Selim Onat

My main occupation is Neuroscience.

In the past, I have been interested on how the visual system processes natural scenes. To this end, I have recorded naturalistic movies using micro-cameras carried by cats while they were actively exploring a natural environment. I used these movies to train neuronal networks in an unsupervised manner and compared learnt features to the known properties of neurons in visual cortex. I also used these videos as stimuli during physiological recordings to gain insights on the principles of natural signal processing in the visual cortex.

Recently, I started working on how humans make generalizations based on what they have previously learnt. To this end, 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.

Singing Gabors: Visual stimulus locking of EEG is modulated by temporal congruency of auditory stimuli

























In this study, we used the Singing Gabors.

These consist of Gabor functions, where one of the parameters (here orientation parameter) is modulated either in a congruent or incongruent way with the audio signal.

Guess which of the following videos is the congruent one:







In the congruent case, the audio signal's frequency changes simultaneously with  the orientation of the Gabor. This leads (in my case) to a vivid illusion of agency, meaning that I perceive the animated Gabor function as if it was producing the sound itself (the paper deals with much simpler questions though).

In the incongruent case, the audio signal is orthogonal to the changes in the orientation parameter of the Gabor function. Still it is interesting to realize how human perception is biased for fusing these two as if they were congruent.