Gallagher, S., & Alsop, B. (2001).
Effects of response disparity on stimulus and reinforcer control in human detection tasks.
Journal of the Experimental Analysis of Behavior,
75, 183-203.
In two detection experiments, university students reported
whether the second of two sequentially presented tones was longer
or shorter than the first by responding to stimuli presented on a
touch screen. Stimulus disparity and response disparity were
manipulated to compare their effects on measures of
discrimination and response bias when the reinforcement ratio for
correct responses was asymmetric. Choice stimuli consisted of
squares filled with different pixel densities. Response disparity
was manipulated by varying the difference in density between the
two choice stimuli. In both experiments, decreasing stimulus
disparity reduced discrimination but had no consistent effect on
bias. Decreasing response disparity also reduced discrimination
in both experiments, and often reduced estimates of bias. The
effects of response disparity on bias were most clear in
Experiment 2, in which a greater overall level of response
disparity was arranged. The data show that, like corresponding
research with pigeons, detection performance of human subjects
can be conceptualized as discriminated operants.
Key words: detection, stimulus control, reinforcer control,
discrimination, response bias, touch screen, humans