Cyclovergence: the motor response to cyclodisparity.

Static photographic evidence of the occurrence of cyclovergence is presented that supports and extends the result of Crone and Everhard-Halm (1975). Wide-angle complex targets were a necessary condition; simple horizontal line targets were insufficient. Our asymmetrical disparity targets supported in part the conformance of cyclovergence to Hering's Law but raised questions relating to the computational process that also acts to remove cyclodisparity and permits cyclofusion. Saturation and hysteresis nonlinearities were observed.