Abstract
The cortical representation of a visual object differs radically across saccades. Several studies claim that the visual system adapts the peripheral percept to better match the foveal view (Bompas & O'Regan, 2006; Valsecchi & Gegenfurtner, 2015; Herwig & Schneider, 2014). Recently Herwig et al. (2015) found that the perception of shape demonstrates this saccade-contingent learning effect. Here, we ask whether this learning actually requires saccades and propose that a more general learning process is involved. We replicated Herwig et al.'s (2015) study and introduced a fixation condition. In an acquisition phase participants were exposed to objects whose shape systematically changed during a saccade, or during a displacement from the periphery to the fovea (without a saccade). Following acquisition, objects were perceived as less (more) curved if they previously changed from more circular (triangular) in the periphery to more triangular (circular) in the fovea. This pattern was seen for both conditions, with and without saccades. We then tested whether a variable delay (0, 250, 500 or 1000 ms) between the presentations of the peripheral and foveal objects would affect their association – hypothetically weakening it at longer delays. Again, we found that shape judgements depended on the changes experienced during acquisition and that they were similar in both the saccade and fixation conditions. Surprisingly, they were not affected by the delay between the two object presentations. These results indicate that even a delay of 1000 ms between the presentation of peripheral and foveal objects supports learning of the correspondence between these two retinal stimulations. These results suggest that a general associative learning process, independent of saccade execution, contributes to the peripheral perception of shape – and our impression of object uniformity across saccades.
Meeting abstract presented at VSS 2016