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Why Do You Ask?

The curious conundrum of curiosity.

Nilay pati via Wikimedia Commons
Hey - What's going on out there?
Source: Nilay pati via Wikimedia Commons

What counts as "curiosity" – and how do we best characterize or define it?

Curiosity has been said to be a form of the intrinsically motivated search for information or knowledge. But how could we test this out?

What if you were shown a brief preview of an upcoming event, and you couldn't in any way influence the outcome: would you be curious to know what happened? Would you be more curious if the preview was more ambiguous?

Testing it out

Five cognitive neuroscientists recently teamed up to tackle this question. The approach they used was at once surprisingly simple, and surprisingly elegant.

The preview image that the researchers used was a picture of a "lottery vase." For example:

W Koutstaal, based on van Lieshout et al. (2018)
Example trials of the "lottery vase."
Source: W Koutstaal, based on van Lieshout et al. (2018)

Each vase contained 20 marbles. A marble could be either red or blue, and marbles of each color were worth a designated number of points (for example, 10 points for red and 90 points for blue). Some vases contained mostly blue marbles, some vases had mostly red marbles, and other vases had an even admixture of about the same number of red versus blue marbles.

Participants were told that, on each trial, one of the marbles would be automatically chosen by the computer, and that they would be given the amount of "points" for that color marble. The selection of the marble would happen entirely automatically; the participant had no choice in the matter of which marble was selected, or how many points they would thereby receive.

There was only one thing the participants could do: Just before learning which marble was selected on each trial, they could indicate how curious they were to see the outcome on a 1 to 4 point scale. Then, on half of the trials, participants were shown the outcome, that is, they were shown which marble color had been selected and how many points they had thereby gained. On the other half of the trials, participants were shown a similar-looking (control) screen, but without ever learning the outcome.

Looking at the results from the full sample of participants (24 young adults) each presented with more than 450 trials, two clear findings emerged.

First, when the marbles in the vase were about equally red and blue, the more curious participants became to know those outcomes. Second, the number of points awarded for each trial had essentially no effect on how curious the participants were.

So, even though people had no influence on the lottery itself they were curious about the outcomes, and their curiosity was systematically greater the more uncertain the lottery was.

But hold on...

But hold on, hold on, you say – not so fast! Does a simple 1 to 4 point self-reported rating of how curious they were really mean that the participants were indeed experiencing more curiosity on the trials with greater outcome uncertainty? Perhaps the participants thought that's what the experimenters hypothesized they would find and – trying to be "good participants" – they responded according to that inferred hypothesis? Or maybe the participants thought that this was just logically how they should respond, even though they didn't actually feel very curious about any of the outcomes?

Fair enough. The researchers took a two-pronged approach to addressing these and other concerns, first changing the task to a more behavioral outcome (not just a self-report) and then looking to see if different levels of curiosity were associated with different patterns of brain activity.

So, you're curious are you? Then how willing are you to wait for the answer?

The researchers repeated their first experiment, but with an added key twist. In the second experiment, a new group of 24 participants was again shown a "lottery vase" with a given percentage of red versus blue marbles, and with a specific number of points for each color. Now, though, participants were given the option to choose to either see what the outcome was, or not.

But if they responded "yes" that they wanted to see the outcome, then they had to wait an additional 3 to 6 seconds before the outcome was presented to them. If they responded "no," the outcome was not presented. In either case, though, just like in the first experiment, the participant had absolutely no influence on the number of points earned.

Were people willing to actually sacrifice a little time in waiting to satisfy their curiosity? And were they more willing to wait on the trials with greater outcome uncertainty even though it also meant they would have to "pay the price" of waiting several seconds to see the outcome (over which they had no influence)?

The answer was again clear: Matching the patterns found in the first experiment, participants' willingness to wait to see the outcomes systematically increased as the uncertainty of the outcome increased. And, again, there was little effect of the expected value of the outcome on their willingness to wait.

So: people were both more curious, and more willing to wait, for information the more uncertain they were... as though gaining information was itself something they valued or was valuable to them!

Tracing the paths of curiosity in the brain

If participants were really more curious the more uncertain the outcomes: might there be a signature of that curiosity in their brains?

To find out, the researchers tested a new group of 24 participants, who were now asked to respond to the lottery vases task while they were in an MRI scanner. Did the amount of neural activity (fMRI signal) in one or more brain regions track with how curious the participants said they were?

If so, was there greater brain activation in those regions when the highly uncertain lottery vases were presented? And what about when the outcome of each lottery vase was shown to the participant: Did brain activation in any regions change right at the point when the outcome of each lottery vase was presented, that is, the precise point at which participants' curiosity was relieved?

Intriguingly, these two different time points in the task were found to be associated with quite different brain activity patterns. Activation in a region of parietal cortex increased at the time when curiosity was first induced.

But when curiosity was relieved, brain activity in frontal regions increased, especially in a region known as the anterior insula and in the orbitofrontal cortex. In the anterior insula, the amount of activity closely tracked with the amount of "news" that was provided.

The more uncertain the outcome, the more vigorously the insula responded when curiosity was relieved. Importantly, the anterior insula is a region that other research has shown to integrate and represent a very wide array of subjective feelings relating to our internal body states, the sensory environment, our goals and so on.

So: it seems that resolving our curiosity through reducing our uncertainty is both something we're willing to pay a cost for (waiting time) and that has a clear and understandable signature in the brain.

To think about

  • Most often curiosity is caused by our becoming aware of our ignorance or uncertainty about something. But then: What leads us to notice our ignorance? To better foster our curiosity every day and during our creative endeavors, could we slow down and intentionally ask ourselves what we may be missing or what it is that we're uncertain about?
  • Could we become more curious about our own (and our teams') efforts to explore or learn? What other sorts of questioning and investigative actions could we take to better understand our world – and to make valuable newness for ourselves and others?
  • When and why do you experience curiosity? What ignites (or dampens) your curiosity? Are you curious about your own curiosity?
  • Do the kittens in the photograph at the top of this post seem to be curious? If so, do you think that they know they are curious? Why would that matter?


Carruthers, P. (2018). Basic questions. Mind & Language, 33, 1–18.

Craig, A. D. (Bud). How do you feel –– now? The anterior insula and human awareness. Nature Reviews Neuroscience, 10, 59–70.

van Lieshout, L. L. F., Vandenbroucke, A. R. E., Müller, J. C. J., Cools, R., & de Lange, F. P. (2018). Induction and relief of curiosity elicit parietal and frontal activity. Journal of Neuroscience, 38, 2579–2588.