Total Presentation Time Research Articles

How much help do repeated presentations give to recognition processes?

A recent experiment by Haber and Hershenson (1965) had shown that in a recognition task one long look at a stimulus was always superior to two or more shorter looks summing to the same total presentation time. In order to explore this more fully and to account for opposite results in a different type of recognition task, as well as in a serial learning task, an improved replication of the earlier study was carried out using very short durations and single letters as stimuli. The same non-reciprocity was found, again strongly favoring duration over repetition as a determinant of clarity of a percept, even though repetition alone was also shown to be a significant independent variable. As a subsidiary finding, an error analysis showed that when a letter was misnamed it was nearly always confused with one that looked like it rather than one that sounded like it. Some discussion was offered as to the role of an auditory information storage in low memory load tasks such as this one, as well as some general implications for information processing analyses of the non-reciprocity of duration and repetition.

EFFECTS OF A SUBSIDIARY TASK ON SHORT‐TERM MEMORY

If there is a limited‐capacity mechanism in STM then introducing a concurrent subsidiary task should adversely affect recall. Two experiments on free recall were conducted with card sorting as the subsidiary task. In the first experiment subjects dealt cards into one pile, into two piles by colour, or into four piles by suit while lists of common English words were being read. Subjects sorted cards only during presentation of the lists. As the subsidiary task became more demanding the number of words correctly recalled decreased. In the second experiment sorting by suit was combined with free recall, and the payoffs (relative importance of the two tasks) were varied. Performance on both the recall and the card sorting tasks deteriorated as the other task was stressed. Differences in recall could not easily be attributed to differences in original learning, and the results suggested that the subsidiary task interfered with rehearsal and/or decreased total presentation time for free recall.