Optional contemporary study: Haun et al. (2014)

Aim and participants (Study 1)

Aim: to compare whether 2-year-old children, chimpanzees and orangutans give up a strategy they have learned for themselves to match peers who use a different, equally rewarding strategy.

Participants: 18 children (9 girls, 9 boys, mean age 28 months), 12 chimpanzees (mean age about 10 years) and 12 orangutans (mean age about 8.5 years).

Apparatus and procedure

A box had three differently coloured sections, each with a hole on top. Dropping a ball into the right hole released a reward (chocolate drops for children, peanuts for apes).

1. Individual learning: each participant learned that only one section gave rewards, until it chose that section on 8 of 10 consecutive trials.

2. Demonstration: three familiar peers of the same species each used the same alternative section (not the one the participant had learned) twice, so there were six demonstrations, each rewarded.

3. Test: the participant got three balls, one at a time, with the peers watching. Now every section was rewarded. Each choice was coded as switching to the peers' section, staying with its own, or other.

Results and conclusions

• On the first test trial, 12 of 18 children (66.7%) switched to the peers' choice; only 2 of 12 chimpanzees (16.7%) and 2 of 12 orangutans (16.7%) switched.
• Children switched significantly more than both ape species, which did not differ from each other; the apes mostly stuck with what they knew.

Conclusion: even 2-year-old humans adjust their behaviour to match peers; chimpanzees and orangutans rarely do. The authors note apes may be more conservative in general.

Study 2 (optional): 72 two-year-olds; children switched more when choosing in public in front of the peers than in private, and the number of demonstrators (one or three) made no difference, suggesting a normative motive (wanting to fit in).

Evaluation

Strengths: the same apparatus and procedure for all three species allows direct comparison; standardised training criterion (8 of 10); coded behaviour is objective.

Weaknesses: small samples (12 apes per species, fewer than the planned 18); apes were tested through mesh, children on the floor, so conditions were not identical; apes' conservatism rather than lack of conformity may explain the results; ethical care is needed with very young children and captive animals.

Worked example

Calculate the percentage of chimpanzees who switched on the first test trial and compare it with the children.

1. Chimpanzees: 2 / 12 x 100 = 16.7%.
2. Children: 12 / 18 x 100 = 66.7%.
3. Children were 4 times as likely to switch.

Answer: 16.7% of chimpanzees against 66.7% of children.

Check yourself

1. On the first test trial, 12 of 18 children switched to the peers' choice. What percentage is that? Give your answer to 1 decimal place.
   Show answer

   66.7 %. 12 / 18 x 100 = 66.7%.

2. Of the 12 orangutans, 2 switched and 2 chose the third section on the first trial. How many stayed with their own section?
   Show answer

   8. 12 - 2 - 2 = 8 stayed.

3. What learning criterion did participants have to reach before the demonstrations?
   • Choosing every section once
   • Watching three demonstrations
   • Choosing the rewarded section on 8 of 10 consecutive trials
   • Dropping 30 balls in any hole
   Show answer

   Choosing the rewarded section on 8 of 10 consecutive trials. This showed each had learned its own strategy.

4. Which conclusion matches the results of Study 1?
   • Orangutans conformed more than children
   • Children conformed to peers far more than chimpanzees or orangutans
   • All three species conformed equally
   • Chimpanzees conformed more than orangutans
   Show answer

   Children conformed to peers far more than chimpanzees or orangutans. Children switched significantly more; the apes did not differ from each other.

5. In Study 2, children switched more when they chose in public in front of the peers. What does this suggest?
   • Informational influence only: children wanted to be right
   • Obedience to an authority figure
   • Children could not see the box in private
   • Normative influence: children wanted to fit in
   Show answer

   Normative influence: children wanted to fit in. More switching when watched suggests a social, normative motive.

6. Give one weakness of Haun et al. (2014) Study 1.
   Show answer

   The ape samples were small (12 per species), so the results may not generalise to all chimpanzees and orangutans.. Small samples and unequal testing conditions limit conclusions.

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Sources

• Pearson Edexcel International Advanced Subsidiary/Advanced Level in Psychology specification (issue January 2026)
• Pearson International A Level Psychology component guide: WPS01
• Haun, Rekers and Tomasello (2014) Psychological Science 25(12) (full text)
• IAL Psychology revision site: Haun et al. (2014)

Last updated 8 November 2026. Spotted a mistake? Tell us.