![]() ![]() Now that the role of noise in decision-making is better understood, future experiments could attempt to reveal how artificial manipulations of the brain contribute both information and noise to a decision. suggest that the brain does not always gauge how reliable evidence is in order to fine-tune decisions. Furthermore, the results presented by Zylberberg et al. In both humans and monkeys, increasing the noisiness associated with the movement of the dots led to faster and more confident decision-making, just as the bounded evidence accumulation framework predicts. ![]() By comparison, the monkeys could indicate that they were not confident in a decision by opting for a guaranteed small reward on certain trials (instead of the larger reward they received when they correctly indicated the direction of motion of the dots). The effectiveness of this technique was confirmed by recording the activity of neurons in the region of the monkey brain that processes visual motion information.Īfter each trial, the humans rated their confidence in their decision. Using a newly developed method, the noisiness of the dot motion could be changed between trials. have now tested these predictions experimentally by getting human volunteers and monkeys to perform a series of trials where they had to decide whether a set of randomly moving dots moved to the left or to the right overall. Counterintuitively, it also predicts that such an increase in noise speeds up decision-making and increases confidence levels. It predicts that increasing the noisiness of the available information decreases the accuracy of decisions made in response. This theory is known as bounded evidence accumulation. ![]() One theory of decision-making is that the brain simultaneously accumulates evidence for each of the options it is considering, until one option exceeds a threshold and is declared the ‘winner’. A longstanding goal in neuroscience is to work out how such noise affects three aspects of decision-making: the accuracy (or appropriateness) of a choice, the speed at which the choice is made, and the decision-maker’s confidence that they have chosen correctly. Many of our decisions are made on the basis of imperfect or ‘noisy’ information. ![]()
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