply to other short-term memory tasks involving recall of order. In particular, we consider the possibility that when participants are cued to recall an item at an arbitrary position in a sequence, they covertly serially recall the list up to the cued position. One question is whether such “scanning” is articulatory in nature. Two experiments are presented in which the syllabic length of words preceding and following target positions were manipulated, to test the prediction of an articulatory-based mechanism that time to recall an item at a particular position will depend on the number of preceding long words. Although latency was dependent on target position, no word length effects on latency were observed. Additionally, the effects of word length on accuracy replicate recent demonstrations in serial recall that recall accuracy is dependent on the word length of all list items, not just that of target items, in line with distinctiveness assumptions. It is concluded that if scanning does occur, it is not carried out by covert or overt articulation.     

Word-length effects in immediate memory: Overwriting trace decay theory

Memory is worse for items that take longer to pronounce, even when the items are equated for frequency, number of syllables, and number of phonemes. Current explanations of the word-length effect rely on a time-based decay process within the articulatory loop structure in working memory. Using an extension of Nairne’s (1990) feature model, we demonstrate that the approximately linear relationship between span and pronunciation rate can be observed in a model that does not use the concept of decay. Moreover, the feature model also correctly predicts the effects of modality, phonological similarity, articulatory suppression, and serial position on memory for items of different lengths. We argue that word-length effects do not offer sufficient justification for including time-based decay components in theories of memory.     

工作记忆中汉语反词长效应机制

工作记忆中的反词长效应(reverse word-length effect)指在对长词和短词混合的词表进行即时序列回忆时, 独立长词回忆成绩优于独立短词的现象。以汉字词语为材料通过3个实验探讨反词长效应的机制。实验1采用纯粹词表和长短词混合词表, 既得到纯粹词词长效应, 也得到独立词反词长效应。实验2削弱了长短词之间的词长差异, 结果独立词反词长效应消失, 且独立词回忆成绩优于纯粹词。实验3设计了视觉延迟条件, 得到与实验1类似的结果, 只是独立词反词长效应有所削弱。三个实验的结果并不一致, 无法用现有的语音回路理论或SIMPLE理论进行很好地解释, 理论的整合与创新显得非常重要。因此, 提出多重编码以既相互竞争又相互补充方式进行平行加工的观点进行更完整地解释。     

Presentation format and its effect on working memory

In three experiments, we examined the separate cognitive demands of processing and storage in working memory and looked at how effective the coordination was when items for storage varied in format/modality. A sentence verification task involving arithmetic facts was combined with a span task involving two to six items presented in picture, printed word, or spoken word format. The first two experiments were the same, except for the added requirement of articulation of the math sentence in Experiment 2. Experiment 3 varied the length of the span item and compared recall with recognition performance. The results showed that both spoken words and picture produced superior recall and recognition, as compared with printed words, and are consistent with Baddeley and Logie's (1999) and Mayer's (2001) models of working memory. Also, the differences in processing performance across spans varied with the difficulty of the task but showed the strongest support for the resource allocation model (Foos 1995).     

Retroactive interference in short-term memory and the word-length effect

Two experiments investigated the possibility that the word-length effect in short-term memory (STM) is a consequence of long words generating a greater level of retroactive interference than shorter words. In Experiment 1, six-word lists were auditorily presented under articulatory suppression for immediate serial reconstruction of only the first three words. These three words were always drawn from a single set of middle-length words, whereas the last three positions were occupied by either short or long interfering words. The results showed worse memory performance when the to-be-remembered words were followed by long words. In Experiment 2, a recent-probes task was used, in which recent negative probes matched a target word in trial n-2. The results showed lower levels of proactive interference when trial n-1 involved long words instead of short words, suggesting that long words displaced previous STM content to a greater extent. By two different experimental approaches, therefore, this study shows that long words produce more retroactive interference than short words, supporting an interference-based account for the word-length effect.     

