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.     

Information and the memory span

Messages differing in number of symbols and symbol information load were presented tachistoscopically to 4 adult Ss. The messages were constructed by random drawing with replacement from an alphabet of 8 black form symbols and an alphabet of 32 colored form symbols. The number of symbols recalled varied as a function of alphabet; however, the information in recall was constant for all conditions. The number of symbols recalled and the information in recall was independent of message length.     

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.