Adaptive shortening of a saccade influences the metrics of other saccades within a spatial window around the adapted target. Within this adaptation field visual stimuli presented before an adapted saccade are mislocalized in proportion to the change of the saccade metric. We investigated the saccadic adaptation field and associated localization changes for saccade lengthening, or outward adaptation. We measured the adaptation field for two different saccade adaptations (14 deg to 20 deg and 20 deg to 26 deg) by testing transfer to 34 different target positions. We measured localization judgements by asking subjects to localize a probe flashed before saccade onset. The amount of adaptation transfer differed for different target locations. It increased with increases of the horizontal component of the saccade and remained largely constant with deviation of the vertical component of the saccade. Mislocalization of probes inside the adaptation field was correlated with the amount of adaptation of saccades to the probe location. These findings are consistent with the assumption that oculomotor space and perceptual space are linked to each other.

Schnier F, Lappe M. Differences in intersaccadic adaptation transfer between inward and outward adaptation. J Neurophysiol 106: 1399 -1410. First published June 15, 2011 doi:10.1152/jn.00236.2011.-Saccadic adaptation is a mechanism to increase or decrease the amplitude gain of subsequent saccades, if a saccade is not on target. Recent research has shown that the mechanism of gain increasing, or outward adaptation, and the mechanism of gain decreasing, or inward adaptation, rely on partly different processes. We investigate how outward and inward adaptation of reactive saccades transfer to other types of saccades, namely scanning, overlap, memory-guided, and gap saccades. Previous research has shown that inward adaptation of reactive saccades transfers only partially to these other saccade types, suggesting differences in the control mechanisms between these saccade categories. We show that outward adaptation transfers stronger to scanning and overlap saccades than inward adaptation, and that the strength of transfer depends on the duration for which the saccade target is visible before saccade onset. Furthermore, we show that this transfer is mainly driven by an increase in saccade duration, which is apparent for all saccade categories. Inward adaptation, in contrast, is accompanied by a decrease in duration and in peak velocity, but only the peak velocity decrease transfers from reactive saccades to other saccade categories, i.e., saccadic duration remains constant or even increases for test saccades of the other categories. Our results, therefore, show that duration and peak velocity are independent parameters of saccadic adaptation and that they are differently involved in the transfer of adaptation between saccade categories. Furthermore, our results add evidence that inward and outward adaptation are different processes.

Schnier F, Lappe M. Mislocalization of stationary and flashed bars after saccadic inward and outward adaptation of reactive saccades. J Neurophysiol 107: 3062-3070, 2012. First published March 21, 2012 doi:10.1152/jn.00877.2011.-Recent studies have shown that saccadic inward adaptation (i.e., the shortening of saccade amplitude) and saccadic outward adaptation (i.e., the lengthening of saccade amplitude) rely on partially different neuronal mechanisms. There is increasing evidence that these differences are based on differences at the target registration or planning stages since outward but not inward adaptation transfers to hand-pointing and perceptual localization of flashed targets. Furthermore, the transfer of reactive saccade adaptation to long-duration overlap and scanning saccades is stronger after saccadic outward adaptation than that after saccadic inward adaptation, suggesting that modulated target registration stages during outward adaptation are increasingly used in the execution of saccades when the saccade target is visually available for a longer time. The difference in target presentation duration between reactive and scanning saccades is also linked to a difference in perceptual localization of different targets. Flashed targets are mislocalized after inward adaptation of reactive and scanning saccades but targets that are presented for a longer time (stationary targets) are mislocalized stronger after scanning than after reactive saccades. This link between perceptual localization and adaptation specificity suggests that mislocalization of stationary bars should be higher after outward than that after inward adaptation of reactive saccades. In the present study we test this prediction. We show that the relative amount of mislocalization of stationary versus flashed bars is higher after outward than that after inward adaptation of reactive saccades. Furthermore, during fixation stationary and flashed bars were mislocalized after outward but not after inward adaptation. Thus, our results give further evidence for different adaptation mechanisms between inward and outward adaptation and harmonize some recent research.

The gist of a visual scene is perceived in a fraction of a second but in change detection tasks subjects typically need several seconds to find the changing object in a visual scene. Here, we report influences of scene context on change detection performance. Scene context manipulations consisted of scene inversion, scene jumbling, where the images were cut into 24 pieces and randomly recombined, and scene configuration scrambling, where the arrangement of the objects in the scene was randomized. Reaction times, where significantly lower in images with normal scene context. We conclude that scene context structures scene perception.