Comparing the Estimation of Internally and Externally Defined Interval Durations

Abstract

In this thesis I distinguish between two types of temporal intervals: internally-defined and externally-defined. Prior research on how humans estimate the durations of temporal intervals has been focussed almost entirely on externally-defined intervals. Because internally-defined intervals have been largely ignored, our level of understanding of how people estimate the durations of these intervals rests on whether they do so using roughly the same set of mental processes as for externally-defined intervals. I sought to collect some initial evidence regarding whether people do indeed estimate the two types of durations using similar processes. A key finding was that estimating the duration of an externally-defined interval (a stimulus on a computer screen) interfered with performance on a concurrent task whereas estimating the duration of an internally defined interval (a response time) did not (Chapter 2). This finding extended to several different temporal and non-temporal tasks (Chapter 3). The results indicate that processes underlying estimation of internally-defined intervals may differ in meaningful ways from those underlying estimation of externally-defined intervals.