You know you are going to receive an electric shock. But you have the opportunity to choose whether you will receive the shock immediately or a bit later. What will you choose? Given the choice, many people choose to get it over with immediately. Theories about decision assume that the choice of early shock is due to a higher cost of waiting – feeling dreadful about the coming shock.
This week in Science a team of researchers led by Greg Berns used fMRI to study how the brain works when people dread an upcoming shock (see abstract). They compared mild and extreme dreaders while making the shock choice. Adding a twist to the standard choice, subjects were to choose between an immediate but higher voltage shock or a later, milder shock. Some individuals dreaded the outcome so much that, when given a choice, they preferred to receive more voltage rather than wait.
So what about the mild dreaders versus the extreme dreaders? In their study, Burns et al. found that even if there was no choice, extreme dreaders had an increase rate of neural activity in the posterior elements of what has been previously identified as a cortical pain matrix. This is illustrated in the following figure from the article:
Caption: Effect of voltage and delay on the brain response to the shock itself.
Pain has been known to invoke a widespread network of brain regions, including the cingulate cortex. This is shown through a meta analysis of neuroimaging studies of pain and the cingulate cortex using the very useful Brede database by Finn Årup Nielsen.
Burns et al. conclude in their article:
In addition to suggesting a neurobiological substrate for the utility of dread, our results have implications for another assumption of utility theory: the origin of preferences. It seems likely that an individual's relative preference for waiting for something unpleasant derives from previous experience. In our experiment, participants presumably had well-established preferences for waiting, although it is unlikely that they had previous experience with foot shocks. We thus observed the construction of waiting preference in the specific context of foot shocks without any choices being offered. That the activity patterns in the brain regions associated with the pain experience correlate with subsequent choices offers strong evidence for the existence of intrinsic preferences. Although it is not clear how malleable these preferences are, their existence may have health implications for the way in which individuals deal with events that are known to be unpleasant—for example, going to the doctor for painful procedures. The neurobiological mechanisms governing dreading behavior may hold clues for both better pain management and improvements in public health.