Hassett et al.

• Title of Research Study: Monkey Toy Preferences
• One assumption of the biological approach:

  Behaviour, cognitions and emotions can be explained in terms of the working of the brain and the effect of genetics, hormones and evolution.
• Another assumption of the biological approach:

  Similarities and differences between people can be understood in terms of biological factors and their interaction with other factors
• The psychology being investigated:

  • Sex differences and the role of nature - The sex of mammals is determined by sex chromosomes which affect their levels of sex hormones.
  • This causes differences in the development of male and female brains, and consequently, their cognitive processes. In a nursery, boys are more likely to be seen playing with cars, and girls with dolls.
  • However, this doesn’t mean that girls don’t like playing with cars; in fact, research found that girls like playing with trucks more than boys like playing with dolls.
• The Aims of the Study:

  1. To test if sex differences in children’s toy preferences result from biological factors - for example, from prenatal hormone exposure rather than through socialisation
  2. To investigate if male and female rhesus monkeys have similar toy preferences to human infants, despite no socialisation experience with human toys
• The Independent and Dependent variable:

  IV - The sex of the monkeys (appearance of the external sex organs)

  DV - whether the monkeys interacted more with the plush toys or wheeled toys
• Methodology: Field experiment involving a controlled observation, and a correlational study using a behavioural checklist.
• Details about the Participants:

  • 135 monkeys at the Yerkes National Primate Research Center Field Station
  • Included both infant (juveline) and adult monkeys.
  • 14 of the monkeys had previously participated in research on prenatal hormones so they were not included in the current study
  • 39 babies (less than 3 months) were not included as it was very hard to tell them apart - making it difficult to know which sex they were
  • Remaining monkeys - 61 females + 21 males
  • 34 interacted with the toys on more than 5 occasions (23 females + 11 males)
• Sampling Technique: Opportunity Sampling - the monkeys that happened to be there
• Research Design: Independent measures - two groups of monkeys were compared: males and females.
• Main Findings of the Study:

  • Males significantly preferred wheeled toys compared to plush
  • Females showed no significant preference for plush compared to wheeled toys
  • Males and females showed no significant difference in the frequency of interactions of wheeled toys compared to plush
• Main Findings of the Study:

  • Males showed a significantly lower frequency of play with plush toys compared to females
  • Males duration of interaction was significantly longer with wheeled toys compared to plush toys
  • Females duration of interaction was not significantly different between wheeled and plush toys
• Main Findings of the Study:

  • For females, rank significantly correlated with frequency of interaction for both types of toys - not seen for males
  • For females, rank significantly correlated with the duration of play with plush toys but not wheeled toys. Correlation not significant for males
  • For both sexes, rank and frequency of interaction were significantly correlated with both types of toys
  • Age did not affect frequency or duration with both types of toys
• Conclusions:

  • Toy preference in monkeys reflects both behavioural and cognitive biases
  • Influenced by hormones which in turn are affected by some social pressures or pressures to form observable sex differences
• Strengths of the Study:

  • Ethics - upheld the guidelines when working with animals (had access to constant water, twice a day got monkey chow, fresh fruits + vegetables every day)
  • Reliability - operationalised behavioural checklist (e.g. ‘seated on the toy or a part of the toy’.)
  • Validity - data was collected on seven separate 25-minute trials - different pairs of plush and wheeled toys (e.g. the wagon + Winnie the Pooh)
  • Quantitative Data - recorded the duration of individual behaviours in seconds - taken using palm pilots to record start + finish points of each interaction - more objective
• Weaknesses of the Study:

  • Reliability - the standardised procedure was abandoned for one of the trials - one monkey ripped one of the plush toys apart - compromising results
  • Observer bias - researchers who watched the video tapes were very familiar + acquainted w/ the monkeys - their knowledge of the monkey’s gender could have biased their observations - increases subjectivity
  • Generalising - lacked adult males in the sample - 11 males were either juvenile, subadult or elderly - high-ranking male didn’t interact with any of the toys  
• Nurture debate:

  Children learn about gender and societal norms through socialisation, leading them to conform to stereotypical gender roles, and seek out sex-typed toys.

  Hassett et al., however, reject the socialisation explanation for toy preferences and believe in the biological explanation.
• Nature debate:

  Boys and girls play with toys which suit their cognitive abilities, and these depend on each child’s sex hormone levels. Hence, toys are selected due to the play activities they promote, not due to societal norms on ‘gender-appropriate’ toys.
• Living Conditions for the Monkeys:

  • Monkeys were born and bred in a specialised centre
  • They were kept in an outdoor space where their family was 
  • Also had an indoor area where the temperature was controlled
  • Food: biscuits and minerals adapted to them (monkey chow), once a day they got fruits and vegetables. 
  • They had access to both the outdoor and indoor areas at all times.
• Magnitude of Preference:

  • Calculated for frequency and duration, males:
  • Total frequency/frequency duration for wheel - (minus) total frequency/total duration for plush
  • Same for females