The characteristics of automatized performance resemble those of preattentive processing in some respects. In the context of visual search tasks, these include spatially parallel processing, involuntary calling of attention, learning without awareness, and time-sharing with other tasks. However, this article reports some evidence suggesting that extended practice produces its effects through different mechanisms from those that underlie preattentive processing. The dramatic changes in search rate seem to depend not on the formation of new preattentive detectors for the task-relevant stimuli, nor on learned abstracted procedures for responding quickly and efficiently, but rather on changes that are very specific both to the particular stimuli and to the particular task used in practice. We suggest that the improved performance may depend on the accumulation of separate memory traces for each individual experience of a display (see Logan, 1988), and we show that the traces differ for conjunction search in which stimuli must be individuated and for feature search where a global response to the display is sufficient.

No abstract