Evoked potentials to dynamic random-dot correlograms in monkey and man: a test for cyclopean perception.

I I:\TRODl:C"IO~ tor constructed by Walter KroptJ at Bell-Labora­ tories. The stimuli to the left eye were fed directly into , Recently it has been shown that dynamic random-dot the red channel and those to the right eye were fed stereograms (Lehman and Julesz. 1978) and dynamic I into the green channel of a projection TV set random-dot correlograms (Julesz el ai.. 1978, 1979) (ADVENT Videobeam IOOOA). Positive and negative evoke large cortical potentials measured on the binocular correlation alternated at 0.5 Hz. Stereo sep­ human scalp. The latter technique is of particular aration was achieved by placing Kodak Wratten red interest since dynamic random-dot correlograms are and green filters over the red and green projection easy to generate and permit the observer to inspect optics and using identical red and green filters in the the stimulus from any head position. Dynamic ran­ goggles worn by the observers. both monkey and dom-dot correiograms consist of sequences of binocu­ human. The stereo-images were rear-projected onto a larl)' identical noise alternating with binocularly nega­ 144 x 144 cm (122 x 122 deg) translucent screen. One are similar to dynamic picture element (I x 0.5 cml correspondecf'io 86 x 43 are devoid of min arc. monocular cues and thus permit assessment of bino­ Gold-plated Grass cup electrodes were attached to cular jnformation processing. In the present study we the subject's scalp at three positions: the ground elec­ evoke cortical potentials to dynamic trode on the forehead. the positive electrode halfway random-dot correlograms in the alert macaque mon­ between the vertex and nasion (and on the monkey key in order to compare them with human evoked sideways by 3.S em to avoid the headmount post) potentials and to develop a fast. objective test for cyc­ and the negative electrode 2 em above the inion for humans and O.S em above the inion for the monkey. The subject's electroencepnalogram was first ampli­