Group aggregates and individual reliability: The case of verbal short-term memory

Abstract

Two experiments examined the generalizability of the effects of word length and phonological similarity with visual and auditory presentation in immediate verbal serial ordered recall. In Experiment 1, data were collected from 251 adult volunteers drawn from a broad cross-section of the normal population. Word length and phonological similarity in both presentation modes significantly influenced the group means. However, 43% of the subjects failed to show at least one of the effects, and the likelihood that effects appeared was highly correlated with verbal memory span. In Experiment 2, 40 subjects of the original sample were retested, 20 of whom had failed to show one or more effects in Experiment 1. Whether or not an effect had appeared for individual subjects on the first test session was a poor predictor of whether the effect would appear on retest. Finally,an analysis of subject reports demonstrated that the patterns of experimental data could be accounted for in part by the strategies that subjects reported using, and the effect of strategy was independent of the effect of span. The implications of these findings for theories of verbal short-term memory are discussed.Current views as to the characteristics of verbal shortterm memory owe much to the discovery and exploration of the effects on immediate serial ordered recall of word length and phonological similarity. The word-length effect refers to the tendency for normal adult subjects to have more difficulty in immediate serial ordered recall of a sequence oflong words (e.g., university, aluminium, hippopotamus, refrigerator) than in that of a sequence of short words (e.g., scroll, switch, zinc, maths). The phonological similarity effect arises from the relative difficulty in serial ordered recall of phonologically similar items (e.g., man, mad, map, mat) compared with recall ofa sequence of items that are phonologically distinct (e.g., day, boy, sup,few). Word-length and phonological similarity effects appear whether the subjects read or listen to the word sequence for recall.These are robust effects that have been replicated widely with a range of materials using groups of normal subjects (e.g., Baddeley, Thomson, & Buchanan, 1975; Caplan, Ro-Part ofthe work on which this paper is based was supported by a travel grant given to the first author from the Trustees of the journal Brain. We are grateful to Alan Baddeley for very helpful discussions on this topic, and to Marc Marschark for useful discussions on the incidence of head injury in the college population. We are also grateful to Nelson Cowan

An Investigation of Verbal Short-term Memory and Phonological Processing in Four Children With Williams Syndrome

“…Indeed phonological factors such as word length and phonological similarity did not consistently influence STM performance in our 4 WS subjects. However, it has to be noted that these effects are not always consistent in normal subjects either; for example, Logie et al (1996) showed that these effects can also be absent in normal subjects. More importantly, the phonotactic frequency effect which was consistently observed in our CA-and VA-matched control subjects, but was strongly reduced or even inversed in the four WS children, further suggests that phonological language knowledge influences less consistently their performance in phonological STM tasks.…”

Interpreting potential markers of storage and rehearsal: Implications for studies of verbal short-term memory and neuropsychological cases

“…In addition, when a subsample of 40 individuals, 20 of whom failed to show one of the expected effects in the four conditions of the original experiment, was retested at a later point, very low test-retest reliability of the size of the phonological similarity or word length effects was observed. Nevertheless, at the sample level Logie et al (1996) found that the absolute size of an individual's phonological similarity or word length effect was related to their level of overall recall, and was related to whether or not participants reported using subvocal rehearsal as a memory strategy. Beaman et al (2008) replicated the finding that the magnitude of the phonological similarity and word length effects shown by adult undergraduates was proportional to individuals' level of recall.…”

“…These authors examined the size of both the phonological similarity and the word length effects shown by a large sample (n = 251) of adult participants drawn from the general population. Logie et al (1996) found that a number of their sample failed to show reliable phonological similarity or word length effects, under conditions of either auditory or visual presentation. The extent to which these effects were absent was not particularly consistent across, and even within, participants, with some individuals showing an absent effect on one measure or in one modality in combination with a reliable effect on the other measure or in the other modality.…”

“…The starting point for our analysis is work by Logie, Della Sala, Laiacona, Chambers, and Wynn (1996), published in this journal. These authors examined the size of both the phonological similarity and the word length effects shown by a large sample (n = 251) of adult participants drawn from the general population.…”

The Mid-Career Award Working out how working memory works: evidence from typical and atypical development

“…However, the data on children's speech rate-span correlations are more equivocal than is often thought (Jarrold & Hall, 2013), and such correlations may be particularly 'noisy' in young children. In addition, a reduction in the size of the word length and phonological similarity effects to non-significant levels in young children may simply reflect the fact that these effects scale proportionally (Beaman, Neath, & Surprenant, 2008;Logie, Della Sala, Laiacona, Chambers, & Wynn, 1996), and are therefore hard to detect in absolute terms among individuals whose overall recall levels are low (Jarrold, Danielsson, & Wang, 2015;Wang, Logie, & Jarrold, in press). Indeed, we have shown that children younger or older than 7 show comparable effects of phonological similarity for visually presented materials when these effects are analysed in proportional terms (Jarrold & Citroën, 2013).…”