Oxytocin, a substance secreted by certain brain cells, plays an important role in the social behavior of animals, including humans. Experiments have shown that under the influence of oxytocin, men become more sensitive to positive words associated with relationships between people, but oxytocin does not affect the perception of words belonging to other semantic categories.
We have already written about the role of the neuropeptide oxytocin in the regulation of sexual and social behavior in animals and humans (Genes control behavior, and behavior controls genes). Oxytocin and related peptides are known to regulate female sexual behavior, oviposition or childbirth, lactation, attachment to children and sexual partner. Oxytocin also suppresses the activity of the amygdala (amygdala), a part of the brain involved in the processing of socially significant information and regulating feelings of anxiety and fear (most likely, this is why males become calmer and more courageous after mating).
The effect of oxytocin on the human psyche is studied only on men. This is easy to understand, given that in medical practice oxytocin is used to stimulate uterine contractions during childbirth. It turned out that oxytocin makes men more trusting, improves the ability to understand the mood of other people by facial expressions and encourages more eye contact (see the above note for details).
These studies began relatively recently, but enough data has already been accumulated to proceed to attempts at generalization. Is it possible to reduce the various psychological effects caused by oxytocin to some common denominator? What unites them? It has been suggested that the general direction of the action of oxytocin on the male psyche is a selective increase in sensitivity (susceptibility) to socially significant signals that have a «positive» color. An alternative possibility is that oxytocin heightens susceptibility to any positive stimuli, not just socially significant ones.
With the help of an elegant experiment, Australian and German psychologists were able to convincingly confirm the first of two hypotheses. The study involved 44 male volunteers. They were randomly divided into two groups — experimental and control. Oxytocin was dripped into the nose first, water (placebo) was the second. Immediately prior to this, all participants underwent a special mood test (see: PANAS). 45 minutes after pernasal administration of oxytocin or placebo, they retested. This allowed the researchers to establish that oxytocin did not improve or worsen the mood of the subjects.
Then the main stage of the experiment began. Each participant had to determine as quickly as possible whether the word gradually appearing on the computer screen was “positive” or “negative”. The researchers selected for the experiment 60 words belonging to five semantic categories, and in each category there were six “positive” words and the same number of “negative” ones. The categories were as follows:
1) human relations (for example, love / hate),
2) sex (kiss/brothel),
3) danger or safety (security/threat),
4) joy or sadness (satisfied / sad),
5) other positive and negative words (for example, virtue/crime).
Each participant had to «guess» all 60 words. At first, a black rectangle was shown on the screen. The subject himself began testing by pressing the space bar. After that, the black rectangle gradually «dissolved» within 8 seconds. From underneath, pixel by pixel, a hidden word emerged. The subject had to determine as quickly as possible whether the word was positive or negative and press the corresponding button.
The results confirmed the hypothesis that oxytocin selectively heightens the perception of positive socially significant stimuli — and no others. Men who were injected with oxytocin were significantly faster (about 0,2 seconds on average) to recognize “positive” words from the first two semantic categories (sex and relationships), but oxytocin did not affect the recognition rate of all other words.
The result remained statistically significant after the introduction of the necessary corrections for the length of words and the frequency of their occurrence. Differences in the mood of the subjects, as well as their personal opinion about the real or imagined side effects of the administration of oxytocin (this was determined by questioning a day after the experiment) did not affect the speed of word recognition. The introduction of oxytocin does not seem to have any conscious effects (I confess in secret, I tried to put some oxytocin in my nose, and did not feel anything special).
Thus, oxytocin makes men more receptive to signals and stimuli that carry information important for establishing good relationships (for example, friendships or sexual relations) with other people. Most likely, it affects women in the same way — after all, in other mammals, oxytocin regulates the attachment of a female to her children, and in monogamous species, also to a sexual partner.
A source: Christian Unkelbach, Adam J. Guastella, and Joseph P. Forgas. Oxytocin Selectively Facilitates Recognition of Positive Sex and Relationship Words // Psychological science. 2008. V. 19. P. 1092–1094.