Do common principles underlie the representation of order in STM and numerical judgment tasks?

Conference (2012, March 29)

Although many studies have explored magnitude effects in numerical cognition, the representation of order information has received only limited interest. We explored the hypothesis that common abstract ... [more ▼]

Although many studies have explored magnitude effects in numerical cognition, the representation of order information has received only limited interest. We explored the hypothesis that common abstract ordinal representations underlie the representation of order information across different domains. We tested this hypothesis by determining the similarity of distance effects in short-term memory (STM) order probe recognition (did ‘8’ occur before ‘5’ in the list ‘3, 6, 5, 4, 8, 7’ presented a few seconds ago?) and in order judgment tasks (does ‘1’ occur before ‘2’), both numerical and alphabetical stimuli were used. In numerical cognition, adjacent numbers are typically judged more slowly than more distant numbers. In fifty healthy adults, we observed significant distance effects across all tasks: in the order judgment tasks, adjacent numbers/letters were judged more slowly than more distant numbers/letters; in the STM tasks, order recognition was slowed for stimuli stemming from adjacent positions in the STM list as compared to stimuli stemming from more distant positions. Regression slopes for distance effects were identical across the different tasks and conditions. Furthermore, the size of distance effects correlated significantly across tasks, except for the order judgment task with numerical stimuli. We will discuss the implications of these results for a hypothetical common representational system of order information in STM and numerical cognition. [less ▲]

An association between short-term memory for order and numerical cognition in 3rd grade kindergarten children.

Conference (2012, February)

Several studies explored the relationship between verbal short-term memory (STM) and numerical cognition, but with inconclusive findings. The present study re-explored this relationship, by adopting the ... [more ▼]

Several studies explored the relationship between verbal short-term memory (STM) and numerical cognition, but with inconclusive findings. The present study re-explored this relationship, by adopting the critical distinction between STM for item information (the items to be retained) and STM for order information (the order of the items within a list). We hypothesized that especially STM for order should be related to the development of numerical abilities, given that recent studies suggest the intervention of common processes during the representation of order information in STM and numerical tasks. We investigated item and order STM abilities and numerical processing abilities in 72 children during their third year in kindergarten. We observed that order STM abilities, but not item STM abilities, correlated significantly with performance on numerical order judgment and calculation tasks. These associations remained after control of interindividual differences in verbal and non-verbal cognitive efficiency. Our results suggest a specific relationship between order STM processes and numerical cognition, opening new perspectives for our understanding of the STM determinants of numerical cognition development. [less ▲]

The importance of distinguishing item and order memory for understanding short-term memory deficits in brain-damaged patients

Poster (2011, October 18)

Selective verbal short-term memory (STM) deficits are rare and are often associated with a history of aphasia, raising doubts about the selectivity of these deficits. We explore here the distinction ... [more ▼]

Selective verbal short-term memory (STM) deficits are rare and are often associated with a history of aphasia, raising doubts about the selectivity of these deficits. We explore here the distinction between STM for item information (the items and their phonological and semantic characteristics) and STM for order information (the order of items within a list) to separate STM and language impairment. Recent models of STM consider that STM for item information depends upon activation of the language system, and hence item STM deficits should be associated with language impairment. By contrast, STM for order information is considered to recruit a specific system, distinct from the language system. Hence, order STM should be impaired in patients with language-independent STM deficits. We applied this rationale to the exploration of STM profiles of two patients with a history of aphasia, MB and CG. At the time of this study, patient MB showed poor digit and word STM spans associated with a mild impairment at the level of phonological input processing. Patient CG showed poor STM spans with no residual language impairment. A first experiment assessed STM for order and item information, using order and item probe recognition tasks. Patient MB showed severely impaired performance in the item condition (Z=-4.71; p<.001) but a milder deficit in the order condition (Z=-2.17; p<.05). CG on the other hand showed perfectly preserved performance for the item condition (Z=-0.43) but significantly slowed response times for the order condition (Z=-2.20; p<.05). In a second experiment determining item and order error proportions in an immediate serial recall task for six-word lists, MB showed a significantly increased proportion of item errors (Z=-3.24 and -2.6 for positions 5 and 6, respectively; p<.05) but not of order errors (Z=-1.47), while CG showed perfectly preserved item recall (Z=0.22) but an increase of order errors especially in final list positions (Z =-2.57 for position 6; p<.05). A third experiment assessed reconstruction of serial order for digit lists showing perfectly preserved performance in patient MB (Z=1.32) but severely impaired performance in patient CG (Z=-3.49; p<.05). A final experiment assessed new word learning performance, given that STM for order has been shown to be a critical determinant of vocabulary acquisition in children and adults. CG showed impaired new word learning performance in a paired associate word-new word learning experiment (Z=-3.29; p<.05) but not in a word-word learning control experiment (Z=0.13), while MB showed a more general verbal learning impairment (word-nonword: Z=-3.09, p<.05; word-word: Z=-4.8, p<.05). This study provides the first demonstration of a dissociation between STM for order and STM for item information in patients with a history of aphasia, and further shows that patients with residual language impairment are more likely to present impaired STM for item information which is considered to depend on the integrity of the language system. Order STM deficits on the other hand may represent what is commonly referred to as selective STM impairment, highlighting the importance of distinguishing between item and order STM processes when exploring STM deficits in aphasic patients. [less ▲]