Fig. 5.

Limitations of standard SDT tasks. SDT tasks such as the detection task illustrated here cannot distinguish fixed from flexible decision rules when the means and variances of internal measurement distributions can also vary across conditions. (A) Fixed and (B) flexible decision rules give the same behavioral data (perceptual sensitivity, $d\prime$, and criterion, $c$) in the two depicted scenarios, in which attention affects the measurement distributions differently (compare the invalid distributions in A and B). An experimenter could not infer from the behavioral data which scenario occurred.