本研究中的三個實驗檢驗導引空間注意力至預期的刺激位置是否會幫助在三種複雜程度不同之辨別異同作業的表現：質地辨別、形狀辨別、及類屬辨別。實驗一、二中作業是分開的，所以受試者事先知造在每一嘗試所要做的辨別作業。實驗三中作業則是混合呈現，也就是受試者事先並不預知在每一嘗試所要做的辨別作業。研究發現兩項主要的結果：第一、不論作業的複雜度，也不論作業是分開或混合呈現，類同於簡單偵測作業所發現的注意力盈虧亦在本研究中獲得。第二、三種作業注意力盈虧的大小在混合呈視時（實驗三） 有差異，但是在分開呈現時則無（實驗一、二）。第一項結果顯示完成各種作業所需要的處理機制（特別是用來處理早期的形狀訊息者）可以和導引空間注意力的機制平行啓動。第二項發現的意義則就注意力焦點的大小及其移動速度之間的可能反向關係加以討論。此外作業複雜度抑或作業困艱度造成對盈虧效應有所差異之影響亦在文中討論。

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 regardless 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.