Table 1.

Appetitive measures during FR and RR reinforcement schedules. Values are the mean ± SEM of the last 3 sessions on each reinforcement schedule. Data for the first completed response requirement in mice on the FR4 schedule is depicted (except when noted), for comparison with RR schedule parameters. Response latency reflects time from session start whereas latency to 1^st lick denotes time from the onset of sipper access.

	Reinforcement Schedule
	FR4	RR4	RR8
Active Lever
Total Session Responses	33.6 ± 2.4	---	---
Response Latency (sec)	135 ± 24	89 ± 15*	79 ± 13**
Response Rate (press/sec)	1.46 ± 0.34	1.14 ± 0.24	0.57 ± 0.18**
Latency to 1st Lick (sec)†	153 ± 51	70 ± 14	53 ± 13
Inactive Lever
Total Session Responses	5.9 ± 1.0	---	---
Responses Prior to 1st Sipper Access	0.4 ± 0.1	0.6 ± 0.2	2.3 ± 0.5***,###

^*p < 0.05

^**p < 0.01

^***p < 0.001 versus the FR4 schedule

^###p < 0.001 versus the RR4 schedule

^†p = 0.07 for log₁₀-transformed values (data not shown).