Interaction between rod and cone systems in dichoptic visual masking

Abstract

SUMMARYThe brightness of a brief flash of ligh'; is reduced by the sui4~able presentation of a second flash in an adjacent region of the visual field. This masking effect (metacontrast) can be induced dichoptically, that is with the test flash presented to one eye and the masking flash to the other. By a suitable choice of wavelengths and conditioning field, the test flash may be arranged to effectively stimulate only rod receptors and the masking flash only cone receptors. A dichoptic masking effect is still obtained. The rod and cone receptor mechanisms of the human visual system function independently in dark-adaptation ~md certain increment threshold measurements [8,16,19,29,22]. Interaction between the tw(, receptor systems has, however, been demonstrated in other increment thr~:~hold determinations [ 7,12], in the production of some chromatic effects [ 1~,:L7,23t, in the cancellation of mesopic flicker [11 ] and in a particular movement illusion [6]. F~r the visual masking effect known as metacontrast [ 1,9,18], where the brightness of a flash of light is reduced if it is followed a short time later by a second flash to an adjacent region of the retina, da~a showing both rod-cone independence [2land rod-cone interaction [5] have been obtaine~. These studies have used monoptic stimulation, that is, both test a,-,d n ~asking flashes presented to the same eye. The present work is concerned with rod-cone interlction when the met2contrast is produced by dichopt'.c stimulation, that in, the test flash presented to one eye and the masking flash to the other [see refs. 10,14 and 21]. Evidence that under such conditions the metacontras~ is not specific to a pa~icular class of receptor has already been reported [24].,The experiments reported here were carr:.ed out while the author~ were in the Department of Physics, Imperial College of Science and Technology, London, Great Britain.

The signal‐to‐noise characteristics of rod—cone interaction

“…The proposed signal-to-noise model requires that qualitatively similar rod-and cone-related responses sum at a common neural locus. This could be within the cerebrum as proposed by Latch & Lennie (1977) and Foster & Mason (1977) on the basis of behavioral data; in the absence of relevant anatomical or physiological data, we consider this possibility no further. Unlike lower vertebrates, mammalian rods and cones fail to converge on the same second order neurone so a distal retinal mechanism accounting for the present data would likely involve direct rod-cone coupling.…”

Meta- and paracontrast reveal differences between contour- and brightness-processing mechanisms

“…Kolers and Rosner (1960), using a form identification task, report optimal paracontrast suppression at relatively short SOAs of À40 ms (mask precedes the target). On the other hand, several investigators (Cavonius & Reeves, 1983;Foster & Mason, 1977;O ¨g ˘men et al, 2003) who employed a brightness perception task obtained optimal paracontrast at longer SOAs ranging from À100 to À200 ms. To more firmly test this hypothesis, we compared paracontrast masking in a contour identification task to paracontrast in a brightness matching task. The methods of procedure were identical to those used in the metacontrast experiment, except that the target-mask SOAs now assumed the following values: 0, À10, À20, À40, À60, À80, À110, À140, À170, À200, À350, À500, and À750 ms.…”

Recent models and findings in visual backward masking: A comparison, review, and update

“…Nonetheless, as was noted by Breitmeyer (1984, chap. 4), the exact shape, magnitude, and optimal masking SOA is also influenced by properties of mechanisms located as early as the receptor level (Foster, 1976(Foster, , 1978(Foster, , 1979Foster & Mason, 1977). Although the mechanisms at the peripheral level of visual processing may affect the shape or magnitude ofthe metacontrast function, the consensus among current theoretical approaches to metacontrast (see above) is that the mechanism responsible for the U-shaped masking effect is VISUAL BACKWARD MASKING 1585 cortical.…”