Miller (1956) summarized evidence that people can remember about seven chunks in short-term memory (STM) tasks. How- ever, that number was meant more as a rough estimate and a rhetorical device than as a real capacity limit. Others have since suggested that there is a more precise capacity limit, but that it is only three to five chunks. The present target article brings together a wide vari- ety of data on capacity limits suggesting that the smaller capacity limit is real. Capacity limits will be useful in analyses of information processing only if the boundary conditions for observing them can be carefully described. Four basic conditions in which chunks can be identified and capacity limits can accordingly be observed are: (1) when information overload limits chunks to individual stimulus items, (2) when other steps are taken specifically to block the recoding of stimulus items into larger chunks, (3) in performance discontinuities caused by the capacity limit, and (4) in various indirect effects of the capacity limit. Under these conditions, rehearsal and long-term memory cannot be used to combine stimulus items into chunks of an unknown size; nor can storage mechanisms that are not capacity- limited, such as sensory memory, allow the capacity-limited storage mechanism to be refilled during recall. A single, central capacity limit averaging about four chunks is implicated along with other, noncapacity-limited sources. The pure STM capacity limit expressed in chunks is distinguished from compound STM limits obtained when the number of separately held chunks is unclear. Reasons why pure capacity estimates fall within a narrow range are discussed and a capacity limit for the focus of attention is proposed.

/pdf/the-magical-number-4-in-short-term-memory-a-reconsideration-3704b9phuz.pdf

The magical number 4 in short-term memory: a reconsideration of mental storage capacity.

This study used data from 220 adults to examine the relations among 3 inhibition-related functions. Confirmatory factor analysis suggested that Prepotent Response Inhibition and Resistance to Distractor Interference were closely related, but both were unrelated to Resistance to Proactive Interference. Structural equation modeling, which combined Prepotent Response Inhibition and Resistance to Distractor Interference into a single latent variable, indicated that 1 aspect of random number generation performance, task-switching ability, and everyday cognitive failures were related to Response-Distractor Inhibition, whereas reading span recall and unwanted intrusive thoughts were related to Resistance to Proactive Interference. These results suggest that the term inhibition has been overextended and that researchers need to be more specific when discussing and measuring inhibition-related functions.

The relations among inhibition and interference control functions: a latent-variable analysis.

A latent-variable study examined whether verbal and visuospatial working memory (WM) capacity measures reflect a primarily domain-general construct by testing 236 participants in 3 span tests each of verbal WM, visuospatial WM, verbal short-term memory (STM), and visuospatial STM, as well as in tests of verbal and spatial reasoning and general fluid intelligence (Gf). Confirmatory factor analyses and structural equation models indicated that the WM tasks largely reflected a domain-general factor, whereas STM tasks, based on the same stimuli as the WM tasks, were much more domain specific. The WM construct was a strong predictor of Gf and a weaker predictor of domain-specific reasoning, and the reverse was true for the STM construct. The findings support a domain-general view of WM capacity, in which executive-attention processes drive the broad predictive utility of WM span measures, and domain-specific storage and rehearsal processes relate more strongly to domain-specific aspects of complex cognition.

https://libres.uncg.edu/ir/uncg/f/M_Kane_Generality_2004.pdf

The Generality of Working Memory Capacity: A Latent-Variable Approach to Verbal and Visuospatial Memory Span and Reasoning

tical perspective. For instance, there are only three passing references to kuru in a book of 650 pages. This edition reflects the renewed interest in the immunological theories of multiple sclerosis. More than half the text is devoted to Professor Lumsden's analysis of the pathoIogy and, in particular, the chemical pathology of the immune response. There is a great deal of original work devoted to the chemistry and behaviour of the immunoglobulins. Much of this appears in specialist journals and one must be grateful for the critical summary provided here. Professor Lumsden unequivocally sees the key to the problem of multiple sclerosis in the study of its immunochemistry, relegating infection by a virus or a slow virus to a quite subsidiary role. The clinical studies drawing on wide practical experience help to get one's prejudices about the illness onto a more reasoned footing. The section on treatment is still sadly limited. Dr. McAlpine found little to add to the regime which he described in 1955. McAlpine, Lumsden, and Acheson's reappraisal is an essential reference for the practising neurologist and the new edition makes important modification of and changes in emphasis from the edition of 1965.

https://jnnp.bmj.com/content/jnnp/36/5/894.3.full.pdf

The assessment of aphasia and related disorders

On the capacity of attention: Its estimation and its role in working memory and cognitive aptitudes.

