Presentations at APCV 2016 in Perth

Our lab is presenting some recent results at the Asia Pacific Conference on Vision (APCV 2016) in Perth, Western Australia.

Aaron is showing results of his experiments on a novel “motion smoothness aftereffect”, and Gerrit is presenting results  showing that gaze direction can adapt to stimulus displacements after a single eye blink.

Abstracts are included below:

Adaptation to velocity profiles of random moving dots: A motion “smoothness” aftereffect

Jit Wei Ang, Gerrit Maus

Previous reports of motion adaptation range from low-level adaptation of speed and direction to high-level adaptation of biological motion. However, little is known about potential mid-level processes that could contribute to higher-level aftereffects. Using random dot kinematograms, we adapted observers to two velocity profiles with matched average speed: sinusoidal variations in velocity (“smooth” or constant speed with abrupt direction reversals (“jerky”). Subsequently, we tested perception of different velocity profiles that ranged from smooth to jerky by either morphing the smooth and jerky profiles with a “neutral” (Gaussian) profile, or by varying the ratio of smooth and jerky dots. In a 2AFC task, observers judged which of two differently adapted stimuli looked smoother. All observers judged subsequent stimuli as “jerkier” after adapting to “smooth” motion and vice versa. Adaptation to different velocity profiles is unlikely to depend on lower-level adaptation, but might contribute to higher-level aftereffects, as in biological motion.


Adaptation of gaze direction following single eye blinks

Gerrit Maus, Therese Collins

When a target is displaced repeatedly during eye blinks, the oculomotor system adapts: the initial gaze direction after each eye blink becomes biased towards the new target position, without the subject noticing. Previously shown for repeated identical displacements, we now present evidence of such gaze adaptation after random target steps, and after just one blink. Observers were instructed to fixate a target dot. Eye blinks triggered random target steps left or right (between 0.1 and 1.0 degrees), and observers reported the perceived direction of each step. The change in gaze direction from one blink to the next correlated with the retinal position of the target after the previous blink. This correlation was reduced when observers perceived the previous step accurately. This is evidence for a fast-acting adaptive mechanism that compensates for oculomotor noise when visual changes during blinks are not perceived as object motion.

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