MDB: additivity, transitivity, proportionality demonstrated physiologically

Abstract

In the minimally distinct border (MDB) method two fields are precisely juxtaposed and the observer adjusts their relative radiances until the border between them appears minimally distinct. Fraunhofer was the first to use MDB as a method of visual photometry.1 In 1968, Boynton and Kaiser reintroduced MDB as a photometric technique and showed additivity of luminances.2 Lee et al3 recently demonstrated that the neurophysiological substrate of MDB was evident in the phasic, spectrally nonopponent, M-pathway ganglion cells. They moved a heterochromatic border across the receptive field of monkey (M. fascicularis) retinal ganglion cells and measured the spike rate as a function of the luminance ratio across the border of the bipartite field. They determined that the spectral sensitivity of m-pathway cells closely matched the human 10°V(X) function. As a photometric method, MDB obeys the rules of transitivity, additivity, and proportionality. We demonstrate these properties in the nonopponent, m-pathway ganglion cells of the macaque monkey.