Table 1: Factors influencing performance in the long delay task (Study 1).

Predictors from the full (best-fit) generalized linear mixed model examining trial-by-trial binary responses (correct or incorrect) in Study 1. All models included trial number, species, age cohort, and subject (as a random factor); session (learning versus test) and the species X cohort X session interaction were then added to successive models to test their importance as predictors. Reference values for predictors are indicated in the table.

Factor	Estimate	S.E.	Z	P
Trial number (1–12)	0.154	0.020	7.653	< 0.0001
Species (Bonobo reference)	0.078	0.645	0.120	> 0.90
Cohort (Infant reference)	0.384	0.609	0.631	> 0.52
Session (Learning reference)	1.823	0.431	4.235	< 0.0001
Species X Cohort	−0.201	0.770	−0.261	> 0.79
Species X Session	−0.700	0.525	−1.332	> 0.18
Cohort X Session	−1.509	0.490	−3.082	< 0.005
Species X Cohort X Session	1.619	0.612	2.647	< 0.01