Table 1.

Distribution of sign- and goal-tracking animals by sex and drug exposure (SAL = saline, NIC = nicotine). A tracking score (see text) was calculated for each rat, based on conditioned approach behavior on the last 4 days of training. The score was used to classify rats within sex and drug exposure group as goal-trackers, intermediate, or sign-trackers

	Goal-tracker	Intermediate	Sign-tracker
SAL Female, n = 12	25%	50%	25%
NIC Female, n = 12	0%	58%	42%
SAL Male, n = 13	46%	31%	23%
NIC Male, n = 11	9%	82%	9%