The Love Hormone and Memory for Faces

When you see an attractive face, a warm glow may ensue. When you see an ugly or threatening face, just the opposite occurs. Studies in animals have made it clear that a hormone from the pituitary gland, oxytocin, modulates such responses. In animals, oxytocin helps them decide whether to shun another animal or to approach for such purposes as socialization and mating. Oxytocin promotes approach behavior and suppresses avoidance.

If the same processes occur in humans (we use oxytocin too), then it should be reflected in how we react emotionally to others. Well, it does, and that is why it is sometimes called the “love hormone.” The best documentation for such action is that oxytocin is released in great amounts when a mother gives birth and increases the mother-infant bond. How robust this effect is in people is not clear.

Oxytocin could be important for remembering other people. In an experiment in Switzerland, men received a single nasal-spray dose of oxytocin and tested for their ability to recognize previously seen faces. The hormone improved recall of faces seen the day before, but had no effect on remembering non-social objects such as houses, landscapes, or sculptures. The study involved 44 male volunteers who were given three puffs of spray in each nostril of either oxytocin or a placebo. After a 40-minute delay to let the drug reach the brain, subjects were shown photos of 84 faces (half male, half female; 1/3 emotionally positive, 1/3 emotionally negative, and 1/3 neutral) and 84 images of inanimate objects for 3.5 seconds each. One day later, they were shown the same 84 pictures mixed randomly with other pictures they had not seen and asked to identify which photos they remembered and which were new from the previous day.

During the initial exposure (encoding) no differences were found in ratings for approachability (likeability) of either the faces or inanimate objects. Likewise, no oxytocin-related differences were seen for the emotional subcategories of positive, negative, or neutral, although everyone had more difficulty in remembering emotionally neutral faces. Gender of the faces did not seem to make much difference. Maybe this lack of effect was due to insufficient dosage (a single spray of three puffs may not be enough).

Where the drug effect was evident was in recognition memory of the faces. Oxytocin also increased the ability to realize that a new face had not been in the initial encoding group on the learning day.

Other studies have shown that oxytocin has a general pro-social effect, such as trust, for example.Take home message? One thought is the next time you want to attract someone, you might make yourself more memorable if you offered them some nasal spray laced with oxytocin. Of course that is too socially awkward. But one thing that is more practical is to take a few snorts of spray before going to a meeting or conference where you need to remember the new people you meet. Novartis already makes such a spray (Syntocinon). However, the drug’s medical use is to induce labor in pregnant women.

My second thought is there may something to the old saying about “love at first sight.” Certain faces may, for unknown reasons, cause a surge in endogenous secretion of oxytocin in the brain of the viewer and thus give that face a greater impact. Women knew all along the importance of having a memorable face; that’s why they wear makeup and fuss over their hair.

Source:

Rimmele, U. et al. 2009. Oxytocin makes a face in memory familiar. J. Neuroscience. 29 (1): 38-42.