Citation

Zwahlen HT. Proc. Hum. Factors Ergon. Soc. Annu. Meet. 1978; 22(1): 115.

Copyright

(Copyright © 1978, Human Factors and Ergonomics Society, Publisher SAGE Publishing)

DOI

10.1177/107118137802200129

PMID

unavailable

Abstract

The first part of this study investigated the visual gap judgment performance of twenty-four subjects (21-37 years old) in the laboratory. A scaled down (1:12) two-dimensional gap display (black on yellow background) representing the front silhouette of a car and a post placed on the right side of the car was viewed by the subjects from a distance of 46 inches (total viewing angle of display 17 degrees). The width of the car represented the standard stimulus and the horizontal adjustable distance between the car and the post (gap) represented the test stimulus. The subjects were required to make a forced choice judgment with respect to whether the test stimulus distance (gap) was larger or smaller than the standard stimulus distance (car width). The subjects were tested twice on the same day, once using the randomized classical psychophysical method and once using the Up and Down Transformed Response (U.D.T.R.) rule. The data from the randomized classical psychophysical method was analyzed using the probit and the Kärber method of analysis. The data from the U.D.T.R. method was analyzed using a modified Wetherill estimation procedure. The second part of this study investigated the visual gap judgment performance and eye scanning behavior of two subjects over two days (seven experiments per day). Horizontal eye movements were recorded with a Biometrics Eye Movement Monitor system. The third part of this study investigated the efficacies of two psychophysical methods: The randomized classical method and the sequential U.D.T.R. rule. The results from part one of this study were used to determine a psychometric perception curve of an "average" human being. A digital computer simulation model was built to represent a human being's gap judgment responses and the experimental gap judgment situation. Each method was simulated for the following parameters: the step size between the stimulus levels, the bias of the starting point, and the selected number of trials in an experiment.

Language: en