Table 2.

LMER model of caffeine effects on press rate (n = 18).

Fixed effects	B (taps/s)	SE	t(17)	p
Drug	0.20	0.03	7.10	<0.001
Probability
Linear	0.007	0.02	0.32	0.75
Quadratic	−0.02	0.02	0.99	0.34
Reward value	0.002	0.01	0.22	0.83
Expected value (Probability×Reward value)
Linear probability×Reward value	0.02	0.02	0.96	0.35
Quadratic probability×Reward value	−0.009	0.02	0.42	0.68
Drug×Probability
Drug×Linear probability	−0.09	0.07	1.37	0.19
Drug×Quadratic probability	−0.005	0.06	0.08	0.94
Drug×Reward value	−0.03	0.03	0.87	0.40
Drug×Expected value
Drug×Linear probability×Reward value	0.10	0.08	1.36	0.19
Drug×Quadratic probability×Reward value	−0.009	0.02	0.42	0.68
Session
Linear	0.30	0.03	11.86	<0.001
Quadratic	0.10	0.02	4.59	<0.001
Trial order	0.004	0.0006	5.63	<0.001