Surprise, isolation, and structural change as factors affecting recall of a temporal series.

Summary Two experiments are considered which throw light on certain aspects of what has become known as the von Restorff effect. The first is designed to find out whether items in a serial learning task are favoured in recall because unexpected change attracts attention. The results show that change as such, expected or unexpected, has an effect, though unexpected change does have a somewhat greater effect on recall scores. Subjective reports suggest that this is due, at least in part, to the fact that when the instructions are understood they serve to direct attention. The second experiment directly attacks the question of whether ‘isolation’ has any distinct effect on probability of recall, and demonstrates that structural change in a temporal series is the crucial variable.