Brightness function: Binocular versus monocular stimulation

A dozen observers matched numbers to the apparent brightness of a target viewed by one eye or by both eyes. Brightness grew as a power function of luminance, and the functions were practically identical for the two modes of viewing. Throughout its course, the obtained binocular function tended to fall about a decibel above the monocular function. This small degree of binocular summation, of the order of a jnd, mayor may not be significant.