Hysteresis in the perception of motion direction as evidence for neural cooperativity.

When elements of a parallel network, such as the human brain, are extensively interconnected, the network can exhibit 'cooperative behaviour'. Such behaviour, which is characterized by order-disorder transitions, multi-stable states, and a form of memory called 'hysteresis', has been observed in human stereopsis and has motivated models of stereopsis that incorporate cooperative networks. More recently, cooperative phenomena have also been observed in human visual motion perception. This report strongly supports a cooperative interpretation of motion perception by demonstrating hysteresis in the perception of motion direction. The results agree quantitatively with a mathematical model incorporating nonlinear excitatory and inhibitory interactions among direction-selective elements.