Stimulus Set and Response Set: The Alternation of Attention

Abstract

Recently Gray and Wedderburn showed that if a meaningful phrase of three words was presented together with three digits, in such a way that each ear received some items of each of the two types of material, it was no harder to recall the items grouped by type than it was to recall them grouped by ear. This finding is repeated and confirmed in several forms, culminating in the use of three letters of the alphabet and three digits as the six items presented. It is also shown, however, that even when all material is presented to one ear, it is harder to recall a list made up of alternate items of two classes than it is to recall the same items arranged as two successive sub-lists. Thus Gray and Wedderburn's result does not appear to reveal a situation in which alternation of attention between the ears is especially easy, but rather one in which continued attention to one ear is especially difficult because it requires alternation between classes of item. A further series of experiments showed that a reduction in the presentation rate of stimuli produced a much greater improvement in performance when the items were of two alternated classes than when the classes were left separate. Equally, a slow presentation rate is more helpful when alternation between ears is required than when each ear is to be dealt with separately. These results support the idea that attention takes time to shift; but require a separate kind of attention, to a class of item rather than to a source of stimulation.