Chapter 3: Methodology
3.4. Sampling, Recruitment and Data Collection
3.4.1. The Stimuli
Sampling and Recruitment
A convenience and purposive sampling method was used in this study. According to Henry (1998) convenience sampling is a type of nonprobability sampling which impedes the generalizability of a study as participants are recruited from subpopulations most readily available to the researcher and not randomly selected from the general population. The use of non-probability convenience sampling methods does introduce sample bias as the sample readily available (i.e. the student population) belongs to a specific subgroup of the population which may differ from the general population on some characteristic attributes (Henry, 1998).
The stimuli sample in this research was recruited from the undergraduate male population of the Pietermaritzburg UKZN campus. The research conducted required that only androgen based chemo-signals be utilised as to minimise the complexity of the study, therefore, only adult men were required to constitute the stimulus. Furthermore, only two race groups were recruited for this sample as Van Beek (1992) suggests that race and culture are intrinsically
linked and food often has cultural significance which would affect BO. Thus, because sex and race were criteria on which recruitment was based, the sampling was purposive.
The stimuli participants were approached whilst at leisure on the main campus lawns, these individuals were given a brief explanation of the purpose of the study and asked if willing to attend an appointment at the most convenient time for them the following day. Of the approximate 40 individuals who were approached, 29 attended their appointment. Of those 29 participants, six individuals dropped out, leaving 23 participants who completed the study adequately. Of the 23, six were selected for the stimuli, based on race matching (i.e. three Black and three White males) and obvious adherence to the required rules. Participants were offered a free t-shirt as an incentive for their participation. Participants who did not adhere to the rules were not disadvantaged in any way regarding the incentive. The stimulus t-shirts were kept in a freezer until the main phase of data collection. After the initial collection of main data, the t-shirts had begun to lose their scent. Hence, the t-shirts were washed without detergent and re-worn by the same participants who were contacted via sms and offered a further incentive of R20.00.
Materials
The stimuli sample in this study was made up of a pheromone scent stimulus (SS) as well as a visual stimulus (VS), both of which needed to come from the male population specifically.
For the pheromone stimulus worn t-shirts were used. Previous studies have used a similar technique for obtaining the chemo-signal found in sweat (Gangestad, et al., 2005; Miller &
Maner, 2010; Singh & Bronstad, 2001).
All stimuli participants were given an information sheet explaining the aspect of the study they were participating in, as well as a consent form which required consent for participation in each area of the study considered challenging or sensitive, such as wearing a t-shirt for two consecutive nights, having their photograph taken and supplying their contact information.
Each stimuli participant was also given a short questionnaire in which the participants indicated their race, sex and age, as well as contact information in case reminders to return the t-shirts were necessary. A copy of the information sheet and consent form can be found in appendix C. The short questionnaire filled out by the stimuli sample appeared as follows.
To create the pheromone stimulus, 30 identical white cotton t-shirts were used, all the t-shirts were same size (XL) to reduce size bias in the second phase of data collection. Each of the t- shirts was sealed with a bar of unscented soap in a large reseal-able Ziploc bag.
Participants were explained a list of rules on how to wear the t-shirts without contaminating them with other odours. This was to minimise the risk of extraneous odours from modifying the scent that would thus influence respondent’s rankings of preference in the second phase of data collection.
Instructions for wearing the t-shirts:
1. Please sleep in the given t-shirts for the next two consecutive nights.
2. Please do not wash the t-shirts.
3. Please will you wash your bed linen on the day prior to participating 4. Please wash with unscented soap before wearing the t-shirts
5. Please do not wear any deodorant, perfume or scented talc powder before wearing the t-shirts.
6. Please do not eat any of the following strong foods on the nights you are given to wear the t-shirts: garlic, chilli, cabbage, cheese, onion, and asparagus.
7. Please do not drink any alcohol before or whilst wearing the t-shirt STIMULUS PARTICIPANTS
Name: ________________________________
Age: __________________
Ethnicity: Black_______ White_______
Contact Number_______________________
Email Address__________________________________________
Figure 4: Example of stimuli participant questionnaire
8. Please do not smoke any tobacco products whilst wearing the t-shirt
9. Please do not use any recreational drugs before or whilst wearing the t-shirt 10. Please do not engage in any sexual activity whilst wearing the t-shirt
11. Please refrain from sleeping in the same bed as another person whilst wearing the t- shirt
12. Please will you place the t-shirt in the Ziploc® bag after wearing it on each night and seal the bag.
13. Please will you return the t-shirt in the sealed Ziploc® bag to the psychology masters room by 10:00am on the day following the second night.
As an incentive, all the t-shirt wearers were given a black t-shirt to keep. A R20 incentive was offered to those selected students who were later asked to re-wear the t-shirts. The t- shirts once returned were kept in an empty freezer.
A photograph of each of the participants’ faces was taken using a Canon EOS M camera.
Each t-shirt had a unique four-digit numeric code written in black permanent marker on the inside collar, which corresponded to another unique three-digit code given to each photograph. This was saved in a password-protected database to ensure the confidentiality of the participants and to ensure the obscurity of the scent and image connection. All six of the selected stimuli participants were heterosexual.
Procedure
Once the male stimuli participants were recruited and given an appointment time they arrived at the psychology lab (room 25) in the psychology building at the UKZN Pietermaritzburg campus the following day. Interestingly none of the participants arrived at their allotted time and a few non-recruited participants turned up, these individuals had been told about the study from their friends. Once informed consent was obtained from each participant, they were asked to fill out a brief questionnaire (Appendix D) indicating demographic information and then were taken one at a time into a connecting room to pose individually for the photograph. All photographs were taken with the same camera and background and at the same distance from the participant. All the participants were asked to look straight ahead without smiling, as smiling tends to affect attractiveness judgments (Otta, Abrosio, &
Hoshino, 1996). Photographs were taken of the participants faces from the top of the shoulders. The photographs were also all taken in greyscale to reduce the effects that skin tone and condition may have on attractiveness judgements (Penton-Voak, et al., 1999).
Furthermore, the photographs were taken in the same room, in artificial light, thus eliminating any confounding variables that time of day might have had. Participants were all given identical white cotton t-shirts and a fragrance-free bar of soap in a sealed Ziploc® bag and asked to return just the t-shirt in the Ziploc® bag in two consecutive days’ time to the masters’ room in the psychology building at the Pietermaritzburg campus. Exactly 23 of the t-shirts were returned and all those participants were given a black t-shirt as a thank-you gift for their participation. From the 23 t-shirts collected, six were chosen for the final phase of data collection. Those shirts that were noticeably contaminated by other smells, such as cigarette smoke, deodorant or soap other than the one given or food, were eliminated from the pool.
After the initial second phase of data collection, deterioration of the SS had occurred as the scent on the t-shirts had been altered (Gravetter & Forzano, 2009). Therefore, it was necessary to re-acquire the scent of BO from the stimuli participants. The t-shirts were washed, without detergent and then given back to those six participants to re-wear. The participants were contacted via sms and email using the contact details that they had provided. All of the six participants agreed verbally to participate further in the study. The participants were once again explained the purpose and rules of the study and verbally agreed to participate again. The participants collected the t-shirts from the masters’ room and returned them two days later. For their further participation, these individuals received an incentive of R20.00.
All researchers involved were knowledgeable of the study procedure and could answer any questions that participants may have had.