Abstract
In simple visual search tasks repetition of spatial context reduces RTs when the context is predictive of target location (Chun & Jiang, 1998, Cognitive Psychology, 36, 28–71). To analyze how far cueing effects can be generalized to other tasks, in this study we tried to reproduce contextual cuing in a different kind of visual search: comparative search. In each trial, the screen was divided in two halves and an identical random configuration of eight elements (red and green squares and circles) was presented in each. Both halves differed either on one element’s color or shape. In each trial participants had to find the element that was different and indicate the differential feature. Four configurations were repeated 14 times along the experiment, intermixed with newly generated configurations. For each of the repeated configurations the critical item always appeared at the same location, but the differential feature varied across repetitions. Eye movements and RTs were recorded during the task. Results showed no differences on average RTs between repeated and new configurations. However, since RTs in these tasks are clearly affected by the cognitive processes involved in confirming the mismatch, we performed a more detailed analysis of eye fixations. Following the methods described by Pomplun (Pomplun et al, 2001, Cognitive Science, 25, 3–36) trials were divided in two phases: Search and Verification, and all fixations detected in each trial were categorized in one of these groups. The effect of repetition was calculated separately for the average fixation count for each phase. Results showed that Verification fixations decreased significantly more in number over epochs for repeated configurations. Search fixations, however, did not vary between repeated and new configurations. This suggests that, in comparative visual search, contextual cueing effects do not facilitate search, but optimize the verification process prior to response.
Acknowledgement: Research supported by grant PSI2013-43742.