Are feature and across-dimension switch costs attentional or decisional?

In a pop-out visual search task, response times to a target are faster when its features or dimensions are repeated than when they are switched. Currently, the origins of these intertrial effects or intertrial switch costs are the basis of great debate within relevant fields of research. According to attentional accounts, feature priming effects and across-dimension switch costs originate in early levels of visual attention which guide attention the target. Alternatively, decisional accounts suggest that across-dimension switch costs originate at a later, post-selectional stage of target selection. Previous research has provided evidence for both views. The current study directly compares switch costs at feature changes and dimension changes using the same set of stimuli within a detection task. Manual response times and eye movements were recorded to determine the origins of feature and dimension switch costs. Results revealed that priming effects facilitate search within feature changes. Eye movement measures also found elongated saccade latencies to targets in dimension switch trials than in feature switch trials. These findings suggest that the early visual selection mechanisms responsible for feature switch costs may differ to those responsible for across- dimension switch costs