Figure 1.
A signal detection theory (SDT) portrayal of performance in a discrimination task with an uncertain response sometimes allowed. The horizontal axis indicates the subjective impression of the trial. The range of subjective impressions engendered by four objective trial levels is also shown (normal distributions). The observer would obey the two criterion lines, making one or the other primary discrimination response for impressions below the left criterion or above the right criterion. Subjective impressions in between would be declined.