Signal detection: shifting the response criterion
After learning that a missed tumor could lead to a lawsuit, a radiologist starts calling more ambiguous scans positive. Her ability to tell tumors from normal tissue does not change. Compared with before, what happens?
Answer C: explanation for every choice
A
Raising hits while lowering false alarms would require better discrimination, which the stem rules out.
B
Sensitivity reflects her ability to discriminate, which is unchanged. Only her bias has shifted.
C
Correct. She has adopted a more liberal criterion. Saying “yes” more often catches more tumors but also flags more normal scans, while d′ stays the same.
D
A more conservative criterion would decrease both. She became more liberal.
TakeawayThe criterion trades hits against false alarms. Sensitivity is separate.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID ps146.