In the modified task, the reward delay was increased substantially. However, while waiting for the reward, the rats were given the option to abort the trial short of learning whether their decision was right or wrong and return to the beginning to start a new trial. "This new option to abort and restart constitutes a decision that should be made based on the level of confidence about getting a reward," Kepecs said. This is similar to the decision to make a u-turn when not finding the restaurant in the example above: whether and when you will turn back depends on how confident you are about the decision made at the crossroads.
Kepecs and Mainen surmised that if the rats were not confident about their original decision about the smell, they would be more likely to abort the trial. "Ultimately, confidence about getting a reward is a direct function of the animals' confidence about the decision they have just made. In this way we sought to measure a variable internal to the animals how confident they were about whether they made the right choice or not by observing how it influenced their behavior."
The researchers did indeed find that rats preferentially aborted uncertain trials. This showed that they could not only calculate their level of confidence in a given decision, but also use that calculation in subsequent decisions to guide behavior.
Taken together, these experiments reveal "that confidence estimation is not a complex function specific to humans but a core component of the process of
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| Contact: Peter Tarr tarr123@gmail.com 516-367-8455 Cold Spring Harbor Laboratory Source:Eurekalert |