NACS Seminar: Dr. Ralf Haefner (U of Rochester)

Behavioral and neural signatures of approximate hierarchical inference

Abstract: Since motion can only be defined relative to a reference frame, which reference frame guides perception? A century of psychophysical studies has produced conflicting evidence: retinotopic, egocentric, world-centric or even object-centric. I will present our recent work on a hierarchical Bayesian model mapping retinal velocities to perceived velocities as well as the psychophysical data that support the critical predictions of our model, and that allow us to infer the subjective set of references frames used by individual observers. Our model provides a quantitative normative justification for key Gestalt principles providing inspiration for building better models of visual processing in general. If time permits, I will also present work on the neural basis of our model, both by linking it to divisive normalization, as well as by describing a general method for testing Bayesian models using neural data.

Bio: Dr. Ralf Haefner is an Associate Professor at the University of Rochester.

The NACS Seminar Series bring NACS faculty and students together on a weekly basis. The speakers are world-class neuroscientists and cognitive scientists who are working at the cutting edge of their discipline. Seminars are held on Fridays from 10:15 AM to 11:30 AM in room 1103 in the Bioscience Research Building. Titles will be posted as they become available. For additional information, please contact Claire Morse at cmorse@umd.edu. NACS seminars are not recorded.