Projects

Visual size illusions, in which the size of an object is perceived to be larger or smaller than it really is, have been utilized for over a century to study the process of size perception. We recently described a novel illusory effect that is well-illustrated by our Dynamic Ebbinghaus illusion (Mruczek et al., 2015; see video to left). In this illusion, the combination of expanding inducers and target motion yields a stronger illusory effect than the classic, static illusion; in contrast, the expanding inducers in the absence of additional target motion yields a weaker effect than the static illusion. Thus, the effect depends critically on the interaction between size-contrast and motion leading to changes in the contributions of different cues (e.g., angular size and relative size) to perceived size.

We are currently exploring the effects of motion dynamics on other classic size illusions, such as the Corridor and Ponzo illusions.

Electroencephalography (EEG) is a non-invasive methods suitable for studying human visual perception. However, EEG is limited in spatial resolution and is subject to artifacts from eye and muscle movements. Tripolar concentric ring electrodes offer a potential solution to both of these issues (Koka & Besio, 2007).

In collaboration with colleagues at the University of Nevada, Reno, we are currently testing the suitability of tripolar EEG for the study of visual-evoked potentials (VEPs). In particular, we are applying multivariate statistical analyses to quantify how the information content of the tripolar EEG signal compared to that collected from conventional disc electrodes.