Abstract
Several theories and models of visual search assume that search efficiency is improved by the use of inhibitory tagging. Hulleman (2009) found no difference in search slopes between search amongst static items and amongst moving items. So, if there is indeed inhibitory tagging of items, it would seem that the tag travels with the item. This hypothesis was tested in two experiments. In the first experiment, where participants had to search for a T amongst L's, there was again no difference between search amongst static (0.0 deg/s) and amongst moving items (7.2 deg/s) in either search slopes or error rates for displays with up to 36 items. In the second experiment participants searched for a square with a notch in the top left corner amongst squares with a notch in one of the other corners. This is a very difficult search task. Although search slopes for static (0.0 deg/s) and for moving (7.2 deg/s) item displays were again very similar, there was now a clear difference in error rates: there were more errors for the moving items. Critically, the maximum display size in this experiment was 18 items; only half the size used in the first experiment. Taken together, these two experiments suggest that there is a fundamental difference in the processes involved in very difficult visual search tasks on the one hand and easier visual search tasks on the other. Whereas the former operate at an item by item level, with only limited robustness against motion, the latter operate above the level of individual items and offer extensive robustness against motion. A theoretical framework that encompasses these findings will be presented.
This research was supported by a small grant from the Experimental Psychology Society.