Your Brain and You

Imagine you’re a prehistoric heterosexual man who’s going into battle tomorrow. The thought that there’s a fair chance of your dying might so completely occupy your mind that you’d be uninterested in anything save, perhaps, sharpening your spear.

On the other hand, your attitude might be that if you’re going to be checking out tomorrow, you’d like to have one last time with a woman tonight.

We are more likely to be descendants of the second type of man than the first. So, we might expect that there would be a tendency among men for thoughts of their own death to raise their susceptibility to sexual arousal.

In contrast, women who were more erotically motivated when they believed their own death might be just around the corner would not generally have produced more offspring than their less susceptible sisters. So, there is no reason to expect that making thoughts of death salient should affect sexual preparedness in women.

These ideas have recently been tested in two studies by Omri Gillath and colleagues. Of course, they didn’t send anybody into battle. Instead, they used two methods – one conscious, one not – to make the idea of death salient.

In the first study, one group of participants wrote responses to questions about the emotions they had while thinking about their own death and events related to it. Another group responded to similarly phrased questions about dental pain. The point of this contrast was to distinguish whether an arousal (if found) was specific to death, or whether it was due more generally to dwelling on unpleasant topics.

After responding to the questions, participants were shown either five sexual pictures (naked women for men, naked men, for women) or five non-sexual pictures (sports cars for men, luxury houses for women). Previous studies had found that all the pictures were about equal for their respective groups on overall perceived attractiveness. Participants had all self-identified as heterosexual. They had five minutes to carefully examine their set of five pictures.

Participants were each connected to a device that measured their heart rate. The key result was that the men who answered the questions about death and viewed erotic pictures had a significantly higher average heart rate during the picture viewing than any other group. That means that, on average, they had a higher rate than other men who saw the same pictures, but had answered questions about dental pain. They also had a higher rate than other men who had answered questions about death, but then saw non-sexual pictures. And they had a higher rate than women who answered either question and viewed either pictures of naked men or non-sexual pictures.

In the second study, the death/pain saliency difference was induced by flashing the word “dead” (for half the participants) or the word “pain” (for the other half) before each item in a series of pictures. The presentation of the words was very brief (22 thousands of a second) and came between masks (strings of four X s). With the masks, that’s too short to recognize the word. The pictures either contained a person or did not. Half of the pictures that contained a person were sexual, half were not. Pictures remained visible until the participant responded.

The response was to move a lever if, but only if, the picture contained a person. The movement was either pulling the lever toward oneself, or pushing it away. There were 40 consecutive opportunities for pulling, and 40 for pushing; half of participants started with pulling, half started with pushing.

The logic of this experiment depends on a connection previously established by Chen and Bargh (1999) between rapidity of certain responses and the value of what is being responded to. Pulling brings things closer to you, and if what’s before your mind is something you like, then that will speed the pulling (relative to pulling in response to something you’d ordinarily try to avoid, or something toward which you are neutral).

The reasoning, then, is that those who had a higher degree of sexual preparedness should pull faster in response to erotic materials than those who were not so highly prepared. Gillath and colleagues hypothesized that participants who received the brief exposure to “dead” and then saw an erotic picture should be faster pullers than those who received a brief exposure to “pain” before an erotic picture.

And that is what they found – for men. There was no such result for women. Nor did the brief exposure to “dead” result in faster pulling after being presented with non-sexual pictures; the faster reaction times depended on both the exposure to “dead” and the sexual nature of the following picture.

These two studies are certainly interesting in relation to the evolutionary thinking that led them to be undertaken. But I also find them fascinating in relation to a more general point. The second study provides evidence that our brains can (a) make a distinction (between pain and death) and (b) relate it to another difference (sexual vs. non-sexual material) completely unconsciously and extremely rapidly. And the first study, although done at a much slower time scale and with consciousness of the materials used to manipulate mood (i.e., the writing about death vs. pain), showed an effect on heart rate, which is not something that was under participants’ control. The brain processes of which we are unaware (except when revealed in studies like these) are amazing indeed.

[O. Gillath, M. J. Landau, E. Selcuk and J. L. Goldenberg (2011) “Effects of low survivability cues and participant sex on physiological and behavioral responses to sexual stimuli”, Journal of Experimental Social Psychology 47:1219-1224. The previous study mentioned in the discussion of Study 2 is M. Chen and J. A. Bargh (1999) “Consequences of automatic evaluation: Immediate behavioral dispositions to approach or avoid the stimulus”, Personality and Social Psychology Bulletin 25:215-224. ]