Table 1.

Slopes of linear regressions of amounts of pollen analogue received by stigmas of artificial flowers, regressed on the position of the column within the array

Statistic	Dye received by all flowers			Dye received by yellow flowers				Dye received by blue flowers
	1. Total dye	2. Dye from blue flowers	3. Dye from yellow flowers	4. Total dye	5. Dye from blue flowers	6. Dye from yellow flowers	7. Yellow purity (fraction of conspecific dye)	8. Total dye	9. Dye from blue flowers	10. Dye from yellow flowers	11. Blue purity (fraction of conspecific dye)
Trials with positive slopes	14/14	14/14	0/14	11/14	11/14	6/14	1/14	10/14	13/14	2/14	14/14
Mean slope	0.075	0.162	−0.100	0.039	0.108	−0.016	−2.410	0.054	0.089	−0.087	2.316
s.d.	0.035	0.047	0.068	0.057	0.095	0.081	2.473	0.077	0.092	0.079	1.699
t	8.085	15.694	−11.222	2.607	6.409	−0.813	−6.055	2.628	3.542	−4.965	4.913
P	<0.0001	<0.0001	<0.0001	0.0115	<0.0001	0.2159	<0.0001	0.0110	0.0020	0.0002	0.0002

Positive values indicate that the variable increases from the less rewarding yellow end of the array to the more rewarding blue end. Within each trial, data for dye receipt by ‘all flowers’ have sample sizes of n = 192 stigma loads. Data for receipt by single colours are based on n = 60 stigma loads per trial. For data for the 14 separate trials see Supplementary Data Table S1. Values of t are for one-sample tests of the hypothesis that the slope = 0 (with 12 d.f., using pooled standard deviations as explained in the text). P values are given for each test considered alone. Those in bold type remain significant after Bonferroni correction for making 11 tests (0.05/11 = 0.00455).