The role of payoffs and signal ratios in criterion changes during a monitoring task.

Forty-eight subjects detected a long-duration. Change in brightness of an electroluminescent panel during a 60- min. monitoring session. Signal / non-signal ratios and payoffs were combined factorial in a between-subject design. Signal ratios affected both the percent of signal detections and the percent of false-alarm errors. When subjects monitored under the lower signal ratios, a decrease in percent of signal detections occurred over time. Payoffs affected only the percent of false-alarms in the higher signal rate conditions. it was concluded that signal ratios rather than payoffs play the major role in determining decision performance in simple visual monitoring tasks.