GUIDED SEARCH - THE EFFECTS OF LEARNING

The previous report (Efron & Yund, 1996) offered an interpretation of the results of a number of search experiments within the theoretical c ontext of the guided search model of Cave and Wolfe (1990) and Wolfe ( 1994). The present report extends this interpretation to the effects o f extended practice when subjects search for a target defined by its o rientation in the presence of a number of heterogeneous distracter ite ms having differing orientations. Three experiments are described: The first revealed that over the course of 21 experimental sessions exten ding for a period of 6 weeks there were marked decreases in the magnit ude of the reaction time gradient (RTG) and the right visual field sup eriority observed in the previous experiments. This learning persisted for more than 3 years. The second experiment revealed an interference in the capacity to learn to detect a target of one orientation when s ubjects had previously learned to detect a target of a different orien tation at the same locations. The third experiment revealed that the l earning was restricted to the area of the visual field where the targe t had been presented and that subjects could learn to detect two diffe rent targets concurrently. The results of these experiments indicate t hat the learning is orientation-specific and location-specific and is consistent with a localized increase in the selectivity of the top-dow n selection mechanism of the guided search model. (C) 1996 Academic Pr ess, Inc.