We found that the high drinking lines showed a greater increase in RT during the session than the low drinking lines. The results of experiment 2 are more difficult to interpret due to long baseline RTs in the progenitor HS/Ibg line. While it is typical to see increases in RT later in a session, larger relative increases in RT are interpreted by some researchers as impaired sustained attention (Pattyn et al., 2008; Shimizu et al., 2008; Whyte et al., 1995). If these data were regarded as deficits in sustained attention, it would be consistent with studies performed in humans that have shown a correlation between drug abuse and impaired attention (Aharonovich et al., 2003; Cairney et al., 2007; Lane et al., 2007; Mackin et al., 2005). Error rates rather than RT are the most common method of evaluating sustained attention, which is impossible to assess in this version of the DD paradigm, as there is no “incorrect” response. Other reasonable explanations for line differences in RT increases would be fatigue, boredom, working memory, or differences in motivation and/or satiation. Without
