[Distracter effect on the right angle perception]

On the monitor three light spots form imaginary sides of the right angle. The perceived angle distortions arose when distracting stripes were flanking each stimulus spot and subjects were asked to readjust the orthogonal orientation of the sides. The dependence of the subject's error value on the spot-to-stripe distance was measured. The data obtained was referred to a certain lateral interaction processes which manifested themselves as a local information averaging concerned with the positions of the stimulus parts. The quantitative parameters of the lateral interaction were established by a simplified mathematical model based on the conception of the centroid biases which are due to summation of the corresponding patterns of excitations in the visual pathways. A good agreement between the computational and experimental data was obtained.