hasset et al. (monkey toy preferences)

biological approach

What are the two aims?

1. To test if sex differences in children’s toy preferences result from biological factors

2. To investigate if female and male rhesus monkeys have similar toy preferences to human infants, despite no socialization experience with human toys.

Which assumption does the study follow?

it follows the assumption that emotions, behaviors, and cognitions, can be controlled by biological systems and processes such as evolution, genes, nervous systems, and hormones.

• link: looking to see if their sex and hormonal differences change their toy preferences

Outline the features of the sample?

sampling technique: opportunity sampling since they got monkeys available to them from the Yerkes National Primate Research Center

final numbers: 34 total (23F 11M)

• began at 89 but then 39 infants were excluded because they couldn’t tell the gender and then another 14 were removed because they were hormonally tested

extra info:

• lived together for 25+ years and were housed with their natal group

• big age range

• follow the mothers

What was the research method?

a natural field experiment with structured and controlled observations because they were tested in their natural environment which is in a lab and the observers had a set list of behaviors they were looking for.

What was the experimental design?

independent measures design

What was the procedure?

prep

• operationalization of variables

• performed 7 trials each lasting 25 min

• prior to each trial the monkey was held in doors

1. prior to each trial, subjects and other social group members were kept indoors while one wheeled and one plush toy were placed outside, 10 meters apart

2. the toy placement (whether it was on the left or right) was counterbalanced across the trials

3. then the monkeys were released into the outdoor area

4. the monkey and toy interactions were videotaped

5. after each trial the toys were removed from the outdoor area

6. the behaviors were coded by 2 observers working together to achieve consensus through a behavioral checklist

7. the exact time at which each activity occurred was also recorded

8. individual monkeys social ranks and age were included as variables in the analysis

What is the independent variable and how was it operationalized?

biological sex: male and female

What was the dependent variable and how was it operationalized?

toy preference: frequency of interaction and duration of interaction

What were some controls used in the study?

• the position of the wheeled and plush toys was counterbalanced across trials

• toys were separated exactly 10 meters apart

• exactly 25 min trials

• each toy was recorded with their own camera

• 2 observers worked together

• behavioral checklist

What are the results for frequency of interactions?

• male monkeys preferred wheel toys. (mean=9.77) compared to plush toys (mean=2.06)

• female monkeys showed no preference, other than the insignificant preference for plush toys (mean=9.97) over wheeled toys (mean=6.96)

What are the results for duration of interactions?

• female monkeys played with plush toys for a longer time than male monkeys

• there wasn’t a significant difference in time spent playing with wheeled or plush toys for females

What are the results based on social rank?

• there was a significant positive correlation between social rank and frequency of interaction

• higher ranking monkeys interacted more with the toys than lower ranked monkeys

• female monkeys who preferred plush toys had a higher rank than females who had no preference

What are the main conclusions?

• sex-typed preferences in humans may be due to biological differences because even without differences in socialization monkeys showed preferences similar to human children.

• male monkeys similar to boys, have a strong preference for masculine-type toys. whereas, female monkeys are more variable in their toy preferences like girls.

• toy preferences reflect behavioral and cognitive biases which have been influenced by hormonesW

Was the generalizability high or low?

low

why:

• small sample size- only 34 monkeys tested

• gender imbalance- 23F 11M

• only monkeys held in captivity were used

• only one species used- rhesus monkeys

High or low reliability?

high

why: procedure was standardized

• each trial was 25 mins

• toys set 10m apart

• 7 trails

• use of behavioral checklist

• 2 observers

What was the psychology being investigated?

hormones and toy preferences: plush or wheeled toys are dependent not on socialization but by the biology of a person

How can the findings be applied to the real world?

• make gender inclusive toys

• help toy companies

• break gender stereotypes

• help toy designers

High or low internal validity?

high

why: used many controls such as

• counterbalanced the side the toys were on

• toys being set 10m apart

• 25 min trials

• camera recording behavior for each toy

High or low external validity?

high

why: tested in their natural environment

• lab was made into an enclosure replicating their natural environment

• tested with their natal group

How were the ethics?

good

• kept in natal group

• housing- born there and kept in their normal environment

• not put in any physical or psychological pain

• had sufficient water and food

• well taken care of

• chose species similar to humans

• used the least amount of animals possible