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Type 2 tasks in the theory of signal detectability: Discrimination between
correct and incorrect decisions
Galvin, S. J., Podd, J. V., Drga, V., and Whitmore, J.
Psychonomic Bulletin & Review, 2003
10 (4), 843-867
Abstract
It has been known for over 40 years that there are two fundamentally
different kinds of detection tasks in the theory of signal detectability. The
Type 1 task is to distinguish between events defined independently of the
observer; the Type 2 task is to distinguish between one’s own correct and
incorrect decisions about those Type 1 events. For the Type 1 task, the behavior
of the detector can be summarized by the traditional receiver operating
characteristic (ROC) curve. This curve can be compared with a theoretical ROC
curve, which can be generated from overlapping probability functions conditional
on the Type 1 events on an appropriate decision axis. We show how to derive the
probability functions underlying Type 2 decisions from those for the Type 1
task. ROC curves and the usual measures of performance are readily obtained from
those Type 2 functions, and some relationships among various Type 1 and Type 2
performance measures are presented. We discuss the relationship between Type 1
and Type 2 confidence ratings and caution against the practice of presenting
transformed Type 2 ratings as empirical Type 1 ratings.
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Last updated
08 Nov 2009 04:37 PM
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