Drinking in the Dark by young and adult mice of seven age groups. Male and female HS/Npt mice were given access to 20% ethanol in the Drinking in the Dark (DID) test. At the time of the initial test, mice were 3 – 9 weeks old (Group). Total ethanol consumption (g/kg) over the 4 hours on the fourth day of the DID test in each week is plotted, collapsed across sex. Each age group from 3 – 9 Weeks was tested for two consecutive weeks (First week bars are light grey; Second week bars are dark grey). Age groups 3 – 6 Weeks were then treated normally until 9 weeks of age, and then were retested for two consecutive weeks (Week 9 bars are hatched diagonally; Week 10 bars are dotted). The group 7 Week mice were tested for four consecutive weeks, while group 8 Week mice were tested for 3 consecutive weeks (see Table 1). *, significantly greater consumption than in the First week of the same age group (p < 0.05). **, significantly greater consumption than in the First or Second weeks of the same age group (p < 0.01).