The meaning of the Weber-Fechner law and description of scenes in terms of neural networks

Abstract

An attempt was made to determine to which functions of the visual cortex the Weber-Fechner law pertains. Pairs of lines were presented in different halves of the visual field. One of them was a reference line with an unchanged length, and the other (the test line) was of variable length. Psychometric curves reflecting the probability of the answer that the test line was longer than the reference one were plotted. A neuronal scheme for calculating the subjective reference stimulus, which differed from the objective reference stimulus, was proposed. The central zone of the visual field was determined. Two psychometric curves were obtained in the zone of each hemisphere. One of them was based on the results of tests where the test stimulus was presented above the reference stimulus and the other, on those where the test stimulus was below the reference one. The mutual positions of the curves were asymmetric in the hemispheres. One psychometric curve was obtained outside the central zone in each hemisphere. There was no dependence on the positions of the test and reference stimuli. The obtained data, according to which ΔL = const in the central zone and ΔL/L = const outside it, served as the basis for postulating the existence of three neuronal mechanisms. One of them is responsible for the interaction of neural networks between the hemispheres and serves for describing the scene, estimating the perspective, and determining the relative distances between objects. The second and third mechanisms are responsible for the interactions within the left and right hemispheres and serve only for describing the scene. Only the mechanism of describing the scene operates outside the central zone. It is assumed that the three postulated mechanisms, together with the mechanism of image recognition, create the visual image of the world perceived by the brain.