The effect of word length in short-term memory: Is rehearsal necessary?

Three experiments investigated the effect of word length on a serial recognition task when rehearsal was prevented by a high presentation rate with no delay between study and test lists. Results showed that lists of short four-phoneme words were better recognized than lists of long six-phoneme words. Moreover, this effect was equivalent to that observed in conditions in which there was a delay between lists, thereby making rehearsal possible in the interval. These findings imply that rehearsal does not play a central role in the origin of the word length effect. An alternative explanation based on differences in the degree of retroactive interference generated by long and short words is proposed.     

The irrelevant sound effect in short-term memory: Is there developmental change?

With two experiments, effects of irrelevant speech and classroom noise on serial recall of common nouns presented pictorially were investigated in children and adults. Experiment 1 used fixed list lengths for children (first graders) and adults. Experiment 2 used list lengths adjusted to participants' (second–third graders, adults) individual spans. In both experiments, children and adults were equally impaired by irrelevant speech. This contrasts with a related study (differences in methodology) by Elliott (2002), who reported severe increase in the detrimental impact of irrelevant speech with decreasing age. In both experiments, classroom noise had no effect in overall analyses. For Experiment 1, however, separate group analyses revealed impairment in children. Results suggest that effects of irrelevant sounds on serial recall stem from two separate mechanisms: Specific interference due to the sounds' automatic access to short-term memory, and/or attention capture. Only for the latter there is developmental change.     

Is the attentional blink effect located in short-term memory?

The attentional blink (AB) effect is characterized by a failure to detect a second target following the identification of a previous target in a RSVP stream. This effect has been attributed to capacity limitations at a central level of visual information processes. Postperceptual models suppose that the AB locus is located in short-term memory. To test this hypothesis, we investigated the influence of a short-term memory deficit on the AB effect in a patient with such a deficit. The three main results of this study are (1) the persistence of an AB effect, (2) a large number of T1 missed identifications and (3) a T2 detection deficit for a specific delay (367 ms). These results indicate that a short-term memory deficit disrupts the processing of each target (T1 and T2) but does not product an abolition of the AB effect.     

Is spoken duration a sufficient explanation of the word length effect?

The word length effect is one of the cornerstones of trace decay plus rehearsal models (TDR) of memory. Words of long spoken duration take longer to rehearse than words of short spoken duration and as such suffer more decay and are thus less well recalled. The current experiment manipulates both syllable length and spoken duration within words of fixed syllable length in an aim to test the assumptions of the TDR model. Our procedures produced robust effects of both syllable length and spoken duration in four measures of the time it takes to pronounce the different types of words. Serial recall for the same materials produced robust syllable effects, but no duration effects.     

The impact of path crossing on visuo-spatial serial memory: Encoding or rehearsal effect?

The determinants of visuo-spatial serial memory have been the object of little research, despite early evidence that not all sequences are equally remembered. Recently, empirical evidence was reported indicating that the complexity of the path formed by the to-be-remembered locations impacted on recall performance, defined for example by the presence of crossings in the path formed by successive locations (Parmentier, Elford, & Maybery, 2005). In this study, we examined whether this effect reflects rehearsal or encoding processes. We examined the effect of a retention interval and spatial interference on the ordered recall of spatial sequences with and without path crossings. Path crossings decreased recall performance, as did a retention interval. In line with the encoding hypothesis, but in contrast with the rehearsal hypothesis, the effect of crossing was not affected by the retention interval nor by tapping. The possible nature of the impact of path crossing on encoding mechanisms is discussed.     

The impact of path crossing on visuo-spatial serial memory: encoding or rehearsal effect?

The determinants of visuo-spatial serial memory have been the object of little research, despite early evidence that not all sequences are equally remembered. Recently, empirical evidence was reported indicating that the complexity of the path formed by the to-be-remembered locations impacted on recall performance, defined for example by the presence of crossings in the path formed by successive locations (Parmentier, Elford, & Maybery, 2005). In this study, we examined whether this effect reflects rehearsal or encoding processes. We examined the effect of a retention interval and spatial interference on the ordered recall of spatial sequences with and without path crossings. Path crossings decreased recall performance, as did a retention interval. In line with the encoding hypothesis, but in contrast with the rehearsal hypothesis, the effect of crossing was not affected by the retention interval nor by tapping. The possible nature of the impact of path crossing on encoding mechanisms is discussed.     

Is spoken duration a sufficient explanation of the word length effect?

The word length effect is one of the cornerstones of trace decay plus rehearsal models (TDR) of memory. Words of long spoken duration take longer to rehearse than words of short spoken duration and as such suffer more decay and are thus less well recalled. The current experiment manipulates both syllable length and spoken duration within words of fixed syllable length in an aim to test the assumptions of the TDR model. Our procedures produced robust effects of both syllable length and spoken duration in four measures of the time it takes to pronounce the different types of words. Serial recall for the same materials produced robust syllable effects, but no duration effects.     

