Rats showed amnesia for conditioned fear training if given an electroconvulsive shock immediately after training. Retention was unimpaired, however, when the electroconvulsive shock treatment was given 1 day after training immediately after the presentation of the stimulus used in the fear conditioning training. These results support the view that electroconvulsive shock disrupts memory trace consolidation but does not disrupt a recently reactivated memory trace.

This paper reviews current findings and thinking concerning the nature and bases of “time‐dependent” processes in memory storage. Considerable evidence indicates that memory storage can be enhanced or disrupted by treatments of various kinds (such as electrical stimulation and drugs) which influence brain functioning if the treatments are given to animals shortly after training. This evidence supports the view that there are two types of memory processes, short term memory and long term memory. The fixation of long term memory occurs over time following training. We conclude that the bulk of the evidence is consistent with a “dual‐trace” hypothesis and that alternative interpretations of these findings are not well supported. We point out that these studies can only provide indirect evidence of memory processes since they are studies of the susceptibility of memory processes to facilitating and disrupting influences. The treatments can vary in their effectiveness. Several conceptual models of the relationship between short term and long term memory are presented and evaluated. We suggest that the evidence is most consistent with the hypothesis that short term memory processes are different from but essential for the development of long term memory. The final section of the paper reviews recent findings which provide some understanding of the neurobiological bases of the treatments which modify memory storage processes. We suggest that knowledge of the behavioral effects of treatments which influence memory considered together with knowledge of the effects at a neurobiological level may provide some clues to the biological bases of memory.

Four studies are reported examining the development of spontaneous alternation behavior in rats. Spontaneous alternation was found to increase from a rate of around 20% in 15-16 day old rats to around 90% in 100-day olds. Increasing the length of confinement in the 1st chosen goal arm did not affect alternation rates. Spontaneous alternation could be disrupted or facilitated in mature animals by the administration of either scopolamine hydrobromide or physostigmine sulphate, drugs which had no effect on the typical alternation pattern of 16-day olds, but appeared to begin to have an effect at around 24 days. Dose response curves revealed certain age-dose level interactions which were consistent with the hypothesis that cholinergic inhibitory mechanisms in the brain develop gradually in the rat.

Experiments in which male sea lions (Zalophus californianus) were removed and reintroduced into a social group demonstrate that barking by larger males restricts movement and barking by other smaller males. Barking and aggression were primarily directed toward animals of most nearly equal size. Two 6-year-olds seeking to establish and maintain territorial status used aggressive tactics similar to those observed in breeding males in the field.