Some research on confidence focuses on how your confidence in a belief or evaluation is based on the speed of the thinking you are doing. This research seems inconsistent on the surface. On the one hand, people use the speed of their judgments to determine whether something is familiar. Fast judgments signal that the object being evaluated is familiar, and people should often be confident in their judgments about familiar items. This work suggests people should be confident in fast judgments.

On the other hand, people prize judgments that have been thought through carefully. The effort required for careful thinking leads to slow judgments. This work suggests that people should often be confident in slow judgments.

But people clearly are not confident in every judgment, so it can't be that people are confident about all fast and slow judgments.

This puzzle was explored in a paper by Zakary Tormala, Joshua Clarkson, and my University of Texas colleague Marlone Henderson in a March, 2011 paper in the and Social Psychology Bulletin.

These authors suggested that fast and slow judgments are most useful in different situations. When people are forming an opinion about an item for the first time, then it is better for them to be slow than to be fast, because that would signal to them that they were thinking through the issue carefully. In contrast, when people are expressing an opinion about an item that they have encountered before, then it is better for them to be fast than to be slow. In this case, the speed would suggest that a previous evaluation they made was easy for them to recall.

Tormala, Clarkson, and Henderson provided evidence for this possibility in three studies. In one representative experiment, participants began the study by studying a series of 12 paintings on a computer screen for 10 seconds each for a later test. Then, participants were shown one painting and were asked to evaluate how much they liked it. Some people evaluated a painting that they studied in the first part of the experiment. The rest evaluated a painting they had not seen before.

After making their evaluation, people were told that the software running the study was keeping track of measurements relating to the way students make decisions. They were then given feedback about the amount of time it took them to evaluate the painting. Half the students received (bogus) feedback that their judgment was made more quickly than that of most other students participating in the study, while the other half of the students received feedback that their judgment was slower. After getting this feedback, people rated their confidence in their earlier evaluation of the painting.

The influence of people's belief about the speed of their judgment depended on whether the painting they evaluated was familiar. People who saw the familiar painting were more confident when they were told they made a fast judgment than when they were told they made a slow judgment. People who saw the unfamiliar painting showed the opposite pattern-they were more confident when they were told they made a slow judgment than when they were told they made a fast judgment.

These results suggest that most of us have two different beliefs about what ought to make us confident in judgments. When we are expressing a belief we have already formed, we expect our gut reaction to give us an accurate evaluation. When we are forming an evaluation of a new object, though, we believe that we should think it through carefully.

Finally, these results make clear that it is not so easy to determine how quickly you have made a judgment. In the studies reported in this paper, people took as much time as they wanted to make their judgments. Their beliefs about whether the judgment they made was done quickly or slowly depended on feedback that they were given from the experimenters. More generally, you make judgments about how efficiently you are thinking by comparing yourself to others, because you often do not have an objective standard for measuring speed.

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