Beoadbent's Filter Theory: Postulate H and the Problem of Switching Time

Abstract

Groups of digits were presented binaurally and dichotically to subjects who were asked to recall them. Different rates and patterns of presentation were used, the design being based on that of Broadbent (1954). Broadbent's findings in this field were confirmed. If subjects are presented with simultaneous pairs of digits at a rate of 2 pairs per second dichotically, they cannot recall them if they are asked to alternate between the ears. If however the presentation is staggered, so that although the rate is constant the signals do not overlap, subjects can recall alternately from the two ears. It is suggested that these findings are better interpreted as an interference effect, not a rate effect. Criticism is offered of similar designs to measure “switching rate”. Criticism is also offered of Broadbent's estimate of “perception time” in such experiments. An analysis of the quantity and type of errors made by subjects is given, which suggests that Broad-bent's theory of a short term store on the peripheral side of a selective filter is in need of revision.