A three-stage color model - Comment

In a recent Vision Research paper (De Valois & De Valois, 1993), we described what we referred to as the Standard Model of color vision, an attempt to understand certain aspects of visual behavior by reference to the observed characteristics of the anatomy and physiology of the visual system. Although the Standard Model has served us well, its account of several phenomena of interest is less than completely satisfactory. Motivated in part by our recognition of these limitations, and in part by certain new anatomical and physiological reports suggesting that the Standard Model was in error, we reconsidered the problem. We began with the observed characteristics of the anatomy and physiology, at the first two stages of our model, and then postulated a third stage at which we made only minimal assumptions about further processing, asking how well such a simple model could account for various behavioral observations. Guth raises several points with respect to this paper. We respond to each of these points in turn.