Authors:

Hodgson, T.L., Bajwa, A., OWEN, A.M. & Kennard, C.

Reference:

Year of publication:

2000

CBU number:

4003

Abstract:

In this paper we describe a novel approach to the study of problem solving involving the detailed analysis of natural scanning eye movements whilst subjects perform the “one-touch” Tower of London task. Subjects viewed a series of pictures showing two arrangements of coloured balls in billiard pockets. Their task was to work out the shortest sequence of movements to rearrange the balls in one half of the display (Workspace) to match the arrangement in the opposite half of the display (Goalspace). Subjects had to plan, rather than execute the moves and then indicate the minimum number of moves the problem could be solved in. Two groups of subjects were presented with an identical set of problems. One group was instructed to solve the problems with the Workspace arrangement in the upper half of the display, whilst the other group were instructed to solve the problems by rearranging the balls in the lower half of the display. For difficult problems, gaze was more likely to be directed towards the Goalspace in the initial period after presentation of each problem picture. Later on in the trial, subjects directed gaze towards locations in the Workspace. Finally, prior to pressing the response key, fixations were once again more likely to land on the Goalspace. This pattern was found regardless of whether the subjects solved the problems by rearranging the balls in the lower or upper visual fields, demonstrating that these biases in fixation correlated with discrete phases in problem solving. A second experiment demonstrated that the pattern of fixations was dependent upon the moves being internally rehearsed by the subject. Marked differences were found in the distribution of fixations made by subjects who solved problems accurately and those who made errors. The results suggest that problem solving proceeds in three stages corresponding to problem assessment, solution elaboration, and solution verification. Efficient performance of the tower of london also requires the capacity to flexibly shift between gaze control strategies, as well as the ability to acquire information through eye movements whilst manipulating information within mental imagery. The role of working memory and the prefrontal cerebral cortex in the task are discussed.