Table 1.

Parameters for all experiments

Study	Stimulus duration	Limited hold	Fixed ITI	Variable ITI	Time-out	Anticipatory time-out	Sessions to criteria
1a	60	0	2	2 (0.25–3.75)	0	0	7
	60	0	4	4 (0.5–7.5)	2	0	2
	10	0	4	4 (0.5–7.5)	2	0	2
	5	1	4	4 (0.5–7.5)	2	0	4
	2	4	4	4 (0.5–7.5)	2	0	7
	1	5	4	4 (0.5–7.5)	2	0	28
1b	1	5	4	NA	2	0	NA
2a	1	2	NA	4 (0.5–7.5)	2	2	15
2b	1	2	NA	4 (0.5–7.5)	2	2	NA

Studies 1a and 2a refer to experiments looking at baseline (undrugged) performance at initial and final parameters, whereas studies 1b and 2b refer to the first and second of the experiments with nicotine. For experiment 1a, where ITI values are shown for both fixed and variable ITI mode, these refer to settings for different groups of mice. All times stated are in seconds. For variable ITI the mean, smallest and largest values are shown.

NA Not applicable