AS Psych: Hassett et al. (monkey toy preferences)
Psychology Being Investigated
1. There are sex difference between males and females, caused by differences in the brain and hormones, which impact behavior
2. Traditional views suggest toy preferences are due to socialization, the process of learning to behave in a socially acceptable manner
– Socialization process is determined by cultural bias and stereotype, but it is overly simplified to believe members of a gender share similar gender characteristics
3. Play is one behavior in which differences can be seen between males and females
– Boys tend to engage in aggressive/active play (e.g. playing with nerf guns and toy cars) BUT girls tend to engage in nurturing play (e.g. dolls, farmhouse, cooking)
4. Prenatal hormone exposure, e.g. to androgens, is known to influence children’s toy preferences
Background
It is difficult to conduct studies on children’s development
– Unethical to expose or limit hormone exposure (for developing fetuses) or control child’s developmental environment
– Difficult to eliminate uncontrolled variables (e.g. exact amount of hormonal exposure/extent of gender-related socialization
But higher primates are closely genetically related (males have testosterone, females oestrogen) to humans and have similar behaviors (males ‘rough-and-tumble’ and females interest in infants)
– Can be used as a model to understand toy preference differences/determine if sex differences are due to biological > social differences
Hassett et al.
– Some girls have a genetic condition that causes increase in androgens (including testosterone) called congenital adrenal hyperplasia (CAH)
– Makes them prefer “boys” toys rather than “female appropriate” toys
Alexander & Hines (2002)
– Looked at nonhuman primates’ (vervet monkeys) interaction with human toys
– However, monkeys were NOT presented with toys (male + female-type) simultaneously BUT rather, individually (i.e. presented male-type toy first, then female)
– Therefore, measured willingness to play NOT preference
– Findings: male vervets preferred masculine toys more than female, but males preferred all toys more than female vervets → not conclusive
Aim
1. To investigate if toy preferences in monkeys resemble those in human children, in order to test if sex differences in toy choice is biologically determined by sex.
Method
Research Method: Field experiment
Research Design: Independent measures
IV: Sex, male/female
DV: Toy preference
Sampling technique: Opportunity
Sample
– 82 rhesus monkeys
– Housed at Yerkes primate research station (USA)
– Lived in natal groups as part of a wider group of 135 primates for 25+ years
– 21 male, 61 female (potential participants, P)
– 14 received hormone treatments, 39 were young infants (cannot be reliably identified) → NOT used!
– final: 11 male, 23 female used for analysis
Housing
– Each natal group housed in a 25 x 25 meter outdoor area
– Had access to a temperature controlled indoor environment
– Water was available
– Given standard monkey feed twice daily + additional fruit and vegetables once daily
Procedure
– 7 trials for each social group
– 25 mins
– Observed using 2 video cameras
– Each trial began with all monkeys in the group indoors
– 1 plush toy + wheeled toy placed 10 meters apart in outdoor enclosure → counterbalanced between left and right positions on each trial
– After each trial, toys removed + video tape analyzed by 2 observers working together to achieve a consensus
1) Identified each animal interacting with a toy
2) Coded specific activities directed towards toys with a behavioral checklist (frequency)
3) Exact time activity occurred (duration)
Analysis of data
– Each animal can participate in a number of different activities/behaviors across different trials
– Records for each behavior of each animal converted into overall average frequency + duration
– P who had <5 total recorded behaviors (across 7 trials) were not used for analysis
Results
Very few monkeys interacted with the toys for longer than a few seconds and longer periods of time
Frequency
– Male monkeys preferred wheeled toys > plush toys
– Female monkeys showed no significant preference for plush toys or wheeled toys
– Male vs Female: no significant difference in terms of wheeled toy play, but males interacted significantly less with plush toys than females did
Duration
– Males interacted for greater total time with wheeled (4.76 mins) > plush toys (0.53 mins)
– Females showed no significant preference for plush or wheeled toys (both 1min+)
Magnitude of Preference for toys*
– Significant sex difference
– Males significantly higher preference for masculine-type (wheeled) toys than female for plush toys
Conclusion
1. Like boys, male monkeys have a strong preference for masculine-type toys (ones with wheels) and like girls, female monkeys are more variable in toy preferences
2. Since these preferences develop in the absence of socialization, findings support a biological explanation for toy preferences (in monkeys only hormonal differences are responsible for development)
Ethical Issues
Protection from Harm – one toy was destroyed; this may have been a playful act or an indication of distress
Otherwise, study conducted following ethical guidelines (USA) + approved by Emory University Ethical Committee
✔ P received regular and appropriated food + had constant access to water
✔ Ethically housed: family groups, large enclosure, indoor + outdoor area
✔ Interaction with toys suggest their novelty was not distressing
✔ Observation was done using a camera so it was not distressing
Application to Daily Life
– Results of this study can be used to consider male and female toy preferences when purchasing toys for children
*Males: (Total frequency (TF)+ duration (TD) wheeled) – (TF + TD plush)
*Females: (TF + TD plush) – (TF + TD wheeled)