PUB - Publikationen an der Universität Bielefeld

Public Significance Statement Humans perform saccadic eye movements resulting in two different images of an object: one prior to and one after the movement. Two processing mechanisms, likewise prior to (presaccadic) and after the eye movement (postsaccadic), have been suggested to merge these two images into one. Previous studies showed that the postsaccadic mechanism weights the available inputs according to their reliabilities. The current study showed that the presaccadic mechanism on the other hand does not seem to weight the information according to reliability. It thus strongly suggests that the two transsaccadic processes follow different mechanistic regularities. Faced with inhomogeneous representations, the visual system has to rely on pre- and postsaccadic processing mechanisms to assure perceptual continuity across eye movements. While postsaccadically, memorized peripheral and postsaccadic foveal information are integrated according to their reliabilities, here we investigated whether this also holds true for the presaccadic combination of peripheral input and internal associated foveal images. In three experiments, participants learned associations between objects changing transsaccadically in one feature dimension (spatial frequency in Experiment 1 and color in Experiments 2 and 3). Subsequently, participants judged the respective feature of only peripherally presented objects. Importantly, the reliability of this peripheral input was manipulated by lowering the contrast (Experiment 1) or adding color noise (Experiment 3). We hypothesized that participants' presaccadic peripheral percepts would be biased toward the internal associated foveal image and that the biasing effect would be stronger the lower the peripheral reliability. In all experiments, perception was biased in the direction of the associated foveal image. However, the strength of the bias did not differ between reliability conditions. The presaccadic perceptual bias effect had previously not been tested with the feature color. By showing that yet another feature incorporates prior transsaccadic knowledge, our results highlight the scope of the effect. Furthermore, they point to important differences between pre- and postsaccadic processing mechanisms.