Memory and time of day

Subjects performed a memory task on two occasions, one in the morning and the other in the afternoon. The task comprised two components, one involved immediate recall of sequences of nine digits, the other involved the repeated item technique devised by Hebb (1961), in which one nine-digit sequence is surreptitiously repeated, each repetition being separated by two non-repeated sequences. Performance on the immediate memory task was better in the morning than the afternoon. The repeated item was recalled more accurately than non-repeated items, but this effect was not influenced by time of day. An explanation in terms of the relationship between arousal and memory reported by Kleinsmith and Kaplan (1963) is suggested.