Extra effort during memory retrieval may be associated with increases in eyewitness confidence

When testifying in court, witnesses are motivated to try as hard as possible to give an accurate account. This study tested the proposition that extra effort by eyewitnesses during a memory test can lead to higher confidence ratings without any accompanying changes in accuracy. Participant-witnesses answered multiple-choice questions about a classroom visitor who had spoken 5 days earlier. In the high-motivation condition participants could earn prizes based on their memory test performance; in the low-motivation condition there were no special incentives. Although the motivation manipulation did not affect mean witness confidence, the confidence-accuracy and effort-accuracy correlations were substantially smaller in the high-motivation condition than in the low-motivation condition. Furthermore, the confidence ratings for those participants who reported expending high levels of effort in both motivation conditions were significantly higher than the confidence ratings for the low-effort participants, despite the fact that response accuracy did not differ as a function of reported effort. These findings have important implications for understanding how pressures to perform well in the courtroom can affect eyewitness confidence.