Study

• Psychology Investigated

  -sex differences: physical differences betw males/females (hormones)

  -dif determined extent behaviors product of biological OR social differences (way society treats m/f)

  
  

  -cultural bias (gender stereotype): toys seen as masculine or feminine such as boys being aggressive and girls being nurturing
• Background

  -humans tend to be difficult to study due to complexity of structure and functions w/ behaviors (environment)/socialization

  -prenatal hormonal exposure affects toy preference

  -models (monkeys) can be used instead to compare having similar genetics/behaviors
• Aim

  -to investigate whether toy preferences in monkeys resemble children to test whether sex dif in toy choice is biologically determined by sex
• Research Method

  -field experiment: normal environment, indoor/outdoor housing area

  (monkeys also not unfamiliar with objects being placed in their encolusre)
• Experimental Design

  -independent measures (comparison)+observations to measure

  -IV: gender of monkeys (male/female)

  -DV: activities with toys

  
  

  -looked for differences + correlations w/ monkeys ranks within social hierarchy

  
  

  -frequency/duration of activities with each toy type

  -data compared to childrens obtained from different study
• Sample

  -21 male and 61 females (out of 135) rhesus monkeys living in natal groups out of Nepal (US?) Yerkes primate research station

  -14 adults not studied: had received hormonal treatment

  -39 young infants: not reliably identified
• Controls

  -access to temperature controlled indoor outdoor env (25x25)

  -water available

  -fed twice a day along with fruits and vegetables
• Procedure

  toys divided into boys/girls toys

  
  

  wheeled: 6 vehicle for boys; length 6-46cm

  -wagon, truck, car, shopping cart

  
  

  plush: 7 soft for girls; length 14-73cm

  -winnie the pooh, raggedy ann, scooby doo, turtle, koala hand puppet
• Procedure

  7 trials, each lasting 25 minutes; observed using 2 video cameras

  1 wheel/plush toy placed 10cm apart in outdoor enclosure while monkeys kept indoors with one towards each toy
• Procedure

  -toys counterbalanced between left/right locations

  analyzed by 2 observations w/ beh checklist: freq of each beh, record of continued activities

  
  

  converted to average freq/duration for individuals

  -not all individuals interacted w/ toys leading to final number of 11 males, 23 females
• Results (Freq)

  comparisons on the number of interactions (frequency) and how long spent w/ toy type (duration)

  
  

  Frequency: (stat)

  -males preferred wheeled toys

  -females showed no preference for either

  
  

  Comparison:

  -females interacted with plush toys more than males

  -no sexual differences for wheeled toys
• Results (Dur)

  Duration:

  -males interacted longer time in total for wheeled/plush

  -females duration did not differ, same length

  no significant difference found between sex comparison

  (no overall dif betw time m/f spend playing w/ wheel/plush)

  'magnitude of preference': total frequencies

  male: wheeled - plush

  female: plush - wheel

  stat: male monkeys had higher preference for masculine toys than females had for plush toys
• Results (Social ranks)

  relationship betw social hierarchy ranks freq/dur similar

  -m/f combined frequency interaction positively correlated for w/p toy

  -males: freq correlated w/ rank

  -females: pos correlated w/ freq interaction both (only for duration p)

  SHOWS: rank related to interaction in females UNLIKELY that social rank is responsible for sex differences in toy preference
• Results (Children)

  data of children taken from another study (Barenbaum and Hines)

  -data correlated with similar patterns
• Conclusions

  -males have stronger preference for masc toys

  -females have more variable/variety in toy preference

  -supports biological explanation for toy preference

  -develop in absence of socialization, as it is present in children (hormonal only response)
• Strengths

  use of animals to eliminate effects of socialization

  -excludes confunding variables (age, social rank)

  standardized: clearly operationalized definition of behavior (beh checklist) to improve validity

  -standard length of 25 mins (one finished 7 mins early due to toy ripping)
• Weaknesses


  differences in way monkey/children compare

  -monkeys: masc/fem toys

  -children: gender stereotypical toys

  only measured duration not frequency* (only sig comp monkey freq w/ child duration not dur for both)

  -children individually, monkeys in groups
• Ethical Issues

  -proper feeding: water, twice a day with fruits and vegetables

  -ethically housed in family group/indoor/outdoor 25x25 enclosure

  -observed using cameras, not distracting

  -one toy destroyed could have been playful act or reflection of distress