Signal detection theory (SDT) has become a prominent and useful tool for analyzing performance across a wide spectrum of psychological tasks, from single-cell recordings and perceptual discrimination to high-level categorization, medical decision making, and memory tasks. The utility of SDT comes from its clear and simple account of how detection or classification performance can be translated into psychological quantities, such as sensitivity and bias. Whether its use is appropriate for a specific application depends on a number of underlying assumptions, and even though these assumptions are rarely tested, SDT has proved useful enough that it is considered one of the great successes of cognitive psychology. Yet, SDT has also undergone criticism, which began to emerge when this theory was relatively young.
Criticisms of SDTSDT assumes that percepts are noisy and give rise to overlapping perceptual distributions for signal and noise trials. In order to distinguish between signal and noise trials, the observer uses a decision criterion to classify the percepts. Signal responses are "hits" when they are correct and "false alarms" when they are incorrect; similarly, noise responses can be classified as "correct rejections" and "misses." Many criticisms of SDT have centered on how the observer places a decision criterion during a detection or classification task, and whether a deterministic criterion is used at all (see, e.g., Dorfman & Biderman, 1971;Dorfman, Saslow, & Simpson, 1975;Kac, 1969;Kubovy & Healy, 1977;Larkin, 1971).Clearly, when initially performing a signal detection task, 1 an observer may be unable to estimate stimulus distributions and payoff values accurately; thus, one might expect the placement of a decision criterion to improve with experience, approaching a static optimal criterion. Yet, some results suggest that even with extensive practice, responses can be suboptimal: There are numerous demonstrations of human probability micromatching in signal detection tasks (see, e.g., Dusoir, 1974;Lee, 1963;Thomas, 1973Thomas, , 1975 and other demonstrations that static decision criteria are not typically used (e.g., Healy & Kubovy, 1981;Lee & Janke, 1964;Lee & Zentall, 1966;Treisman & Williams, 1984). Despite the fact that models accounting for these dynamics are based on a fairly reasonable assumption (i.e., that the decision criterion should improve with experience), they have not enjoyed the success of classic SDT-probably because they add layers of complexity to the theory that are not easily accommodated or validated. Given that even the basic assumptions required by SDT are rarely tested, it is perhaps not surprising that tests of these additional factors happen even less frequently.
465Copyright 2008 Psychonomic Society, Inc.
THEORETICAL AND REVIEW ARTICLESDecision noise: An explanation for observed violations of signal detection theory
SHANE T. MUELLERIndiana University, Bloomington, Indiana
AND CHRISTOPH T. WEIDEMANN
University of Pennsylvania, Philadelphia, PennsylvaniaIn signal detection the...
