Table 4. Correlation matrix for pessimism index, mean speed and impulsivity.

	Pessimism index	Mean speed
Mean speed	r = 0.11
	n = 27
	P = 0.580
Impulsivity	r = -0.18	r = -0.11
	n = 27	n = 27
	P = 0.374	P = 0.590

Notes. The correlation matrix was produced for the subset of birds for which all three behavioural measures were available (n = 27). Each cell contains: the Pearson product-moment correlation coefficient (r), the number of birds on which the test is based (n) and the P-value for the correlation (P).