A psychologist investigates whether pupils identify more matching pairs of abstract symbols when the symbols are printed on white paper or pale yellow paper. The psychologist uses the same symbol-matching task, instructions and time limit in both conditions.
The results of the first study are shown below.
| Paper colour | Lighting level | Mean number of matching pairs identified out of 24 |
|---|---|---|
| White | 500 lux | 19.6 |
| Pale yellow | 150 lux | 14.1 |
The psychologist repeats the study using the same procedure, but both paper-colour conditions are now tested under lighting of 500 lux.
| Paper colour | Lighting level | Mean number of matching pairs identified out of 24 |
|---|---|---|
| White | 500 lux | 19.4 |
| Pale yellow | 500 lux | 18.9 |
Explain whether the first study provides valid evidence that paper colour affected performance. Use the results from both studies in your answer.
182 exam-style questions on OCR GCSE Psychology 7.1 Planning Research, covering 7.1.1 Hypotheses, 7.1.2 Variables, 7.1.3 Experimental Designs, 7.1.4 Populations and Sampling, 7.1.5 Ethical issues, and 7.1.6 Dealing with ethical issues and BPS Code. Each one has a worked solution and a mark scheme showing where the marks go.