The role of temporal frequency in continuous flash suppression: A case for a unified framework

Abstract

In continuous flash suppression (CFS), a rapidly changing Mondrian sequence is presented to one eye in order to suppress a static target presented to the other eye. Targets generally remain suppressed for several seconds at a time, contributing to the widespread use of CFS in studies of unconscious visual processes. Nevertheless, the mechanisms underlying CFS suppression remain unclear, complicating its use and the comprehension of results obtained with the technique. As a starting point, this thesis examined the role of temporal frequency in CFS suppression using carefully controlled stimuli generated by Fourier Transform techniques. A low-level stimulus attribute, the choice of temporal frequency allowed us to evaluate the contributions of early visual processes and test the general assumption that fast update rates drive CFS effectiveness. Three psychophysical studies are described in this thesis, starting with the temporal frequency tuning of CFS (Chapter 2), the relationship between the Mondrian pattern and temporal frequency content (Chapter 3), and finally the role of temporal frequency selectivity in CFS (Chapter 4). Contrary to conventional wisdom, the results showed that the suppression of static targets is largely driven by high spatial frequencies and low temporal frequencies. Faster masker rates, on the other hand, worked best with transient targets. Indicative of early, feature selective processes, these findings are reminiscent of binocular rivalry suppression, demonstrating the possible use of a unified framework