Consistency of auditory detection judgments.

• DOI: 10.1037/h0044520
• Publication Date: 2006-06-08T13:05:13Z
• Authors: David M. Green
• Keywords: Judgment; Hearing; Biophysics; Humans; Biophysical Phenomena; Psychophysiology

An observer's decision in a psychoacoustic detection experiment is governed by two broad classes of determinants: (1) external determinants, such as the likelihood of a particular waveform being a signal in noise, and (2) internal determinants, the momentary state of the observer's nervous system, his response biases, or biases as to certain sequences of responses. The aim of the study was to determine, via a measure of the observer's consistency, the relative contribution of these factors. To achieve this end, the audio information presented during a sequence of two-alternative forced-choice trials was taped and repeated to the observer at a later time. The consistency of the observer's judgments was measured by determining a percent agreement score: the percent of times the subject agreed with his previous response on those special trials of the sequence in which no signal occurred on either interval of the forced-choice trial. Percent agreements range between 80% and 55%, depending on the observer and, perhaps, on the signal occurring on the signal trials. A simple linear model is used to establish a lower bound on the ratio of internal to external noise. Unlike some previous experiments, little evidence could be found for large response dependencies in this type of task. That the observer could occasionally hear the signal probably explains why his behavior remained, to a large degree, under stimulus control. [This work was supported in part by the U. S. Army, the U. S. Air Force Office of Scientific Research, and the U. S. Office of Naval Research, and in part by the National Science Foundation (Grant G-21807).]