Table 1.

Design of experiment 1.

Concurrent training	Pavlovian acquisition	Pavlovian extinction	Transfer test
R1-O1 R2-O2	S1-O1 S2-O1 S3-O2 S4-O2	S1-O1 S2-no O1 S3-O2 S4-no O2	S1:R1/R2 S2:R1/R2 S3:R1/R2 S4:R1/R2

R1/R2 = keyboard response; S = conditioned stimuli; O1 = Tobacco points; O2=Chocolate points.