Changes in the appearance of stimuli of very high luminance

"Evidence concerning the absorption of light quanta by visual pigment molecules is used to derive a theoretical relationship between the parameters of light incident on the retina and the output of the receptor cells. This relationship leads to the following prediction: when two retinal areas are illuminated, one very intensely and the other still more intensely, there will be a period of time during which the less intensely illuminated region will appear brighter than the more intensely illuminated one. Data verifying this prediction are presented. When the theoretical treatment is expanded to include certain assumptions about retinal color mechanisms, it provides an explanation of some of the changes in hue that occur when a very intense colored stimulus is viewed steadily." (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1962 American Psychological Association.

Sexual behavior: Ultrasonic postejaculatory song of the male rat

During the refractory period that follows ejaculation, the male rat regularly emits 22-kilohertz vocalizations. These cease after about three-fourths of the total period has elapsed, and this corresponds to an "absolute refractory period" during which the male cannot spontaneously initiate copulation. Similar 22-kilohertz vocalizations occur in other social contexts, and in general they appear to be desist-contact signals.