Two Key Studies of Pheromones & Their Effect on Behaviour: Zhou et al. (2014) & Hare et al. (2017) (SL IB Psychology)

Aim: To investigate the idea that androstadienone (AND) and estratetraenol (EST) may function as human pheromones in terms of sexual attraction.

Participants: 24 adult heterosexual males; 24 adult heterosexual females; 24 adult homosexual males and 24 adult bisexual or homosexual females. 

Procedure: The participants were exposed to either AND, EST or a placebo over the course of three days of testing (this was done via mixing the AND or EST with cloves in a jar which the participants then smelt). 
The participants watched a series of figures walking, using dots of lights at specific points on the figure e.g. the head, the pelvis. This was a virtual rendering of the action of the human body in motion with no gender markers on the figures i.e. they were presented as neither male nor female. They were shown each point-light walking figure for 0.5 seconds and then they had to say whether the figure was male or female.

Results: Heterosexual males made more judgments that the walker was female when they had been exposed to EST; heterosexual females made more judgments that the walker was male when they had been exposed to AND; homosexual males made more judgments that the walker was male when exposed to AND. 
In essence, heterosexual females and homosexual males showed a similar pattern of results, attributing maleness to figures when they had been exposed to AND. The findings for bisexual or homosexual females were less clear-cut and did not point to any definite conclusion.

Conclusion: Pheromones may be linked to how males and females perceive gender according to their own sexual orientation.

Evaluation of Zhou et al. (2014)

Strengths

• The researchers used a standardised procedure e.g. the same point-light figures were viewed across the conditions which ensures a reliable measure of control
• Using point-light figures rather than photographs of real human beings helps to eliminate the possible confounding variable of individual differences regarding who/what is attractive

Weaknesses

• The use of synthetic AND and EST does not reflect how these steroids are secreted in real-life situations which impairs the external validity of the study
• The task lacks ecological validity as it was artificial in nature and does not consider other variables that may result in judgements pertaining to masculinity or femininity

Key terms:

• AND 
• EST 
• Point-light figure

Aim: To investigate whether AND and EST play a role in the perception of gender and level of attractiveness of the opposite sex.

Participants: 94 (51 female; 43 male) white, heterosexual adults (mean age = 24 years) from the University of Western Australia.

Procedure: The participants took part in two tasks on a computer while being exposed to the scent of either AND or EST via a cotton ball taped underneath their nose. In the experimental condition the scent was disguised with clove oil. In the control condition only clove oil was applied to the cotton ball. 
This study used a repeated measures, double-blind design and employed counterbalancing i.e. half of the participants experienced the experimental condition followed by the control condition and the other half experienced the control condition followed by the experimental condition.

For task 1, the participants were shown 5 images of morphed gender-neutral faces (the blending male and female faces together) and were asked to identify the gender of each face. For task 2 the participants were shown opposite-sex faces (all Caucasian, with only the hairline and face showing). They were asked to rate the level of attractiveness of each photo and the likelihood of each person shown being unfaithful using a rating scale from 1-10 (10 indicating a high level of attraction and a strong likelihood that the person would be unfaithful). 

Results: The research was inconclusive: the researchers found no evidence that AND or EST affected gender perception or attractiveness rating or unfaithfulness rating.

Conclusion: AND and EST may not function as human pheromones.

Evaluation of Hare et al. (2017)

Strengths

• This use of a repeated measures design increases the validity of the findings as it involves each participant being compared with their own performance across conditions
• The use of morphed gender faces helps to ensure that no gender markers were present to influence the decision-making of the participants

Weaknesses

• Providing a rating of morphed faces shown on a computer is not something that people routinely do as part of everyday life, which makes the study low in external validity.
• Using only images of Caucasian faces is a source of bias in the study as some of the participants may be more attracted to people who are not of white ethnic origin 

Key terms:

• AND
• EST
• Counterbalancing