An occupational psychologist conducted an experiment to investigate the effect of office lighting on typing accuracy. One group of participants completed a standardized 10-minute copy-typing task under bright fluorescent lighting (500 lux500\text{ lux}500 lux), while another group completed the same task under dim, warm lighting (150 lux150\text{ lux}150 lux).
| Bright Fluorescent Light (500 lux500\text{ lux}500 lux) | Dim Warm Light (150 lux150\text{ lux}150 lux) | ||
|---|---|---|---|
| Participant | Errors | Participant | Errors |
| Participant 1 | 3 | Participant 7 | 8 |
| Participant 2 | 5 | Participant 8 | 11 |
| Participant 3 | 2 | Participant 9 | 7 |
| Participant 4 | 4 | Participant 10 | 9 |
| Participant 5 | 1 | Participant 11 | 12 |
| Participant 6 | 3 | Participant 12 | 10 |
Which of the following would act as an extraneous variable in this study?
The number of typing errors made
The lighting level (150 lux150\text{ lux}150 lux vs. 500 lux500\text{ lux}500 lux)
Prior touch-typing training of the participants
Participant height
