Post by Anastasia Sares

What's the science?

Persuasive messages surround us every day, and they often make appeals to our emotions in order to change our behavior. However, we are not always influenced by emotional persuasion and often need to regulate our emotions to control our response. The brain regions involved in emotional reactions, emotional regulation, and decision making are well known. However, whether these brain regions can predict our response to a persuasive message and how these regions work together, remains unclear. This week in the Journal of Neuroscience, Doré and colleagues tested how different brain areas work together in response to persuasive messages in order to influence our decision-making, in the context of an anti-smoking campaign.

How did they do it?

The data used in this study came from two sources: 1) An MRI (magnetic resonance imaging) experiment in which smokers were shown anti-smoking ads with a number of different graphic images. The authors measured the neural response to each image (based on the blood-oxygen-level-dependent, or BOLD signal), and also asked each participant to rate how much each image made them want to quit. 2) An email campaign, with the same ads and images as the MRI study, sent out to likely smokers. Each email had only one of the images, but the rest of the ad was the same for everyone. The authors measured the click-through rate for each image - in other words, how many times a person who opened the email would proceed to click on a link leading to a website with material to help them quit.

The authors decided to build and test a model of the persuasion process using information based on past research. The amygdala reacts to negative, emotional images like the ones they used, while the ventro-medial prefrontal cortex (vmPFC) integrates different kinds of information before making a decision, and is involved in self-control. A previous meta-analysis (linked here), has also shown a diffuse pattern of brain areas involved in emotion regulation, which they hypothesized would be involved in regulating emotional responses. Given this information, they measured whether successful persuasion of a participant (i.e. participant saying the ad made them want to quit smoking, or click-throughs) could be predicted by brain activity within these regions and whether responses were modulated by activity in the previously defined emotion-regulation pattern. They added regions to the analysis one by one to evaluate their contributions (using techniques including Bayesian statistics and multilevel modeling).

What did they find?

The study yielded three main findings. First, they found that anti-smoking images that produced the most activity in the amygdala were also more likely to make participants say that they want to quit smoking. Not only that, but the images with the most amygdala activity also had higher click-through rates in the email ad campaign. This highlighted the effect of raw emotion on decision-making. Second, the relationship between amygdala activity and decision making was mediated by activity in the vmPFC. In other words, the amygdala seemed to be communicating with the vmPFC, which would then determine the response. This highlighted the vmPFC’s role as an integrator. Lastly, expression of the brain pattern involved in emotional regulation (previously defined in a meta-analysis) dampened the emotion-driven response to an ad, suggesting that this network plays a key role in regulating emotional responses to persuasive stimuli.