The electrical field in the retina and pattern vision.

1. In the carp's isolated retina a positive potential was produced within and very closely around an illuminated area, and a negative one in the surrounding area. 2. The configuration of the potential recorded at the center of the illuminated part varied with the area of illumination in such a manner that the negative component increased with increasing areas of illumination. This effect was attributed to the summation of negative potentials coming from all parts of the illuminated area. When the central part was isolated from the surrounding area by a mechanical cut, the negative component decreased so that the recorded potential became more positive. 3. The distribution of positive and negative potentials in the retina subjected to stimuli of various patterns was mapped, and the zero-potential line separating the positive field from the negative one was determined for each stimulus. The contour of the zero-potential line was circular for a circle, about triangular for a triangle, but cruciform for a square. 4. The potential fields around Muller-Lyer figures were mapped, and the extent of the positive field was correlated with the perceptual effect of these figures. 5. The electrical field caused by a set of two concentric circles was mapped. The positive field of the inner circle of definite diameter was found to be displaced towards the center, when the outer circle was relatively large, and displacement occurred in the reverse direction when the outer circle was relatively small. These phenomena were correlated with under- and overestimation of the size of the inner circle when viewed within large and small outer circles, and accounted for in terms of interaction between positive and negative potentials.