Free recall measures of short-term store: Are rehearsal and order of recall data necessary?

Several investigators have claimed that immediate free recall is a composite of output from two different storage systems—a short-term store (STS) and a long-term store (LTS). Free recall data and measures of STS were evaluated by having subjects report their rehearsals while lists of words were presented at a rate of one word every 1.25, 2.50, or 5.00 sec. The results support the conclusions that (a) arranging recall as a function of where an item was presented, rather than where it was rehearsed, is inappropriate to discussions of STS and LTS, and (b) computing measures of STS without both rehearsal and order of recall data yields a biased estimate of STS.

     

Characteristics of spatial memory span: Is there an analogy to the word length effect, based on movement time?

In studies of verbal short-term memory it has been shown that the length of words to be remembered affects the size of memory span. This word-length effect is attributed to relationships between the rate of rehearsal of verbal material and the time it takes to speak the words being rehearsed. For spatial memory span there may also be an internal rehearsal system linked to overt responding, and if there is a strong analogy to be drawn between the verbal and spatial domains then movement time between spatial targets should predict the number of spatial locations that can be recalled. In the experiments reported here the time taken to move between spatial targets is varied by altering the size of targets and the distance between them. No difference between span performance on a nine-block spatial span task were found, either on immediate recall or on recall after an interval. When recall is of items from an array of 27, grouped in nine sets of three, with only one location in any set being presented on any trial, there is an effect of display size. This effect is consonant with the argument that movement time is related to spatial rehearsal, but other explanations are also possible. However, if recall in this task is scored over the nine sets rather than over the 27 items, then there is no difference between the displays. The results indicate that performance on the normal nine-block spatial-span task cannot be predicted by movement time.     

When does length cause the word length effect?

The word length effect, the finding that lists of short words are better recalled than lists of long words, has been termed one of the benchmark findings that any theory of immediate memory must account for. Indeed, the effect led directly to the development of working memory and the phonological loop, and it is viewed as the best remaining evidence for time-based decay. However, previous studies investigating this effect have confounded length with orthographic neighborhood size. In the present study, Experiments 1A and 1B revealed typical effects of length when short and long words were equated on all relevant dimensions previously identified in the literature except for neighborhood size. In Experiment 2, consonant-vowel-consonant (CVC) words with a large orthographic neighborhood were better recalled than were CVC words with a small orthographic neighborhood. In Experiments 3 and 4, using two different sets of stimuli, we showed that when short (1-syllable) and long (3-syllable) items were equated for neighborhood size, the word length effect disappeared. Experiment 5 replicated this with spoken recall. We suggest that the word length effect may be better explained by the differences in linguistic and lexical properties of short and long words rather than by length per se. These results add to the growing literature showing problems for theories of memory that include decay offset by rehearsal as a central feature.     

The effect of an additional task on recall accuracy in serial short term memory: Preemption of rehearsal or acquisition?

In a serial short term memory test, being either visual or auditory, Ss got the additional instruction to make immediate binary classification responses (BcRs) to those items that occured after a marker which was presented somewhere in the list. The results show a general negative effect of BcRs on recall accuracy of both visually and auditory presented lists i.e. both on items which had been classified during presentation and on those which had occured before the marker arrived. The findings are contrary to the view that BcRs preclude acquisition of the items, but the hypothesis is confirmed that BcRs preempt intra trial rehearsal.     

Are multiple visual short-term memory storages necessary to explain the retro-cue effect?

Recent research has shown that change detection performance is enhanced when, during the retention interval, attention is cued to the location of the upcoming test item. This retro-cue advantage has led some researchers to suggest that visual short-term memory (VSTM) is divided into a durable, limited-capacity storage and a more fragile, high-capacity storage. Consequently, performance is poor on the no-cue trials because fragile VSTM is overwritten by the test display and only durable VSTM is accessible under these conditions. In contrast, performance is improved in the retro-cue condition because attention keeps fragile VSTM accessible. The aim of the present study was to test the assumptions underlying this two-storage account. Participants were asked to encode an array of colors for a change detection task involving no-cue and retro-cue trials. A retro-cue advantage was found even when the cue was presented after a visual (Experiment 1) or a central (Experiment 2) interference. Furthermore, the magnitude of the interference was comparable between the no-cue and retro-cue trials. These data undermine the main empirical support for the two-storage account and suggest that the presence of a retro-cue benefit cannot be used to differentiate between different VSTM storages.     

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.     

Articulatory suppression and the irrelevantspeech effect in short-term memory: Does the locus of suppression matter?

