High Speed LED Backlight Tachistoscope Reveals Fast Processing of Topological Invariants

Primate visual system is extremely efficient in extracting stable invariants from environment, despite various transformation and degradation. The timing and dynamics of invariants perception provide important constraints for theories of vision. We developed a high speed LED backlight tachistoscope capable to deliver visual stimuli with 1 ms exposure and adjust the duration in submillisecond precision, which enabled us to investigate the relative speed of processing topological, projective, affine, and Euclidean invariants in configural superiority effect paradigm by manipulating the access time to visual input and estimating the psychometric function for sensory evidence accumulation. The results suggest that topological invariant requires shortest exposure time, consistent with the prediction of global-first theory.