Photopic spectral sensitivity of the cat.

Abstract

SUMMARY1. The psychophysical spectral sensitivity of cats was assessed using a two-choice visual discrimination task by determining increment thresholds and critical flicker frequency on white and chromatic backgrounds.2. For large increments, on 0 0, 0 3 and 3 0 cd/M2 white backgrounds, the cats were most sensitive to 497 nm indicating that these backgrounds are scotopic. On 30 and 300 cd/M2 white backgrounds, the cats were most sensitive to about 454 and 561 nm indicating that these backgrounds are photopic. Sensitivity to intermediate wave-lengths indicated independent action of 'blue' and 'green' cones.3. For large increments, thresholds on photopic yellow and magenta backgrounds indicated the additive influence of 'blue' and 'green' cones.4. Spectral sensitivity functions obtained with a critical flicker frequency criterion of 10 Hz on a 30 cd/M2 white background reflected only the activity of the 'green' cone while at 20 Hz the function reflected an additive contribution of both 'blue' and 'green' cones.5. For small increments, on a 30 cd/M2 white or 96 cd/M2 orange background, sensitivity reflected only the activity of the 'green' cone.6. The cat's photopic spectral sensitivity is influenced by the psychophysical test upon which it is based in a manner that is similar to what has been found for other vertebrates. No evidence was found for a 500 nm mechanism active at photopic levels.

Spectral sensitivity of monocularly deprived cats

“…On a 30 cd/m 2 white background, (triangles) all of the data from both deprived and nondeprived eyes could be well fit by two pigment nomograms from polynomial expressions (Dawis, 1981) with peaks around 450 and 560 nm, which characterize cat blue cone and green cone mechanisms, respectively. The data from the nondeprived eye were comparable to the normally raised cats (Loop et al, 1987) and similar results were found in the other three MD cats. Compared to the nondeprived eyes, the deprived eyes suffered an overall sensitivity loss of 1.41 ± 0.76 log units.…”

“…1) from both deprived and nondeprived eyes could be fit by a pigment nomogram with peak around 510 nm, which characterizes the activity of the rod system (Loop et al, 1987). The rod system in the deprived eye exhibited a sensitivity deficit of 1.18 ± 0.49 log units.…”

Escape strategy of Schreiber’s green lizards (Lacerta schreiberi) is determined by environment but not season or sex

“…The latter was suggested by an experiment using painted epoxy-lizard models of Sand lizards (Lacerta agilis), which avoid the effect of different activity levels, and did not find differences between sexes in predation rate (Olsson, 1993). In contrast, mammals have just dichromatic colour vision (Loop et al, 1987;Neitz et al, 1989;Hunt et al, 2011). Hence, the breeding coloration of male L. schreiberi, which include a strong UV component ), may not be so conspicuous for mammal predators, and male lizards might not need to compensate against a mammalian (i.e.…”

Calculating luminous flux and lighting levels for domesticated mammals and birds

“…In humans photopic vision starts at levels at least 100 times below this, although there is a range (called mesopic vision) where both scotopic vision and vision is available to the subject. Studies by Loop et al (1987) on cats and by Nuboer and Moed (1983) on rabbits showed that these animals may use scotopic and photopic vision at different levels from humans although again there is likely to be a mesopic range where the nocturnal/diurnal transition is a continuum rather than an abrupt change. Another perhaps more likely explanation is that it is the loss of acuity as luminance is reduced that interferes with social signalling.…”