Memory for Related and Unrelated Words: Further Evidence on the Influence of Semantic Factors in Immediate Serial Recall

A number of recent studies have explored the role of long-term memory factors in memory span tasks. The effects of lexicality, frequency, imageability, and word class have been investigated. The work reported in this paper examined the effect of semantic organization on the recall of short lists of words. Specifically, the influence of semantic category on immediate serial recall and the interaction of this variable with articulatory suppression was investigated in three experiments. Experiment 1 compared immediate serial recall performance when lists comprising items from the same semantic category were used (homogeneous condition) with a situation where lists held items from different semantic categories. Experiment 2 examined the same conditions with and without articulatory suppression during item presentation, and Experiment 3 reproduced these conditions with suppression occurring throughout presentation and recall. Results of all three experiments showed a clear advantage for the homogeneous condition. Experiments 2 and 3 showed that the homogeneous category advantage did not depend on the articulatory loop. Furthermore, error analysis indicated that this effect was mainly attributable to better item information recall for the homogeneous condition. These results are interpreted as reflecting a long-term memory contribution to the recall stage of immediate serial recall tasks.     

Word length and articulatory suppression affect short-term and long-term recall tasks

In six experiments, subjects were required to recall (either serially or freely) lists of short and long words either immediately or after a study-test filled delay ranging from 30 to 60 sec. In three of these experiments, we investigated the effect that articulatory suppression had in modulating the word length effect in both immediate and delayed free recall. The results suggested that the effects of word length and articulatory suppression were comparable in the immediate and delayed recall tasks. The theoretical relevance of these findings is discussed.     

Multiple short‐term storage: A task to evaluate the coordination function of the central executive

The present paper explores one of the multiple aspects of working memory, specifically the coordinating function of the central executive with a complex double‐stimuli task. Performance on this task requires coordinating the short‐term maintenance of verbal as well as visuospatial information in preparation for recall. The task involves the single recall of words, the single recall of locations, or the recall of localized words. The study of the double‐stimuli task involves three classical interference tasks (articulatory suppression, Moar box tracking, and standing balance position) and comparing with simple span tasks (word recall and location recall). Word and location recall in this double‐stimuli task involves observing the classical interference effects: articulatory suppression impairs word recall performance without affecting location recall, whereas in visuospatial interference tasks the reverse is true. A second analysis showed that when performance on the double‐stimuli task (implying the simultaneous maintenance of verbal and visuospatial material at the same time) is compared with performances on short‐term memory tasks (classical word span or location span using the same material), a significant decrease in performance is observed. In a third analysis a score specific to the complex task was computed (corrected score). This score takes into account the recall capacity for both words and locations. This score, directly related to the capacities of coordination implied in the task, is sensitive to most attentional requirements of interference tasks. Contrary to what can be observed on location recall, the standing balance position did not significantly decrease performance. These results are consistent with an interpretation of the working memory according to which coordination of the subsystems is a function of the central executive.     

Beyond the articulatory loop: A semantic contribution to serial order recall of subspan lists

In two experiments, serial order recall of short lists of content and function words under quiet and articulatory suppression conditions was examined in order to assess the hypotheses that (1) semantic attributes of words contribute to short-term-memory performance, and (2) do soindependently of effects attributable to the articulatory loop component. In Experiment 1, content words were better recalled than function words; both word types were equally impaired by suppression. This provides support for the notion that semantic coding makes an independent contribution to span performance. This word-class effect disappeared in Experiment 2, when content and function words were matched for imageability. These data suggest that at least some aspects of meaning contribute to serial order recall performance for short lists, independently of the articulatory loop.     

Does working memory change with age? The interactions of concurrent articulation with the effects of word length and acoustic confusion

ABSTRACT

The effects of acoustic confusion (phonological similarity), word length, and concurrent articulation (articulatory suppression) are cited as support for Working Memory's phonological loop component (e.g., Baddeley, 2000 Baddeley, A. D. 2000. The phonological loop and irrelevant speech effect: Some comments on Neath. Psychonomic Bulletin and Review, 7: 544–549. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar], Psychonomic Bulletin and Review, 7, 544). Research has focused on younger adults, with no studies examining whether concurrent articulation reduces the word length and acoustic confusion effects among older adults. In the current study, younger and older adults were given lists of similar and dissimilar letters (Experiment 1) or long and short words (Experiment 2) for immediate serial reconstruction of order. Items were presented visually or auditorily, with or without concurrent articulation. As expected, younger and older adults demonstrated effects of acoustic confusion, word length, and concurrent articulation. Further, concurrent articulation reduced the effects of acoustic confusion and word length equally for younger and older adults. This suggests that age-related differences occur in overall performance, but do not reflect an age-related deficiency in the functioning of the phonological loop component of working memory.