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Friday, January 23, 2009

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.


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

Wednesday, January 14, 2009

Talking Makes It Memorable

Students learn better when they can discuss test items with their peers. A group of professors at University of Colorado, Boulder, reported a study in which they tested the value of allowing peer discussion of questions during lecture. To break up the monotony of traditional lecture in a genetics course, the lecture was periodically interrupted with a paired set of similar multiple-choice questions (Q1 and Q2) for any given concept was asked back to back. For each question, each student voted for the correct answer with a "clicker," and tallies of votes were automatically posted on the instructors podium computer. After the vote on Q1, students were allowed to discuss possible answers (without being told what the right answer was) and then allowed to vote again. Then, they were asked a second question on the same concept (Q2) and voted without discussion.

Performance results were markedly enhanced on the second vote on Q1. For example, pooled over 16 sets of questions, the average correct response to Q1 without discussion was 52%. But 92% got the question right after they were allowed to discuss it with peers (usually 3-4 classmates). Of this same group, 90% then got Q2 right.

Gains were also seen in the group the gave the wrong vote the first time they saw Q1 (48%). Of these, 42% got the answer correct after they discussed it with peers and 77% got Q2 right. Of those who missed Q1, even after discussion, 44% got Q2 right. This indicates that the understanding gained from discussing Q1 helped them with Q2.

The advantage seen here of discussion is primarily one of improved understanding, not necessarily improved memory. But memory should also be improved because peer discussion engages students in thinking, and thinking promotes consolidation. The sound feedback from talking also reinforces memory. Students recognized a memory benefit, as exemplified in the comment "the answer almost sticks better (italics mine) because we talked through it instead of just hearing the answer." What I would like to have seen is a controlled study of two classes, one that got their lecture interrupted with questions in this way and another class that did not, with a final exam given to both groups in which half the questions were the same as those used in class and half that were new but related.


Smith, M. K. et al. 2009. Why peer discussion improves student performance on in-class concept questions. Science. 323: 122-124.

Friday, January 02, 2009

Caffeine or Nap: Which Helps Memory?

Caffeine gets our brain pumped up. We are more alert and perhaps should remember things better. Naps have recently been found to help the memory consolidation process. Until now, nobody has made a direct comparison of these two factors in the same people under identical conditions. But Sara Mednick and her colleagues at the University of California, San Diego, now report some helpful findings.
They tested caffeine in a single dose of 200 mg (roughly equivalent to 2-3 cups of coffee) and compared with an episode of napping (60-90 min) or placebo on the effects on performance on three types of memory tasks. For verbal memory, they tested recall and recognition memory of word lists 7 hours after learning, with an intervening nap, caffeine dose, or placebo. In addition, they conducted memory tests for a finger tap and texture discrimination task.They also conducted short-term memory on a different set of words after the first experiment.
Compared with either caffeine or placebo, naps were more effective in the word recall test, both in the consolidation test and in the short-term memory condition. Caffeine actually impaired word recall in the short-term memory task, even though the caffeine had been given some seven hours earlier. Naps also improved recognition memory in the consolidation test and recall of the texture discrimination learning. For the finger-tap learning, naps were ineffective and caffeine markedly impaired performance. The caffeine group did feel less sleepy in the late afternoon immediately prior to the memory testing, but that did not help their memory performance.
What I take from this is that the morning coffee may help you awaken, but don’t count on it to improve your memory. Other research does show that caffeine enhances mood and alertness, reaction times and speed, but don’t count on it to help your memory for things you learn that day. Note to students: all-night study sessions are a bad idea for lots of reasons and probably made much worse by drinking lots of coffee. Note to bosses: letting workers take an afternoon snooze might be a good idea.

Mednick, S. C. et al. 2008. Comparing the benefits of caffeine, naps, and placebo on verb al, motor and perceptual memory. Behavioural Brain Research. 193: 79-86.