Pheromones and their role as aphrodisiacs: A review

Interpersonal Chemistry: What Is It, How Does It Emerge, and How Does It Operate?

Although chemistry is a well-known, sought-after interpersonal phenomenon, it has remained relatively unexplored in the psychological literature. The purpose of this article is to begin articulating a theoretically grounded and precise definition of interpersonal chemistry. To that end, we propose a conceptual model of interpersonal chemistry centered around the notion that when two or more individuals experience chemistry with one another, they experience their interaction as something more than the sum of their separate contributions. Our model stipulates that chemistry encompasses both behavior (i.e., what chemistry "looks like") and its perception (i.e., what it "feels like"). The behavior involves interaction sequences in which synchronicity is high and in which people's goals are expressed and responded to in supportive and encouraging ways. The perception of chemistry includes cognitive (i.e., perception of shared identity), affective (i.e., positive affect and attraction), and behavioral (i.e., perceived goal-relevant coordination) components. We review existing research on chemistry as well as supporting evidence from relevant topics (e.g., attraction, similarity, perceived partner responsiveness, synchrony) that inform and support this model. We hope that this conceptual model stimulates research to identify the circumstances in which chemistry arises and the processes by which it affects individuals, their interactions, and their relationships.

Prior exposure to Hedione, a model of pheromone, does not affect female ratings of male facial attractiveness or likeability

The existence of pheromones in humans is controversial, partly because of definitional difficulties and partly because of the question of possible chemical substances. The synthetic compound Methyl dihydrojasmonate (Hedione) is potent to bind to vomeronasal-type 1 receptors (VN1R1s) and activate limbic areas of the brain in a sex-specific manner. However, one of the most important definitional points for a human pheromone effect has not yet been investigated, i.e., whether smelling Hedione, a model of pheromone, has a behavioral effect. We tested in females whether Hedione leads to altered perception of male social stimuli. Each of the included women were sensitive to Hedione and were tested around the time of ovulation in three consecutive sessions, during each they were exposed to either Hedione or Phenylethyl alcohol or Odorless air. We measured the speed of male face recognition (implicit priming task) and collected ratings of facial attractiveness and likeability of men (explicit task). Only about half of the women tested were sensitive to Hedione. Those women did not show any effect of Hedione exposure in the implicit priming task and moderate, but non-significant effects in the explicit task. We therefore assume that Hedione is not a potent model of pheromone in humans and this observation may be due to the fact that the artificially produced substance is not suited for signaling the proximity of other humans. Furthermore, the high rate of Hedione-specific anosmia leads to the hypothesis that a substantial proportion of individuals has a poor V1NR1 receptor expression.

Putative sex-specific human pheromones do not affect gender perception, attractiveness ratings or unfaithfulness judgements of opposite sex faces

Debate continues over the existence of human sex pheromones. Two substances, androstadienone (AND) and estratetraenol (EST), were recently reported to signal male and female gender, respectively, potentially qualifying them as human sex pheromones. If AND and EST truly signal gender, then they should affect reproductively relevant behaviours such as mate perception. To test this hypothesis, heterosexual, Caucasian human participants completed two computer-based tasks twice, on two consecutive days, exposed to a control scent on one day and a putative pheromone (AND or EST) on the other. In the first task, 46 participants (24 male, 22 female) indicated the gender (male or female) of five gender-neutral facial morphs. Exposure to AND or EST had no effect on gender perception. In the second task, 94 participants (43 male, 51 female) rated photographs of opposite-sex faces for attractiveness and probable sexual unfaithfulness. Exposure to the putative pheromones had no effect on either attractiveness or unfaithfulness ratings. These results are consistent with those of other experimental studies and reviews that suggest AND and EST are unlikely to be human pheromones. The double-blind nature of the current study lends increased support to this conclusion. If human sex pheromones affect our judgements of gender, attractiveness or unfaithfulness from faces, they are unlikely to be AND or EST.

Is the use of plants in Jordanian folk medicine for the treatment of male sexual dysfunction scientifically based? Review of in vitro and in vivo human and animal studies

Male sexual dysfunction is a serious problem which has an impact on the quality of life. In Jordanian folk medicine, 56 plant species were reported to be used by males to improve sexual potency and as aphrodisiacs. The aim of this study was to search for scientific evidence justifying their folk use. Of the 15 studied plants, only five were found to enhance spermatogenesis. The other 10 were reported to decrease spermatogenesis at least by one study. The majority of the studied plants possessed a protective effect on testis in different in vivo models as well as antioxidant activities. The effect of these plants on steroidogenesis and the hypothalamic-gonadal axis was also reviewed. The effect of only five plants was studied on sexual behaviour enhancement and three of them were active. Three of the four studied plants enhanced erection. The mechanism of action of active constituents isolated from the studied plants was also investigated. In conclusion, many plants used in Jordanian folk medicine decreased or had no effect on spermatogenesis in animal models. These plants have antioxidant and/or adaptogenic effects, and this may result in a beneficial action on male reproductive system.