In the study by Pepperberg (parrot learning), several features of the procedure helped to improve reliability.

Mark scheme

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

1. [1] 1 mark for definition
2. The consistency of a procedure/task/measure;
3. whether the procedure/task/measure produces the same results with the same people each time (it is used);
4. • reliability is about consistency = 1 mark
5. to be reliable, measures must measure the phenomenon in the same way each time = 1 mark
6. [2] 1 mark for feature that helped reliability
7. 1 mark for link
8. standardised (questions)/question all equally hard; (feature)
9. the questions asked were always phrased 'what's same?' or 'what's different?'; (link)
10. There was no risk of improvement within a test; (feature)
11. because the same materials were never presented again during a test; (link)
12. only (very) specific responses were accepted as correct; (feature)
13. e.g. 'colour'/'shape'/'mah mah' for 'matter'; (link)
14. Alex could not guess; (feature)
15. because his 'first trial' performance was measured; (link)