Background Attractiveness is not just dependent on the vision but is often adjusted by other sensory cues Voices have been shown to influence a person’s perceived attractiveness Olfactory cues (smell) also play an important role in nonverbal communication A significant positive correlation found between the rated sexiness of a man’s body odor & his facial attractiveness to females
Background Olfactory cues Major histocompatibility complex - A set of molecules displayed on cell surfaces that are connected to our immune system responses recognition of "self" and "non-self" A man’s major histocompatibility complex will help decide how attractive his bodily odor is to females (They prefer those with a different MHC) Woman’s preference for the scent of some males has been shown to change with her menstrual cycle
Why was this investigation carried out? Until now only one study demonstrated any behavioural effects of olfactory cues in judgements of facial attractiveness. The investigators decided to conduct a psychophysical study to see if briefly presented olfactory cues can modulate visual judgements of facial attractiveness. To assess if cues with different hedonic value (pleasant v/s unpleasant) can enhance or reduce the perceived attractiveness of a face.
Aim To investigate whether olfactory cues can influence people’s judgments of facial attractiveness
Hypothesis A pleasant versus unpleasant odor can modulate female participants’ ratings of the perceived attractiveness of briefly presented male faces
Sample 16 female volunteers The University of Oxford Age 20 to 34 ‘Blind’ at beginning Completed a questionnaire ensure that they had a normal sense of smell, no history of olfactory dysfunction, & normal vision Confounding variables! Chose women because previous research has suggested that females may be more sensitive to the effects of olfactory cues than males
Materials 40 male faces for visual stimuli From a standardized database Extensively characterized for attractiveness & categorized into high, medium, & low attractiveness 20 faces from each of the high & low groups
4 odors (2 male & 2 non-male) & clean air 2 pleasant odors: geranium & male cologne ‘‘Gravity” 2 unpleasant odors: male body odor & rubber A custom-built computer-controlled olfactometer was used to deliver the odorants
Procedure/method Laboratory experiment Repeated measures design Subject to order effects (Counterbalancing) IV= Pleasant odors, unpleasant odors, neutral odors DV=Modulation of female participants’ ratings of the perceived attractiveness of male faces
Procedure/method 3 blocks of 40 random trials (each person completed 120 trials) Each face was randomly presented 3 times during each session Once with a pleasant odor Once with an unpleasant odor Once with a neutral odor (i.e., clean air)
Procedure/method Participant sat staring at a computer with their chins on a chin rest They were told to look at a fixation mark on the screen Quiet tone exhale Louder tone odor was released (inhale) They had to indicate if an odor had been released or not using the keyboard 1 second later one of the faces appeared for ½ second in the center of the screen As soon as the face disappeared the odor stopped and clean air was delivered. The screen then turned black
Procedure/method Then a 9-point rating scale appeared and the participants were to rate the perceived attractiveness of the face that they had just seen 1 (least attractive) to 9 (most attractive) As soon as they made their rating, clean air was delivered and the next trial started
Procedure/method At the end each participant was asked to smell the odors individually & to rate each odor on several different dimensions use a pen and paper Labeled Magnitude Scale (LMS) from 0-100. odor intensity odor pleasantness odor familiarity The order of presentation of the odors and the scales was randomized between participants
Label Magnitude Scale What is the difference between this and a Likert Scale? Between this and a forced choice?
Procedure/method In order to counterbalance the presentation of each face/odor combination, the entire set of 40 faces was divided into 4 groups of 10 faces each (5 high attractiveness & 5 low attractiveness) with close to the same mean attractiveness. Each group of faces was then presented with 1 different possible combination of pleasant– unpleasant odors, counterbalanced across participants. ABBA
Procedure/method So each participant rated 1. 10 faces presented with clean air, the geranium odor, & the body odor during the experiment. 2. 10 faces with clean air, the male perfume, & the rubber odor 3. 10 faces with clean air, geranium odor, & the rubber odor 4. 10 faces clean air, the male perfume, & the body odor. The same odor was never presented to participants on consecutive trials. The experiment lasted for approximately 50 min in total.
ACTIVITY Get into your groups and using the sheet as a guide, discuss the results and conclusions.
Results/Findings Faces significantly less attractive when presented with unpleasant odor than when presented with either a pleasant odor or with the neutral clean air Didn’t matter if the odor was body relevant There was no significant difference between pleasant versus neutral clean air
Discussion Adds to a growing list of studies: 1. Presence of olfactory cues can exert a small but significant influence on people’s judgments of a variety of non-olfactory stimulus attributes/qualities (Smell matters) 2. Presence of fragrance cues can influence people’s evaluation of job applicants Would be interesting to see what happens under more ecologically valid conditions
Ethics Ethical standards 1964 Declaration of Helsinki A set of ethical principles regarding human experimentation developed for the medical community by the World Medical Association (WMA)~ Widely regarded as the foundation of human research ethics Department of Experimental Psychology, University of Oxford
Evaluation Strengths Controlled Counterbalanced to control for order effects Replicable Weaknesses Generalization (population/sample) Demand characteristics Halo dumping Validity (ecological, construct)
Evaluation Were the effects due to a halo-dumping? When a certain characteristic (smell) is unavailable using the one of another sense to describe it. This can lead participants to ‘dump’ the values they could use So they describe a smell as sweet when it is really vanilla (sweet is for taste) In this case they might have been expressing their like or dislike of the odor on the facial attractiveness scale Possible as they only had one scale to use, so couldn’t separate their evaluations
Evaluation Demattè et al say no the participants in the study had to perform an odor detection task at the beginning of each trial, meaning that odor and visual information were responded to as 2 distinct and individuated ‘‘Attractiveness’’ is a clear, natural, & easy characteristic to consider when rating human faces, so it is unlikely that the participants had doubts concerning which variable they were supposed to rate in the task Are vision and smell easy to confound?