Curiosity is one of our most fundamental biological drives and it is important for many things we do in our everyday life. Imagine for example that you hear your phone beep in your pocket. Probably, you will feel the urge to check the message right away, even though the message itself likely doesn’t give you a direct reward.
In a series of three studies we aimed to disentangle the contributions of outcome uncertainty and expected value of rewards to curiosity. To this end, we constructed a novel lottery task in which we independently manipulated outcome uncertainty and expected value. We examined how behavioral measures of curiosity and neural activity were modulated by these factors.
We demonstrated that curiosity can be driven by outcome uncertainty, irrespective of reward. The induction of curiosity was accompanied by increased activity in the parietal cortex. When curiosity was relieved by showing the participants the outcome of the lottery, we found increased activity in the insula, orbitofrontal cortex and parietal cortex. Most strikingly, the activity in the insula increased linearly with increasing information update the outcome provided.