Abstract
The visual system compensates for the differences between the peripheral and foveal visual field using different mechanisms (Stewart, Valsecchi & Schütz, 2020). In a previous study, Hübner and Schütz (2021) found a perceptual bias in transsaccadic shape perception. Here, we asked whether similar asymmetries could be found in other visual features and how well the differences in appearance between the peripheral and foveal visual field could explain them. We investigated the perception of spatial frequency changes across saccades. The frequency of Gabor stimuli was varied in 0.25 octave steps in a range of 0.84 to 4.76 cpd. Frequency was either increased or decreased during a saccade. In Experiment 1, participants showed a bias for frequency-increase reports when they had to indicate if the frequency increased or decreased during the saccade. Interestingly, a 200-ms blank improved the precision of the responses (Weiß, Schneider & Herwig, 2015), but left the bias unaffected. In Experiment 2, participants had to estimate spatial frequency of stimuli in the periphery and the fovea separately. There were no differences in the appearance at the fovea and the periphery. In a criterion-free transsaccadic change detection task in Experiment 3, participants showed lower thresholds when frequency increased than when it decreased, indicating that the bias in Experiment 1 was not merely a response bias. Our results show that an increase of spatial frequency across saccades is more readily detected. Since differences in spatial frequency appearance cannot explain this effect, we suspect a more low-level process such as transsaccadic masking (Pisapia, Kaunitz & Melcher, 2010) as a potential underlying mechanism. Lower spatial frequencies are processed faster and with higher sensitivity than higher frequencies (Kaplan & Shapley, 1982). As a consequence, the lower postsaccadic frequency might mask the higher presaccadic frequency and thereby impede change detection.