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N Charness

Publications and source records attributed to N Charness.

8 recordsLinked to original sources

Learning of a complex arithmetic skill in dementia: further evidence for a dissociation between compilation and production.

An amnesic Alzheimer's Disease patient was tested on his ability to learn an algorithm to square two-digit numbers. The results indicated a dissociation in the patient's ability to execute the individual steps of the algorithm and his ability to combine the steps of the algorithm, the former accounting for almost all of the improvement in response time. The results are discussed in conjunction with findings from Charness et al. (1988) and Milberg et al. (1988) and suggest that skill learning in Alzheimer's Disease may be compromised due to an inability to combine individual steps of a procedure.

Adult

Learning of a complex arithmetic skill in amnesia: evidence for a dissociation between compilation and production.

Two patients with severe amnesia following rupture of anterior communicating artery aneurysms were able to learn a complex algorithm for mentally squaring two-digit numbers. Although both patients learned the algorithm at a similar rate, one patient's improvement was accounted for by savings in the steps of the algorithm. The other patient, however, showed little improvement in the steps while performance of the whole algorithm improved dramatically. Neither patient showed savings in the Hebb Digit Span procedure. The results suggested a dissociation between amnesics in their capacity to learn the constituent "productions" or steps of a skill and their capacity to organize those productions into a single coherent act.

Adult

Teaching an amnesic a complex cognitive skill.

G.P., a Korsakoff's amnesic, was able to learn an algorithm for squaring two-digit numbers mentally over a 7-day period at a rate comparable to that of age-matched controls. He failed to show normal positive transfer to specific problems or to specific numbers used in components of the task. He also exhibited slight improvement in simple naming speed, forward digit span, simple multiplication speed, but no apparent improvement for the recall of repeated supraspan digit strings. He was unable to state the algorithm he had learned to square two-digit numbers, though he could implement it successfully. The results suggest that the compilation of a skill may involve two dissociable components: composition and proceduralization, with the former, but not the latter, occurring at normal rates for Korsakoff's amnesics.

Aged

The role of theories of cognitive aging: comment on Salthouse.

Cognitive models of aging ought, minimally, to simulate age effects for a broad range of tasks, and their underlying assumptions ought to be constrained by existing data on cognitive mechanisms. Salthouse's model (and other parallel distributed-processing network models) meets the first criterion better than it meets the second. Another weakness is in its inability to account for goal-directed behavior. Thus, models like that of Salthouse seem best suited to the description of automatic information processes such as recognition. I conclude that such models are best evaluated in competition with standard symbolic processing models. I introduce simulation of chess position recall by older and younger chess players and compare it with Salthouse's model.

Aged

Aging and skilled problem solving.

Information-processing models of problem solving too often are based on restrictive age ranges. On the other hand, gerontologists have investigated few problem-solving tasks and have rarely generated explicit models. As this article demonstrates, both fields can benefit by closer collaboration. One major issue in gerontology is whether aging is associated with irreversible decrement or developmental plasticity. If both processes occur, then an appropriate strategy for investigating aging is to equate age groups for molar problem-solving performance and search for differences in the underlying components. This strategy was adopted to examine the relation of age and skill to problem solving in chess. Chess players were selected to vary widely in age and skill such that these variables were uncorrelated. Problem-solving and memory tasks were administered. Skill level was the only significant predictor for accuracy in both a choose-a-move task and a speeded end-game evaluation task. Age (negatively) and skill (positively) jointly determined performance in an unexpected recall task. Efficient chunking in recall was positively related to skill, though negatively related to age. Recognition confidence, though not accuracy, was negatively related to age. Thus despite age-related declines in encoding and retrieval of information, older players match the problem-solving performance of equivalently skilled younger players. Apparently, they can search the problem space more efficiently, as evidenced by taking less time to select an equally good move. Models of chess skill that stress that role of encoding efficiency, as indexed by chunking in recall, need to be modified to account for performance over the life span.

Adolescent

Visual short-term memory and aging in chess players.

Young (M = 20 years) and older (M = 54 years) equally skilled chessplayers reconstructed slides of chess diagrams shown for 1, 2, and 4 sec either immediately or following 15 sec of interpolated processing. Recall was more accurate for younger players, with the gap widening as viewing time increased. Interpolated processing decreased accuracy and increased retrieval time equally in the two groups. Measures of chunking indicated no age-related differences. These results imply that there is an age-related deficit in encoding but not retrieval for visual short-term memory. Since young and old were affected equivalently by interpolated processing, it appears likely that they have similar memory consolidation functions. Since the players were equally skilled, the results contradict the view that skill in chess derives primarily from encoding ability.

Adult