Trust and Temperature

If I were a con artist, I'd get in the habit of buying people warm drinks. If that didn't work, I'd start conducting my con in warm rooms, or maybe move to a tropical region. Why? Because fleeting feelings of heat increase our willingness to trust strangers. That, at least, is the conclusion of a clever new paper from the Bargh lab, which measured the effect of temperature on interpersonal interactions. It's yet another reminder that even the most incidental bodily cues can impact our beliefs and behavior; the brain is an embodied machine. Here's the abstract:

Trust lies at the heart of person perception and interpersonal decision making. In two studies, we investigated physical temperature as one factor that can influence human trust behavior, and the insula as a possible neural substrate. Participants briefly touched either a cold or warm pack, and then played an economic trust game. Those primed with cold invested less with an anonymous partner, revealing lesser interpersonal trust, as compared to those who touched a warm pack. In Study 2, we examined neural activity during trust-related processes after a temperature manipulation using functional magnetic resonance imaging. The left-anterior insular region activated more strongly than baseline only when the trust decision was preceded by touching a cold pack, and not a warm pack. In addition, greater activation within bilateral insula was identified during the decision phase followed by a cold manipulation, contrasted to warm. These results suggest that the insula may be a key shared neural substrate that mediates the influence of temperature on trust processes.

In addition to extending the literature on embodied cognition, this paper also helps clarify the role of the insula. One of my favorite recent papers on the insula was this study of cigarette smokers: It turned out that smokers with a damaged insula were 136 times more likely to quit than control subjects. The reason, according to the scientists, returns us to the function of the insula, which is to monitor the intersection of flesh and feeling. It detects the bodily changes associated with smoking - the escalated pulse, the slow inhalation, the slight nicotine rush - and combines those physical sensations with the idea of a cigarette. Over time, these bodily cues lead to the development of an addiction: When we crave a cigarette what we are actually craving is this sequence of fleshy feelings. Because people without a functioning insula can't fully experience these cues - they are disconnected from their bodily - they never develop the same physical need for nicotine. It's easy to quit.

The latest paper on the insula and trust extends this concept to interpersonal decisions. Once again, we see the insula mediating the relationship between changes in the body - in this case, the difference is temperature - and our ensuing decisions. We like to see ourselves as Promethean creatures, mostly liberated from this sack of meat we have to carry around for support. (John Updike, as usual, said it best: "We think we are what we think when in truth we are upright bags of tripe.") But what the insula and these studies of embodied cognition demonstrate is that our mind is impossibly intertwined with carnal changes we can't explain or comprehend. So the next time someone asks you for money, ask yourself: How warm am I? What is my insula thinking?