Evidence for image-scanning eye movements during transitive inference

Contrary to earlier work, recent studies have demonstrated a reduction in e ye movements during the solution of tasks that seem to require visual image ry, relative to verbal tasks. The present study provides evidence that the nature of the visual imagery required by a task determines whether saccades are evoked and in which spatial pattern. In two experiments, subjects solv ed transitive inference problems with the relational terms left/right and a bove/below, while the horizontal and vertical EOG were recorded. Subjects m ade more horizontal and fewer Vertical saccades while solving problems with the left/right terms than while solving identical problems with above/belo w. The results of silent counting tasks showed that the rate of subvocaliza tion can also influence saccadic rate, especially in the horizontal plane, but cannot explain the eye-movement patterns observed during transitive inf erence. The results are discussed in terms of a motor theory of voluntary t hinking. (C) 1998 Elsevier Science B.V. All rights reserved.