Immediate memory in dialling performance with and without simple rehearsal

This experiment was designed to explore the effects of simple rehearsal on immediate memory in telephone dialling performance in a sample of 36 men aged 45 to 60 for whom data on intelligence, vocabulary, emotional stability and occupation were available.

The eight-digit messages were the same as those previously used by Conrad in a study of telephone operators which compared performance on dialling and keysender equipment. Using a Latin square design, subjects were required to dial 10 eight-digit messages in each of six conditions (three with auditory and three with visual presentation). Dialling was carried out (1) immediately the message had been presented; (2) after it had been once vocally rehearsed by the subject; (3) after it had been written down while being vocally rehearsed. A complete record was obtained of all performances, at rehearsal and at dialling.

It was found that with auditory serial presentation, immediate vocal rehearsal and immediate dialling are equally good and both superior to dialling which followed vocal rehearsal. With visual simultaneous presentation, immediate vocal rehearsal is clearly superior to dialling with or without rehearsal, which do not differ. Performance after written-down rehearsal was the worst in both modes of presentation.

A non-linear relationship between intelligence and performance was found, and acute individual differences in performance were observed among the subjects of the highest intelligence.