Global matching: A comparison of the SAM, Minerva II, Matrix, and TODAM models.

Phonological similarity is observed to affect serial recall detrimentally when correct-in-position scoring is used. Two experiments investigated the role of item and position accuracy scoring of rhyming, similar nonrhyming, and dissimilar lists under immediate recall conditions; articulatory suppression; or a filled delay. In general, rhyme lists produced the best item recall but position accuracy was highest for dissimilar lists. The results are due to a category cueing effect improving item recall for rhyme lists in conjunction with a detrimental effect of phonological similarity on position accuracy. La similarite phonologique nuit au rappel seriel lorsque l'on considere le nombre de mots rappeles a la bonne position. Dans deux experiences la precision du rappel des items et de leur ordre est evaluee pour des listes qui riment, des listes similaires qui ne riment pas et des listes dissemblables. Ces listes sont utilisees dans une tache de rappel immediat, une tache de rappel avec delai, ou avec suppres...

/pdf/phonological-similarity-and-trace-degradation-in-the-serial-32ejrq5ieo.pdf

Phonological Similarity and Trace Degradation in the Serial Recall Task: When CAT helps RAT, but not MAN

In recent years, a number of memory span findings have been attributed to the operation of an articulatory loop (Baddeley & Hitch, 1974). These attributions have been made on the basis of finding a correspondence between span differences and pronunciation rate differences. This experiment explored articulatory loop explanations for two material effects in memory span: the word-frequency effect (span for high-frequency words is larger than span for low-frequency words) and the word-class effect (span for function words is smaller than span for either nouns or adjectives). The results indicate that it is possible to obtain span differences without finding corresponding pronunciation rate differences. Moreover, span differences were as pronounced under articulatory suppression conditions as they were under rehearsal conditions. Both of these results limit the generality of articulatory loop explanations of memory span.

/pdf/articulatory-loop-explanations-of-memory-span-and-2izm78crd2.pdf

Articulatory loop explanations of memory span and pronunciation rate correspondences: A cautionary note

Empirical data indicate that when memory for subspan lists of taxonomically related material is tested immediately after study, prior experience with lists involving the same material has no effect upon recall or recognition. In six experiments, we explored the possibility that immunity to proactive interference (PI) is related to discriminative information that is provided by transient phonemic codes. In these experiments, we manipulated the strength of phonemic codes as well as their presence or absence. Immunity to PI was found only when it was presumed that a phonemic representation of the target items existed and that information provided discriminative information. In all other cases, PI was observed. The finding that PI effects correspond with the manipulation of phonemic information in a principled fashion provides strong evidence for the role of phonemic codes in producing short-term PI effects.

/pdf/transient-phonemic-codes-and-immunity-to-proactive-42np7ui338.pdf

Transient phonemic codes and immunity to proactive interference.

Some current models of working memory argue that a passive short-term store is not involved in more dynamic working memory tasks. Other models argue that standard short-term memory and working memory tasks rely on common storage facilities. We examine these issues by exploring two signature effects of passive short-term storage in simple span, complex span, and Brown-Peterson tasks. The finding that all three tasks show word length and phonological similarity effects suggests that common processes or storage mechanisms are involved in all tasks. The implications for models of working memory are discussed.

Gerald Tehan

Papers

Global matching: A comparison of the SAM, Minerva II, Matrix, and TODAM models.

Phonological Similarity and Trace Degradation in the Serial Recall Task: When CAT helps RAT, but not MAN

Articulatory loop explanations of memory span and pronunciation rate correspondences: A cautionary note

Transient phonemic codes and immunity to proactive interference.

Word length and phonological similarity effects in simple, complex, and delayed serial recall tasks: Implications for working memory.