Abstract
Recent studies have established that fixational saccades may improve the visual performance in difficult tasks demanding the efficient processing of fine details (Ko, Poletti & Rucci, 2012). On the other hand, Rucci et al. (2007) suggested that the specific effect of fixational eye movements is to reduce the impact of low-frequency noise, by flattening the spectrum typical of natural visual scenes. We investigated whether fixational saccades can be adaptively modulated in a visual detection task in order to maximize stimulus-related information. In a grating detection task, with a 2-interval forced choice paradigm, we used 3 frequencies and 4 contrast levels. In each trial, in one interval a vertical oriented grating was presented superposed with a pink noise, while in the other interval the noise was presented alone. Eye movements were recorded with an Eyelink 1000 video-based eye tracker. We found that saccade amplitude was largely dependent on noise, and this pattern did not vary significantly with grating frequency or contrast. However, a large proportion of saccades were perpendicular to grating orientation, suggesting that saccade direction is mainly controlled by grating orientation and by strategy of spatial information gathering.
Meeting abstract presented at VSS 2013