present work is probably one of those tasks. Adult subjects also showed an association between behavioral activation during the transfer phase and sandpaper scores. These facts suggest that adults are capable of encoding and acquiring information about the state of intoxication and its contingency with the CS, although we cannot discount the possibility that adolescents are more effective or show qualitative differences in this learning. Indeed, when ethanol-mediated conditioned place preference has been found in adult rats, extensive training procedures were employed (Bozarth, 1990; Bienkowsky et al., 1995), whereas one-trial, ethanol-mediated second-order conditioning seems to be a reliable phenomenon earlier in the ontogeny of the rat (Molina et al., 2006; 2007). It could also be postulated that late paired animals might have been trained via a backward rather than simultaneous or delay conditioning (i.e., with the CS following the US). Thus, the appearance of age differences might relate to differences in backward conditioning.
