George Stuart

Functional equivalence of verbal and spatial information in serial short-term memory.

Performance on a test of serial memory for the spatial position of a sequence of dots showed similarities to typical results from the serial recall of verbal material: a marked increase in error with increasing list length, a modest rise in error as retention interval increased, and bow-shaped serial position curves. This task was susceptible to interference from both a spatial task (rote tapping) and a verbal task (mouthed articulatory suppression) and also from the presence of irrelevant speech. Effects were comparable to those found with a serial verbal task that was generally similar in demand characteristics to the spatial task. As a generalization, disruption of the serial recall of visuospatial material was more marked if the interference conditions involved a changing sequence of actions or materials, but not if a single event (tap, mouthed utterance, or sound) was repeated.

Think before you speak : pauses, memory search, and trace redintegration processes in verbal memory span

Immediate memory span and speed of memory search were assessed for words and nonwords of short and long spoken duration. Memory span was substantially greater for words than for nonwords and for short than for long items, though speed of memory search was unaffected by either length or lexicality. An analysis of the temporal pattern of responses in the memory span task indicated that inter-item pauses were longer between nonwords than words but that these pause durations were unaffected by item length. A model of verbal short-term memory span is described in which trace selection from a short-term store and the redintegration (restoration) of degraded phonological traces both occur in the pauses between saying successive items. Both trace selection and trace redintegration appear to play important roles in accounting for individual differences in memory span.

High- and low-frequency words are recalled equally well in alternating lists: Evidence for associative effects in serial recall

Three experiments investigate the effects of mixing items of different types in the same list. Experiments 1 and 2 compare the immediate serial recall of high- and low-frequency words in pure and alternating lists. In pure lists high-frequency words are better recalled, but in alternating lists the two types of words are recalled at intermediate, and identical, levels. Experiment 3 compares the recall of words and nonwords. In pure lists nonwords are recalled substantially less well than words. In alternating lists nonwords gain a substantial recall advantage compared to pure lists but are still less well recalled than words, which are recalled at identical levels in both mixed and alternating lists. The results refute item-based redintegration accounts of frequency effects in immediate serial recall and provide evidence for the importance of inter-item associative mechanisms.

Abolishing the Word-Length Effect.

The authors report 2 experiments that compare the recall of long and short words in pure and mixed lists. In pure lists, long words were much more poorly remembered than short words. In mixed lists, this word-length effect was abolished and both the long and short words were recalled as well as short words in pure lists. These findings contradict current models that seek to explain the word-length effect in terms of item-based effects such as difficulty in assembling items, or in terms of list-based accounts of rehearsal speed. An alternative explanation, drawing on ideas of item complexity and item distinctiveness, is proposed.

Priming the identification of environmental sounds.

Three experiments were conducted using a repetition priming paradigm: Auditory word or environmental sound stimuli were identified by subjects in a pre-test phase, which was followed by a perceptual identification task using either sounds or words in the test phase. Identification of an environmental sound was facilitated by prior presentation of the same sound, but not by prior presentation of a spoken label (Experiments 1 and 2). Similarly, spoken word identification was facilitated by previous presentation of the same word, but not when the word had been used to label an environmental sound (Experiment 1). A degree of abstraction was demonstrated in Experiment 3, which revealed a facilitation effect between similar sounds produced by the same type of source. These results are discussed in terms of the Transfer Appropriate Processing, activation, and systems approaches.

From auditory image to auditory percept: Facilitation through common processes?

Two experiments explored implicit memory for auditory stimuli as measured by a test of perceptual identification. The facilitative effect of perceived auditory primes was contrasted with that of imaged auditory primes. In Experiment 1, there was a significant priming effect from imaged spoken-word primes that did not differ significantly from the level of priming due to perceived spoken-word primes, measured by a test of auditory perceptual identification. There was no facilitation of spoken-word identification following creation of an image of a word’s referent sound. In Experiment 2, identification of an environmental sound was facilitated by prior processing of an imaged sound from the same category, though there was significantly more transfer following processing of the actual sound.

The distinctiveness of the word-length effect.

The authors report 2 experiments that compare the serial recall of pure lists of long words, pure lists of short words, and lists of long or short words containing just a single isolated word of a different length. In both experiments for pure lists, there was a substantial recall advantage for short words; the isolated words were recalled better than other words in the same list, and there was a reverse word-length effect: Isolated long words were recalled better than isolated short words. These results contradict models that seek to explain the word-length effect in terms of list-based accounts of rehearsal speed or in terms of item-based effects (such as difficulty of assembling items).

Words fail me: The verbal IQ deficit in inflammatory bowel disease and irritable bowel syndrome

Background: Many chronic illnesses are accompanied by impaired cognitive functioning. In people with Inflammatory Bowel Disease (IBD), there is some research to suggest a decrement in verbal IQ (VIQ), when compared to people with Irritable Bowel Syndrome (IBS) and healthy controls. Although this is an important finding, it is necessary to ensure that such deficits are not due to methodological problems such as the failure to take into account pre‐morbid functioning. Methods: A total of 88 people (IBD, N = 29; IBS, N = 29; Controls, N = 30) completed the Wechsler Abbreviated Scale of Intelligence (WASI), the Wechsler Test of Adult Reading (WATR), the Trait Rumination Questionnaire (TRQ), the Center for Epidemiologic Studies Depression Scale (CES‐D), and the General Health Questionnaire (GHQ‐12). Results: We found evidence of a VIQ decrement in both IBD and IBS groups when measured against both healthy controls and against their own pre‐morbid IQ scores (WTAR‐Predicted WAIS‐III IQ measures). However, the decrement was larger (and of clinical significance) in the IBD group but not in the IBS group. Conclusion: Some tentative evidence is presented which suggests that poor VIQ performance may be due in part to interference from excessive rumination.

Ageing affects conceptual but not perceptual memory processes

Whereas age effects commonly occur in tests of explicit memory, tests of implicit memory often show age invariance. In two experiments, the traditional confound between test type (implicit vs explicit) and retrieval process (conceptually driven vs perceptually driven) was removed by using conceptually driven and perceptually driven tests of both implicit and explicit memory. Experiment 1 revealed a significant age effect for conceptually driven retrieval and no age effect for perceptually driven retrieval, regardless of the type of memory being measured. Experiment 2 highlighted a difference between the two age groups in their ability to utilise semantic encoding in a nominally perceptually driven explicit memory test. The paper concludes that although perceptually driven processing is stable over age, particular care must be taken to minimise contamination from conceptually driven retrieval processes in such investigations.