Hassett et al.

Aims

1. To test if sex differences in childrens' toy preferences are from biological factors

2. To investigate if male and female rhesus monkeys have similar toy preferences to human infants

Methodology

Experiment; monkeys observed in their home for 25 years

Independent measures

135 rhesus monkeys; Yerkes National Primate Research Center Field Station

Procedure

7 25-minute observations outdoors

Toys placed 10 meters apart while monkeys were indoors

Toy position was counterbalanced

Toys varied in size, color, shape

Cameras were focused on each toy

2 observers watched with a behavioral checklist: extended touch, hold stationary, sit or seated, carry in hand, manipulate part

Results

Male preference for wheeled toys, 9.77 mean, 73%

No significant female preference: 30% preferred plush, 37% preferred wheeled, 30% no preference

Positive correlation between social rank and frequency of interaction

Strengths

• usual setting, food and water available (ethical)

• behavioral checklist (reliable)

• cameras, no demand characteristics (valid)

Weaknesses

• potential observer bias

• low ecological validity/generalisability