Citation

Varey CA, Mellers BA, Birnbaum MH. J. Exp. Psychol. Hum. Percept. Perform. 1990; 16(3): 613-625.

Affiliation

University of California, Berkeley 94720.

Copyright

(Copyright © 1990, American Psychological Association)

DOI

unavailable

PMID

2144575

Abstract

This study investigated the processes that underlie estimates of relative frequency. Ss performed 4 tasks using the same stimuli (squares containing black and white dots); they judged "percentages" of white dots, "percentages" of black dots, "ratios" of black dots to white dots, and "differences" between the number of black and white dots. Results were consistent with the theory that Ss used the instructed operations with the same scale values in all tasks. Despite the use of the correct operation, Ss consistently overestimated small proportions and underestimated large proportions. Variations in the distributions of actual proportions affected the extent to which Ss overestimated small proportions and underestimated large proportions in the direction predicted by range-frequency theory. Results suggest that proportion judgments, and by analogy probability judgments, should not be taken at face value.

Language: en