Distinctions have been proposed between systems of reasoning for centuries. This article distills properties shared by many of these distinctions and characterizes the resulting systems in light of recent findings and theoretical developments. One system is associative because its computations reflect similarity structure and relations of temporal contiguity. The other is "rule based" because it operates on symbolic structures that have logical content and variables and because its computations have the properties that are normally assigned to rules. The systems serve (...) complementary functions and can simultaneously generate different solutions to a reasoning problem. The rule-based system can suppress the associative system but not completely inhibit it. The article reviews evidence in favor of the distinction and its characterization. (shrink)

61 subjects were given the task of solving a problem having four possible solutions. "Two cords were hung from the ceiling, and were of such length that they reached the floor. One hung near a wall, the other from the center of the room. The subject was told, 'Your problem is to tie the ends of these two strings together.' He soon learned that if he held either cord in his hand he could not reach the other. He was then (...) told that he could use or do anything he wished." A number of objects which might help in the solution of the problem were present in the room. After each solution had been mastered the subject was told to solve the problem in still another way until all of the solutions had been learned. The trials were timed and introspective reports concerning the means of solution were recorded. A number of hints were given from time to time when the subject failed to reach a solution. The author's conclusions are to the effect that "The perception of the solution of a problem is like the perceiving of a hidden figure in a puzzle-picture. In both cases the perception is sudden; there is no conscious intermediate stage; and the relationships of the elements in the final perceptions are different from those which preceded, i.e., changes in meaning are involved." The author feels that trial and error or association by similarity cannot explain his results. (shrink)

This paper reports a study of the roles of visuo-spatial and verbal working memory capacities in solving a planning task - the five-disc Tower of London (TOL) task. An individual differences approach was taken. Sixty adult participants were tested on 20 TOL tasks of varying difficulty. Total moves over the 20 TOL tasks was taken as a measure of performance. Participants were also assessed on measures of fluid intelligence (Raven's matrices), verbal short-term storage (Digit span), verbal working memory span (Silly (...) Sentence span), visuo-spatial short-term storage (Visual Pattern span and Corsi Block span), visuo-spatial working memory (Corsi Distance Estimation), visuo-spatial processing speed (Manikin test), and verbal speed (Rehearsal speed). Exploratory factor analysis using an oblique rotation method revealed three factors which were interpreted as (1) a visuo-spatial working memory factor, (2) an age-speed factor, and (3) a verbal working memory factor. The visuo-spatial and verbal factors were only moderately correlated. Performance on the TOL task loaded on the visuo-spatial factor but did not load on the other factors. It is concluded that the predominant goal-selection strategy adopted in solving the TOL relies on visuo-spatial working memory capacity and particularly involves the active ''inner scribe'' spatial rehearsal mechanism. These correlational analyses confirm and extend results previously obtained by use of dual task methods, (Phillips, Wynn, Gilhooly, Della Sala, & Logie, 1999). (shrink)

This paper reports a study of planning processes in the five-disc Tower of London (TOL) task in 20 younger and 20 older adult participants. A concurrent direct ''think-aloud'' method was used to obtain data on planning processes prior to moving discs in the TOL. A check was made of the effects of verbalising by comparing performance data from the experimental groups with data from control groups who did not verbalise during planning or moving. Verbalising slowed down planning and moving but (...) did not appear to distort the participants' approaches to the task. Older and younger participants did not differ in average moves taken to solve the tasks. However, older participants' planning was less complete and more error-prone than that of younger participants. The planning processes were characterised as showing a means-ends ''goal selection'' strategy. In this strategy participants (1) identify a single active goal disc at the start, (2) select moves and move sequences to enable the placing of the current goal disc in its target position, and (3) continue in this way until all discs are in their target positions. Age differences were found in the planning stage, during which there was no stimulus support and hence a substantial working memory load. During the move phase there was stimulus support and hence little loading of working memory. Age differences in moves required were not found in the move phase. As older participants tend to have depleted working memory capacity the present results suggest that working memory is heavily loaded in TOL planning but less so in the move phase of TOL. (shrink)