A team of neuroscientists has found that the longer people take to decide, the less accurate and confident they are.
Author Roozbeh Kiani from New York University said that in people's daily lives, they make many decisions and sometimes the evidence afforded them is strong, enabling them to decide quickly and accurately, but other times, the evidence is lacking so they take longer to decide and tend to be less accurate.
Kiani continued that human brain can learn that longer elapsed times are associated with lower accuracy and should mean less confidence, adding that brains use this association to calculate confidence, not just based on the available evidence, but also based on how long it takes to gather the evidence.
Co-author Michael Shadlen added that it's an intriguing notion that the brain might convert its data, which is gathered through the senses, into units of 'degree of belief' by combining evidence and elapsed time.
Shadlen continued that those same regularities that support the intuition that time might matter also made it challenging to identify time itself as a player and not just a marker for something else, such as accuracy.
Shadlen said it makes intuitive sense that 'time spent' would serve as a clue about difficulty, proving it in the lab was not easy though.
It has been established that decisions are usually accompanied by a degree of certainty or confidence, a graded belief that our choices will produce positive outcomes. Confidence plays a critical role in guiding our future behavior in complex environments, especially when decision outcomes are delayed and rapid learning is required.
Their results showed that certainty was inversely correlated with reaction times, in other words, the less time it took to make a decision, the more confidence subjects felt about their decisions.
Kiani said that they showed for the first time that the relationship between decision time and confidence is not fully mediated by evidence, elapsed time plays an independent role and in many situations using the elapsed time is advantageous as it offers a computational shortcut and improves the reliability of calculated confidence. However, it also shows that we can dissociate accuracy and confidence by a manipulation like that used in our experiment.
Their findings appear in the journal Neuron.