Abstract
Researchers use a wide range of confidence scales when measuring the relationship between confidence and accuracy in reports from memory, with the highest number usually representing the greatest confidence (e.g., 4-point, 20-point, and 100-point scales). The assumption seems to be that the range of the scale has little bearing on the confidence-accuracy relationship. In two old/new recognition experiments, we directly investigated this assumption using word lists (Experiment 1) and faces (Experiment 2) by employing 4-, 5-, 20-, and 100-point scales. Using confidence-accuracy characteristic (CAC) plots, we asked whether confidence ratings would yield similar CAC plots, indicating comparability in use of the scales. For the comparisons, we divided 100-point and 20-point scales into bins of either four or five and asked, for example, whether confidence ratings of 4, 16–20, and 76–100 would yield similar values. The results show that, for both types of material, the different scales yield similar CAC plots. Notably, when subjects express high confidence, regardless of which scale they use, they are likely to be very accurate (even though they studied 100 words and 50 faces in each list in 2 experiments). The scales seem convertible from one to the other, and choice of scale range probably does not affect research into the relationship between confidence and accuracy. High confidence indicates high accuracy in recognition in the present experiments.
Highlights
Psychologists have long wrestled with the issue of how confidence and accuracy of memories are related
As in eyewitness experiments with a single tested face, our studies show that high confidence indicates high accuracy, even in experiments with many events to be remembered
For d′ scores, a one-way between-subjects Analysis of variance (ANOVA) revealed no main effect of the type of scale, F(3,92) = .75, p = .526, η2p = .02, BF01 > 100
Summary
Psychologists have long wrestled with the issue of how confidence and accuracy of memories are related. Dallenbach (1913) showed “observers” (using the terminology of the day) complex pictures for 1 minute each with instructions to remember them. He later tested them 5, 15, or 45 days later. Dallenbach showed that forgetting occurred over time, which is no surprise, and he found that confidence of responses was related to their accuracy. He concluded, “The degree of certainty of the observer’s replies bears a direct relation to the fidelity of the answer” “The degree of certainty of the observer’s replies bears a direct relation to the fidelity of the answer” (p. 335)
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