Fig. 4

Access time compression increased front-loading of alcohol intake of males to the level of females. A Rats were placed in operant boxes at 2 h in the dark cycle (“early sessions”) and returned to the home cage after the 15-min session with an FR3 schedule of reinforcement. After 8 h, rats were placed back in the operant boxes at 10 h in the dark cycle (“late sessions”) and returned to the home cage after the 15-min session. B Average of total alcohol intake of early and C late sessions (n = 8 / sex); D early sessions and E late sessions of total alcohol intake per minute in the session of males; F early sessions and G late sessions of total alcohol intake per minute in the session of females. FR fixed ratio, h hour, min minutes. B + , higher intake in the compressed happy hour access (15-min) sessions compared to the normal (30-min) sessions in both males and females, adjusted p < 0.05; indicated by a main effect of access compression. D–G) + , higher intake in the compressed happy hour access (15-min) sessions compared to the normal (30-min) sessions in males (D and E) and females (F and G), adjusted ps < 0.05; indicated by Bonferroni’s multiple comparisons test post hoc analysis following time × access compression interaction. D–G) White circles, higher intake compared to the average rate of intake of the session in males and females, adjusted ps < 0.05; indicated by Bonferroni’s multiple comparisons test post hoc analysis following time × alcohol intake interaction. Error bars and shading are shown in SEM. A is created with BioRender.com