Table 1.

Model comparison for Conditions 1 (Delay Vary) and 2 (Immediate Vary).

Models predicting pupil diameter at choice for Condition 1 (Delay Vary) and Condition 2 (Immediate Vary)
Regressors (dependent variable = pupil)	Coefficient (β)	P-value	95% CI	AIC
Condition 1 (delayed rewards varied)
δVchosen	.0001659	0.225	[−.000108, .000439]	−7386.298
δVhighervalue	.0001806	0.177	[−.000086, .0004479]	−7386.727
Vimm δVdel	.0002054 .0000596	0.399 0.768	[−.0002858, .0006966] [−.0003499, .000469]	−7384.171
δVdel - E[δVdel] Vimm - E[Vimm]	.0003716** −.0000398	0.001 0.782	[.0001586, .0005846] [−.0003316 .000252]	−7396.42
Condition 2 (immediate rewards varied)
δVchosen	.0000598	0.713	[−.0001079, .0004397]	−7311.105
δVhighervalue	.0000623	0.700	[−.0000866, .0004479]	−7311.142
Vimm δVdel	.0001709 −.0000843	0.454 0.843	[−.0002858, .0006966] [−.0003499, .000469]	−7312.453
δVdel - E[δVdel] Vimm - E[Vimm]	−.0002744* .0002643**	0.030 0.008	[−.0005206 −.0000282] [.0000747 .0004539]	−7315.808

Dependent variable is relative pupil diameter during choice. In Condition 1 (Delay Vary), pupil dilation is significantly positively predicted by the discounted value of the delayed reward relative to the expected discounted value of the delayed reward (i.e., the discounted value of the delayed reward averaged over the previous 20 trials). In Condition 2 (Immediate Vary), pupil dilation is significantly positively predicted by the value of the immediate reward relative to the expected value of the immediate reward (i.e., the value of the immediate reward averaged over the previous 20 trials). V_imm = value of the immediate reward in dollars; δV_del = discounted value of delayed reward, δV_chosen = value of whichever option (immediate or delayed) was chosen on that trial; δV_highervalue = value of whichever option had the higher value on that trial; E[V_imm] = average of immediate reward values over the previous 20 trials; E[δV_del] = average of discounted delayed reward values over the previous 20 trials.

^*p < 0.05.

^**p<0.01.