Selim Onat

I am a neuroscientist working currently on how humans make generalizations based on what they have previously learnt. To do so, I am using a variety of methodologies including fMRI (1), autonomous (2), as well as eye-movement recordings (3).

This research emanates from the well-established field of "stimulus generalization" following mainly the "lineage" of Hovland, Hull and Roger Shepard (4), and including the more recent computational work of Josua Tenenbaum (5). Furthermore, it integrates work on anxiety disorders, as it is believed that these mechanisms are impaired in people suffering from anxiety problems.

In the past, I have been working on how the nervous system processes natural scenes both at the electrophysiological and sensory-motor level. Since the times of Hubel and Wiesel, visual processing had been
overwhelmingly studied with artificial stimuli such as moving edges. However this type of stimuli suffer from an ecological validity problem, as they only rarely occur in real-life. We therefore investigated cortical processing during viewing of natural movies. This previous work focused on visual processing using mostly the technique of voltage-sensitive dye imaging and eye-tracking.

Effect of aversive learning on discrimination of faces

In her Msc thesis, Lea Kampermann shows that humans can perceptually discriminate faces better, when these are paired with an aversive outcome. This effect was specific to the face, which was paired with an aversive outcome and was not observed for the one which was kept neutral throughout the experiment. Furthermore the effect was strongest when these faces were presented at shorter durations (~.6 s) allowing participants to make no more than two fixations per trial.

Her thesis contains also a detailed account on the methodology for generating face-stimuli that are perceptually calibrated to form a two-dimensional similarity gradient with equal perceptual steps between faces. The methodology is an extension of work from Yue et al. (Vision Research, 2012). If you wish to use these stimuli for your experiment they are available upon request.

Perceptually calibrated set of faces according to a simple primary visual cortex forming a circular similarity gradient. Details on their production can be read in Msc Thesis of Lea (please contact any of us for a pdf) .