Appendix 3. Benefits and drawbacks of the principal personality assessment methods utilised in studies of non-human primates, synthesised across all studies.

Method	Benefits	Drawbacks
Behavioural Coding	- Produces data which is comparable between subjects - Measurements are objective - Does not require experience with individual animals	- Time-consuming; can take hours to assess each individual - May not account for variability due to confounding variables - Based on observable behaviours in one context
Context Tests	- High level of control limits the impact of confounders - Easy to conduct; the test can be standardised across institutions	- Only measures a small selection of traits (e.g. fearfulness, reactivity) - Not always clear how responses should be measured and interpreted - Based on a few specific behaviours
Trait Rating	- Quick, straightforward to complete - Accounts for variability in behaviour across contexts	- Differences in familiarity with subjects - Measurements depend on subjective judgement - Requires validation to confirm surveyed traits correlate with observable behaviours