Basic Response Time Tools for Studying General Processing Capacity in Attention, Perception, and Cognition

Abstract

One of the more important constructs in the study of attention, perception, and cognition is that of capacity. The authors reviewed some of the common meanings of this construct and proposed a more precise treatment. They showed how the distribution of response times can be used to derive measures of process capacity and to further illustrate how these measures can be used to address important hypotheses in cognition.

Effects of redundant visual stimuli on temporal order judgments

“…Another measure for indexing the effects of redundancy on RT distributions (e.g., Townsend & Nozawa, 1995;Wenger & Townsend, 2000) is the total system capacity up to each time point, C(t), defined as (2) H r (t) is the integrated hazard function for the condition where h r (t) is the hazard function in this condition (see Luce, 1986;Townsend & Ashby, 1983). H 1 (t) and H 2 (t) are the analogous quantities for the two single-stimulus conditions.…”

A strong test of the dual-mode hypothesis

“…As has been discussed by Townsend and Ashby (1978), the (nonintegrated) hazard function on time can be interpreted in terms of instantaneous intensity-that is, the amount of work a system is capable of accomplishing in an instant of time. Its integrated form can then be interpreted in terms of the cumulative amount of work a system is capable of performing up to a particular point in time (for a tutorial discussion of these concepts, see Wenger & Townsend, 2000).…”

“…The issue of capacity is closely related to the issue of independence (Townsend & Wenger, 2004b) and refers to the way in which system performance changes as workload is varied (for discussions, see Townsend & Ashby, 1978;Townsend & Nozawa, 1995;Townsend & Wenger, 2004b;Wenger & Townsend, 2000). For example, if it is assumed that when featural information is augmented by configural information (i.e., if the amount of information to be processed and, thus, the workload are increased) there will be no observable effect on processing efficiency, the perceptual system can be assumed to possess unlimited capacity.…”

An examination of the processing capacity of features in the Thatcher illusion

“…is not yet completed (Wenger & Townsend, 2000). Formally, it is the probability that a response is made at a given time point (probability density function of task completion over time) divided by the probability that a response has not yet been made up to and including a given time point (the survivor function 1 ).…”

“…Given that the hazard function provides a measure of the amount of work done in a given unit of time, its integral provides a cumulative measure of work done (Townsend & Ashby, 1978; see also Wenger & Townsend, 2000). This cumulative hazard function is calculated as the negative log of the survivor function.…”