D-MAX FOR STEREOPSIS DEPENDS ON SIZE, NOT SPATIAL-FREQUENCY CONTENT

Stereoacuity depends not only on the carrier frequency of Gabor stimul i, but also upon their size. To determine if this is also the case at large disparities, we have measured the upper limit for stereopsis, '' D-max'', and assessed its dependence on carrier frequency and overall envelope size. The results differ markedly from the stereoacuity data. D-max for stereopsis is primarily dependent on the size of the envelo pe of the Gabor patch, and is relatively independent of its carrier fr equency. These results support the proposition that stereopsis is achi eved at large disparities by way of non-linear processing (envelope ex traction).