A tacit but fundamental assumption of the Theory of Signal Detection (TSD) is that criterion placement is a noise-free process. This paper challenges that assumption on theoretical and empirical grounds and presents the Noisy Decision Theory of Signal Detection (ND-TSD). Generalized equations for the isosensitivity function and for measures of discrimination that incorporate criterion variability are derived, and the model's relationship with extant models of decision-making in discrimination tasks is examined. An experiment that evaluates recognition memory for ensembles of word stimuli reveals that criterion noise is not trivial in magnitude and contributes substantially to variance in the slope of the isosensitivity function. We discuss how ND-TSD can help explain a number of current and historical puzzles in recognition memory, including the inconsistent relationship between manipulations of learning and the slope of the isosensitivity function, the lack of invariance of the slope with manipulations of bias or payoffs, the effects of aging on the decision-making process in recognition, and the nature of responding in Remember/Know decision tasks. ND-TSD poses novel and theoretically meaningful constraints on theories of recognition and decision-making more generally, and provides a mechanism for rapprochement between theories of decision-making that employ deterministic response rules and those that postulate probabilistic response rules.

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Older adults exhibit a disproportionate deficit in their ability to recover contextual elements or source information about prior encounters with stimuli. A recent theoretical account, DRYAD (Benjamin, 2010), attributes this selective deficit to a global decrease in memory fidelity with age, moderated by weak representation of contextual information. The predictions of DRYAD are tested here in three experiments. We show that an age-related deficit obtains for whichever aspect of the stimulus subjects’ attention is directed away from during encoding (Experiment 1), suggesting a central role for attention in producing the age-related deficit in context. We also show that an analogous deficit can be elicited within young subjects with a manipulation of study time (Experiment 2), suggesting that any means of reducing memory fidelity yields an interaction of the same form as the age-related effect. Experiment 3 evaluates the critical prediction of DRYAD that endorsement probability in an exclusion task should vary nonmonotonically with memory strength. This prediction was confirmed by assessing the shape of the forgetting function in a continuous exclusion task. The results are consistent with the DRYAD account of aging and memory judgments and do not support the widely held view that aging entails the selective disruption of processes involved in encoding, storing, or retrieving contextual information.

We collected category fluency data from several moderate-to-large samples of participants at three different sites: the New York University Aging and Dementia Center, the Oregon Health Services Aging and Dementia Research Center, and the Einstein Aging Study at the Albert Einstein College of Medicine. These data were analyzed by calculating the average relative frequency (e.g., typicality) of the category members generated by each participant. Alzheimer's disease (AD) patients recalled fewer atypical members of common taxonomic categories than did the elderly control group. In addition, the probability of producing an item declined at a greater rate for AD patients than for the elderly control group over the duration of the task. According to sequential sampling models, this latter result implies that the rate at which AD patients search memory must be slower than the search rate of the elderly controls.