The time-course of global precedence and consistency effects.

The global precedence effect refers to the finding that global aspects of a scene are processed more rapidly than local detail in the scene. In experiments with large Hs and Ss (global stimuli) made up of small Hs and Ss (local stimuli), choice reaction time (RT) to the global letters is shorter than RT to the local letters (global precedence effect). In addition, RT for local letters is shorter when the local letters are the same as the global letter (consistency effect). We sought to determine the time course of the global precedence and consistency effects by delaying the global information relative to the local information. In Experiment I, the middle cross-bar of the global letter (S or H) was presented followed by the rest of the global letter at delays of 0, 48, 80, 160, 320 and 640 ms. The results indicated that the global precedence effect was obtained at delays < 48 ms and local precedence effects are obtained at delays > 80 ms. Consistency effects were found in the absence of global precedence effects, but only at delays of 48 and 80 ms. Experiment II was a replication with delays of 16, 32, 48, 64, 80, and 96 ms. The results of this experiment were in agreement with those of Experiment I. These findings offer support for the notion that the consistency effect is mediated by a higher level process than is the global precedence effect.