Puneeth Chakravarthula receives his PhD
The well-earned doctorate reflects Dr. Chakravarthula's novel contributions to understanding the connection between how we look at faces and how the brain encodes them
Congratulations to former VIU graduate student, and current VIU postdoc, Puneeth Chakravarthula on successfully defending his dissertation thesis titled “Long-term visual experience shapes neural representations of faces".
Faces are unique. They involve specialized neural mechanisms and are associated with distinctive behavioral effects. Puneeth's dissertation examined how invariant properties in experiencing faces might shape neural representations and impact behaviors. He focused on two invariances in our visual experience of faces: one arising from the prolonged use of a consistent oculomotor strategy to view faces and the second arising from a preponderance of viewing faces in an upright configuration. He studied the extent of the influence on behaviors and the possible computational mechanisms. In the first part of his thesis, Puneeth showed how long-term oculomotor strategies–variations on where a person looks at a face, e.g. closer to the eyes vs. tip of the nose or mouth–influences two prominent face-effects: the composite face effect and adaptation face-aftereffect. In the 2nd part of the thesis, he investigated how long-term experience with upright faces might shape neural computations. Using a psychophysics paradigm in which faces were revealed through apertures of different sizes he showed that upright faces but not inverted faces are associated with superior spatial integration. Using a convolutional neural network that was trained on upright or inverted faces he show that the network developed superior spatial integration abilities only for the orientation of faces it was trained on. Moreover, the divergence in spatial integration for upright vs. inverted faces only appears in the last layers of network with large receptive fields, supporting the hypothesis that higher visual areas in the brain mediate the upright/inverted face dissociation in processing. Together, Puneeth's research furthers our understanding of the unique perceptual and computational consequences of visual experience to faces. Aside from the energy that Puneeth has dedicated to research, he has shown equal commitment and dedication to undergraduate mentoring leading to the first research experiences and publications for many UCSB students. He has similarly always shown incredible generosity and solidarity with other graduate students in the lab. He will be missed by all of us in the lab.