Immediate serial recall for letter sequences was impaired when irrelevant speech (IS) was presented throughout stimulus input and a subsequent rehearsal interval. This irrelevant-speech effect was eliminated when participants engaged in articulatory suppression (repeated articulation of one or more digits) during stimulus input but not when suppression occurred during the postinput rehearsal period. Also, changing-state suppression (articulation of multiple items) impaired the overall level of performance more than did steady-state suppression (repetition of a single item), whereas both forms of suppression had the same influence on the IS effect. Our results suggest that the locus of suppression (during or after stimulus input) may have contributed to discrepant findings in the prior literature regarding the influence of articulatory suppression on the IS effect. We consider the implications of our findings for three prominent models of immediate memory: the working memory model, the objectoriented episodic record model, and the feature model.     

A “word length effect”for sign language: Further evidence for the role of language in structuring working memory

We report a sign length effect in deaf users of American Sign Language that is analogous to the word length effect for speech. Lists containing long signs (signs that traverse relatively long distances) produced poorer memory performance than did lists of short signs (signs that do not change in location). Further, this length effect was eliminated by articulatory suppression (repetitive motion of the hands), and articulatory suppression produced an overall drop in performance. The pattern of results, together with previous findings (Wilson & Emmorey, 1997), provides evidence for a working memory system for sign language that consists of a phonological storage buffer and an articulatory rehearsal mechanism. This indicates a close equivalence of structure between working memory for sign language and working memory for speech. The implications of this equivalence are discussed.     

Working memory in multilingual children: Is there a bilingual effect?

This research investigates whether early childhood bilingualism affects working memory performance in 6- to 8-year-olds, followed over a longitudinal period of 3 years. The study tests the hypothesis that bilinguals might exhibit more efficient working memory abilities than monolinguals, potentially via the opportunity a bilingual environment provides to train cognitive control by combating interference and intrusions from the non-target language. A total of 44 bilingual and monolingual children, matched on age, sex, and socioeconomic status, completed assessments of working memory (simple span and complex span tasks), fluid intelligence, and language (vocabulary and syntax). The data showed that the monolinguals performed significantly better on the language measures across the years, whereas no language group effect emerged on the working memory and fluid intelligence tasks after verbal abilities were considered. The study suggests that the need to manage several language systems in the bilingual mind has an impact on children's language skills while having little effects on the development of working memory.     

The co-witness misinformation effect: memory blends or memory compliance?

For 30 years hundreds of researchers have shown participants videos and slide-sequences of events, presented the participants with misleading information, and found that this misinformation distorted their memories. The purpose of this study was to establish whether those misled participants are reporting a memory blend of the two sources of information or whether they are simply complying with the post-event information. A total of 92 participants were shown one of two versions of six different videos, which included some subtle differences. After having watched each video individually, participants were paired with someone who had seen the other version and they discussed the clips together. They then individually answered questions about the videos, and their responses showed that some of the distorted memories were blends of the original information and the post-event information. The implications of these findings are discussed.     

Does neighborhood size really cause the word length effect?

In short-term serial recall, it is well-known that short words are remembered better than long words. This word length effect has been the cornerstone of the working memory model and a benchmark effect that all models of immediate memory should account for. Currently, there is no consensus as to what determines the word length effect. Jalbert and colleagues (Jalbert, Neath, Bireta, & Surprenant, 2011a; Jalbert, Neath, & Surprenant, 2011b) suggested that neighborhood size is one causal factor. In six experiments we systematically examined their suggestion. In Experiment 1, with an immediate serial recall task, multiple word lengths, and a large pool of words controlled for neighborhood size, the typical word length effect was present. In Experiments 2 and 3, with an order reconstruction task and words with either many or few neighbors, we observed the typical word length effect. In Experiment 4 we tested the hypothesis that the previous abolition of the word length effect when neighborhood size was controlled was due to a confounded factor: frequency of orthographic structure. As predicted, we reversed the word length effect when using short words with less frequent orthographic structures than the long words, as was done in both of Jalbert et al.’s studies. In Experiments 5 and 6, we again observed the typical word length effect, even if we controlled for neighborhood size and frequency of orthographic structure. Overall, the results were not consistent with the predictions of Jalbert et al. and clearly showed a large and reliable word length effect after controlling for neighborhood size.     

The role of executive function in autobiographical memory retrieval: does the type of cue word matter?

ABSTRACT

Autobiographical memories are memories for personally experienced life events. Previous research has revealed individual differences in the ability to recall specific memories that happened at a particular time and place. Some studies suggest such differences can be attributed to the varying capacity of executive function. However, little is known regarding which specific executive function skills predict autobiographical memory specificity. Participants were asked to complete multiple measures of executive function as well as an autobiographical memory task in which they were asked to recall a specific personal memory connected to concrete and abstract cue words. We hypothesised that executive function will be positively related to autobiographical memory specificity and that this relation will be moderated by the cue word type. The results revealed that individuals with higher executive function skills, specifically, higher inhibitory control and cognitive flexibility, recalled significantly more specific memories than those with lower executive function skills; however, no significant interaction between executive function ability and cue word type was found.