Stochastic catastrophe analysis of switches in the perception of apparent motion.

Notes that dynamical phenomena such as bistability and hysteresis have been found in a number of studies on perception of apparent motion. The authors show that developments in stochastic catastrophe theory make it possible to test models of these phenomena empirically. Catastrophe theory explains discontinuous changes in responses caused by continuous changes in experimental parameters. The authors propose catastrophe models for 2 experimental paradigms on perception of apparent motion and present experiments that support these models. These models were tested by using an algorithm for fitting stochastic catastrophe models. Exp 1 examined the motion quartet paradigm and Exp 2 examined the luminance contrast paradigm. Both experiments contained 2 subexperiments: one in which only the normal variable was manipulated and one in which a potential splitting variable was also manipulated. A total of 16 Ss participated. The authors derive from catastrophe theory the prediction that a dynamical phenomenon called divergence is necessary when hysteresis is found. This prediction is supported by the data.