Preliminary statistical analysis indicated that adolescent unpaired groups spent similar amounts of time (indexed both in seconds and percent time) on the CS2 at test regardless of the interval between habituation and CS1 exposure (i.e., Early or Late adolescent unpaired groups) [F (1, 34) = 0.15, for 0.5 g/kg unpaired animals; F (1, 34) = 0.36, for 2.0 g/kg unpaired animals; both ps > 0.55]. Further analysis of the data based on behavioral responsiveness during the second-order phase also indicated that these unpaired conditions did not differ [F (1, 34) = 0.01; F (1, 34) = 0.04; F (1, 34) = 0.50; for locomotion, wall-climbing and head shaking, respectively; all ps > 0.45]. Hence, data corresponding to the unpaired adolescent controls were collapsed across timing of CS1 exposure. This manipulation, which does not preclude analysis of pertinent interactions, allowed simplification in analysis and presentation of the data set (see Pautassi et al., 2005; Roth et al., 2006: Thiele et al., 1998).
