| Sample size | Experiment type | Source | Source title |
|---|---|---|---|
| 7 | experimental | Call 2010 | Do apes know that they could be wrong? |
| 4 | experimental | Suda-King et al. 2013 | Gorillas' use of the escape response in object choice memory tests |
| 4 | experimental | Suda-King et al. 2013 | Gorillas' use of the escape response in object choice memory tests |