A Psychophysiological Test of Depression-Related Probability Bias

Depressive symptom severity was indeed correlated with skin conductance response (SCR) amplitude upon reading uncertain (‘might’) sentences, and this could not be accounted for by overall SCR responsiveness, learning processes, or intolerance of uncertainty. Unexpectedly however, this correlation was negative, indicating that participants with higher symptom scores tended to show smaller SCRs to uncertain cues. It is possible that more-depressed participants tended to hold pessimistic expectancies before they saw each sentence, and so were less surprised to learn that a shock may be imminent.

These results suggest that depression-related pessimism and probability bias are more complex than they appear, and show the importance of combining self-report measures with other methods when studying cognition in depression.