Forced confabulation affects memory sensitivity as well as response bias.

A signal detection analysis assessed the extent to which forced confabulation results from a change in memory sensitivity (d(a)), as well as response criterion (β). After viewing a crime video, participants answered 14 answerable and 6 unanswerable questions. Those in the voluntary guess condition had a "don't know" response option; those in the forced guess condition did not. One week later, the same questions were answered using a recognition memory test that included each participant's initial responses. As was predicted, on both answerable and unanswerable questions, participants in the forced guess condition had significantly lower response criteria than did those who voluntarily guessed. Furthermore, on both answerable and unanswerable questions, d(a) scores were also significantly lower in the forced than in the voluntary guess condition. Thus, the forced confabulation effect is a real memory effect above and beyond the effects of response bias; forcing eyewitnesses to guess or speculate can actually change their memory.