Why do some of our decisions seem to be motivated by a desire to explore the unknown? A research team from École Normale Supérieure has shown that most of these choices are not motivated by curiosity, but by errors caused by the brain mechanisms involved in assessing our options.
When we have various options to choose from, our decisions do not always lead us toward the safest one based on previous experience. This variability, which is characteristic of human decisions, is most often described in terms of curiosity: Our choices are thought to be the reflection of a compromise between exploiting options that are known and exploring others whose outcomes are more uncertain.
Curiosity is even considered to be an attribute of human intelligence — a source of creativity and unexpected discoveries. This interpretation is based on a very strong (although rarely explicitly stated) hypothesis according to which we weigh up our options without ever making any errors.
An Inserm research team from the Laboratory for Cognitive and Computational Neuroscience (LNC2) funded by the European Research Council (ERC) wanted to test this implicit hypothesis upon which many findings are based. The researchers suspected that our capacity to weigh up and review our options is largely overestimated, based on findings published in 2016 in Neuron.
“One of our researchers had previously shown that our capacity to make the right choice based on partial indicators is restricted by errors of reasoning when these indicators are combined, and not by hesitancy at the time of making the choice. So we asked ourselves whether these errors of reasoning could be responsible for some of the choices considered as being a matter of curiosity by current theories. “
To back up their suspicions, the researchers studied the behavior of around 100 subjects using a slot machine-style game that consisted of choosing between two symbols associated with uncertain reward. They analyzed the behavior of the participants using a new theoretical model developed by Charles Findling, postdoc in the team and co-lead author of the article, which takes into account evaluation errors of the symbols.
As such, the authors discovered that over half of the choices usually considered as being a matter of curiosity were in reality due to errors of evaluation.
“This finding is important, because it implies that many choices in favor of the unknown are made unbeknownst to us, without our being aware of it. Our participants have the impression of choosing the best symbol and not the most uncertain, but they do it on the basis of wrong information resulting from errors of reasoning,“
explains team leader, Valentin Wyart.
Anterior Cingulate Cortex Fluctuations
The participants played a slot machine-style game that involved choosing between two symbols associated with uncertain reward. In this example, the participant has to choose between the left-hand symbol that won them money in previous tests, and the right-hand symbol which has not been tried recently, and whose outcome is therefore more uncertain.
The current theories describe this type of choice as being the reflection of a compromise between exploiting known options (in this example, selecting the left-hand symbol) and exploring other more uncertain options (selecting the right-hand symbol).
In order to understand where these errors come from, the researchers recorded the brain activity of some of the participants using functional magnetic resonance imaging.
They discovered that the activity of the anterior cingulate cortex, a region involved in decision-making, fluctuates with the evaluation errors made by the participants. The greater the activity of this region when evaluating the options, the greater the evaluation errors.
“These errors of evaluation could be regulated via the anterior cingulate cortex by the noradrenaline neuromodulator system, controlling the precision of the mental operations performed by the brain,“
Vasilisa Skvortsova, postdoc and co-lead author of the article, says. In other words, our brain is thought to use its own errors to produce choices in favor of the unknown, without relying on our curiosity.
Although these findings may appear surprising, many major discoveries are the result of errors of reasoning: the discovery of America by Christopher Columbus, who believed he had reached the “East Indies” — a navigation error of 10,000 km.
Consider the discovery of radioactivity by Henri Becquerel, who initially thought that the radiation emitted by uranium was due to the re-emission of solar energy; the discovery of the pacemaker by John Hopps occurred when he was attempting to treat hypothermia with the help of radiofrequency.
“The evolution of the species is also based on random variations of the genome — in other words, genetic errors, some of which are retained by natural selection,“
says Wyart. So there is in fact nothing surprising about our brain taking advantage of its errors in order to think outside the box.
 Charles Findling, Vasilisa Skvortsova, Rémi Dromnelle, Stefano Palminteri & Valentin Wyart. Computational noise in reward-guided learning drives behavioral variability in volatile environments. Nat Neurosci , (2019) https://doi.org/10.1038/s41593-019-0518-9
 Drugowitsch, J., Wyart, V., Devauchelle, A.-D. & Koechlin, E. Computational precision of mental inference as critical source of human choice suboptimality. Neuron 92, 1398–1411