In the study by Andrade (doodling), one possible uncontrolled variable was whether the participants had friends with the same names as the people in the mock telephone call.

Mark scheme

Marking points from the official mark scheme (May/June 2021). The mark or mark type is shown in brackets.

1. [2] 1 mark for problem
2. 1 mark for a detail
3. One point must be linked for full 2 marks
4. Lowers validity; (generic problem)
5. as people with friends of the same name will recall better; (linked detail)
6. means Andrade could not be certain that differences were caused by the IV; (generic problem)
7. so it is not the effect of the doodling; (linked detail)
8. [2] 1 mark for solution
9. 1 mark for a detail
10. One point must be linked for full 2 marks
11. Ask people to name their friends; (linked solution)
12. (at least a week) prior to the study/ask friends of the participants to name all their friends; (generic detail)
13. Eliminate people with friends of the same name; (linked solution)
14. by interviewing them after the study; (generic detail)
15. Use really unusual/made up names in the mock telephone call; (linked solution)
16. so that it is unlikely that anyone will have friends with those names; (linked detail)
17. use another feature than names; (linked solution)
18. e.g. use food names (of party foods); (linked solution)