中華心理學刊 民 80，33 卷，23-58
Chinese Journal of Psychology 1991, Vol.33, 23-58

Gary Chon-Wen Shyi（State University of New York at Stony Brook）

Abstract

The three experiments in the present study examined whether or not the prior orientation of spatial attention to the expected stimulus location aided performance in three same-different tasks differing in complexity: texture discrimination, shape discrimination, and category discrimination. In Experiments 1 and 2 tasks were blocked; hence, subjects knew in advance which discrimination would be required on each trial. In Experiment 3 the tasks were presented in mixed blocks; hence, subjects did not know beforehand which of the three discriminations would be required on each trial. Two sets of main results were found: First, attentional costs and benefits, comparable to those obtained in simple detection tasks, were obtained regardless of task complexity and regardiess of whether tasks were blocked or unblocked. Second, the size of the attentional costs and benefits obtained in the three tasks differed in the mixed-block condition （Experiment 3）, but not in the pure-block condition （Experiments 1 and 2）. The first finding suggests that the processing mechanisms required for completing the various tasks （and in particular, those required for initial shape analysis） can be activated in parallel with those used to orient spatial attention. The implications of the second finding were discussed in terms of a possible inverse relationship between the size of the focus of attention and the speed with which its location can be shifted. In addition, whether the differential costs and benefits of orienting spatial attention should be attributed to task complexity or to task difficulty was also discussed.