Abstract
Numerous studies have shown that saliency has a large influence on visual search. In contrast, very little is known about how salient objects are perceived in typical search displays. We measured the perceived contrast of a Gabor stimulus that either had the same orientation as the surrounding distractors or a different orientation. Observers were shown a circular array of eight Gabors and two Gabors were marked as relevant. The task was to judge which of the Gabors in the marked locations had a higher contrast. We observed that the perceived contrast of Gabors with a contrast different from the context increased slightly. In another experiment, we investigated whether contrast enhancement, which we observed for above-threshold Gabors, would help observers to determine the location of a Gabor at contrast threshold. Observers were asked to indicate the position of the Gabor in one of two marked locations while the same six task-irrelevant Gabors as in Experiment 1 were shown. We found that it was more difficult to localize a Gabor that had an orientation different from the surrounding Gabors. Saliency may harm detection for stimuli at threshold while boosting contrast of above-threshold stimuli.
Swiss National Foundation PDFM1-114417.