Table 2.

Progressive ratio responding for chow A/I pellets

Parameter	Latency, ln s [s]		Reinforcers		Session Duration, ln min [min]
Group	Chow A/I / Chow A/I	Chow A/I / Preferred	Chow A/I / Chow A/I	Chow A/I / Preferred	Chow A/I / Chow A/I	Chow A/I / Preferred
Baseline (Week 1)	4.97±0.22 [144–28.4]	4.99±0.40 [146.9–48.4]	13.2±0.7	12.5±0.9	3.21±0.06 [24.8–1.4]	3.1±0.06 [22.2–1.3]
Week 2	4.47±0.18 [87.4–14.4]	4.90±0.39 [134.3–43.4]	14.0±0.7	10.6±1.3*#	3.38±0.06 [29.4–1.7]	3.07±0.08 [21.5–1.7]**
Week 3	4.43±0.20 [83.9–15.2]	5.03±0.42 [152.9–52.4]	14.0±1.1	9.8±1.2**###	3.31±0.09 [27.4–2.4]	3.01±0.06 [20.3–1.2]**#
Week 4	4.46±0.22 [86.5–17.1]	4.99±0.48 [146.9–56]	12.6±0.9	8.8±1.3*###	3.23±0.07 [25.3–1.7]	3.05±0.07 [21.1–1.4]*
Week 5	4.27±0.26 [71.5–16.4]	4.96±0.48 [142.6–54.4]	12.7±0.7	9.1±1.1**###	3.19±0.08 [24.3–1.9]	2.97±0.05 [19.5–1.0]*##

Effects of repeated cycles of 5-day access to Chow A/I alternated by 2-day access to either Chow A/I (Chow A/I / Chow A/I, n = 14) or highly preferred chocolate-flavored sugary diet (Chow A/I / Preferred, n = 15) on progressive ratio responding for Chow A/I pellets in male Wistar rats. Values show the means ± SE of the 5-day averages from each week. Bracketed values show the backtransformed means ± SE to facilitate interpretation.

^*Significant difference from Chow A/I / Chow A/I P < 0.05,

^**P < 0.01.

^#Significant difference from respective baseline (week 1) P < 0.05,

^##P < 0.01,

^###P < 0.001.