Invariant recognition drives neural representations of action sequences
  Recognizing the actions of others from visual stimuli is a crucial aspect of human visual perception that allows individuals to respond to social cues. Humans are able to identify similar behaviors and discriminate between distinct actions despite transformations, like changes in viewpoint or actor, that substantially alter the visual appearance of a scene. This ability to generalize across complex transformations is a hallmark of human visual intelligence. Advances in understanding motion perception at the neural level have not always translated in precise accounts of the computational principles underlying what representation our visual cortex evolved or learned to compute. Here we test the hypothesis that invariant action discrimination might fill this gap. Recently, the study of artificial systems for static object perception has produced models, CNNs, that achieve human level performance in complex discriminative tasks. Within this class of models, architectures that better support invariant object recognition also produce image representations that match those implied by human and primate neural data. However, whether these models produce representations of action sequences that support recognition across complex transformations and closely follow neural representations remains unknown. Here we show that spatiotemporal CNNs appropriately categorize video stimuli into actions, and that deliberate model modifications that improve performance on an invariant action recognition task lead to data representations that better match human neural recordings. Our results support our hypothesis that performance on invariant discrimination dictates the neural representations of actions computed by human visual cortex. 
Andrea Tacchetti and Leyla Isik and Tomaso Poggio
q-bio.NC