Signal recognition and the probability-matching decision rule

In a visual binary recognition task in which three levels of signal strength were presented at each of three levels of signal probability, subjects’ behavior was consistent with the signal detection theory notion that the sensory and the decision processes are independent, but did not support the contention that the decision processes obey a likelihood ratio rule. Instead, the evidence suggests that subjects were attempting to probability-match, adjusting the relative frequencies of their responses to correspond with those of the stimuli. The results are discussed in relation to previous findings, against the background of signal detection theory.