Emotional trauma in rats: Age as a factor in recovery

Old (7 months of age) and young (2 months) male rats were divided into groups matched for spontaneous exploratory activity and for age. Experimental rats in the two age categories were then traumatized by giving them a 90 volt shock to the feet for two sec. on only one occasion. It was shown that nearly all the young rats recovered from the trauma within 5 weeks, as measured by brief exploratory activity and defecation, while at the end of 6 months the old rats still had not recovered. These results point up the greater resiliency of young animals, and the need for caution in the interpreting of research and theories on early experience.     

Memory for the pitch of a tone

Observers attempted to detect the presence of a pitch difference between two successive tones. The percentage of correct judgments was equivalent for tones separated by .95, 4.5, and 8.9 sec. There was a general increase in reports of a pitch difference with increased intertone interval, which is interpreted as arising from hypothesized shifts in the neural locus of the first stimulus during the intertone interval.     

Binocular summation in the perception of form at brief durations

Visual form identification at brief durations was studied under: (a) monocular presentation; (b) dichopic presentation where the same form was presented successively on noncorresponding areas; and (c) dichopic presentation where the same form was presented on corresponding areas simultaneously and successively. Form identification for noncorresponding area dichopic presentation was at the level to be expected from 2independent chances to perceive. Both simultaneous and successive dichopic presentation on corresponding areas gave identification accuracy significantly above the level predicted by the assumption of independence. However, the binocular summation was not complete. When the same amount of energy entering the visual system in a binocular presentation was given in a monocular stimulation, the latter condition gave significantly better identification.