Table 1.

Outline of Experimental Procedures

	Experiment 1
	Pre-exposure	Conditioning	Test
Group Real1:	O1F, O2	FO1O2→toxin	O1, O2
Group Real2:	O1, F, O2	FO1O2→toxin	O1, O2
Group Rep:	O1F, O2	O1O2→toxin	O1, O2
Group Con:	O1, F, O2	O1O2→toxin	O1, O2
	Experiment 2
	Pre-exposure	Conditioning	Test
Group Con:	O1, (F1), O2, (F2)	O1O2→toxin	O1, O2
Group One:	O1F1, O2, (F2)	O1O2→toxin	O1, O2
Group Two:	O1F1, O2F2	O1O2→toxin	O1, O2
	Experiment 3
	Pre-exposure	Conditioning	Test
Group Con:	(O1), F1, (O2), F2	F1F2→toxin	F1, F2
Group One:	O1F1, (O2), F2	F1F2→toxin	F1, F2
Group Two:	O1F1, O2F2	F1F2→toxin	F1, F2
	Experiment 4
	Pre-exposure	Conditioning	Test
Group Con:	O1, F1, O2, F2	O1O2O3→toxin	O3, O2, O1
Group One:	O1F1, O2, F2	O1O2O3→toxin	O3, O2, O1
Group Two:	O1F1, O2F2	O1O2O3→toxin	O3, O2, O1

Notes. F = sucrose flavor, F1 and F2 = sucrose and saline flavors, counterbalanced, O1 and O2 = almond and vanilla odors, counterbalanced; O3 = lemon odor. In Experiments 2 and 3, half of the rats in Groups Con and One also received the trials noted parenthetically. In Experiments 1–3, test order was counterbalanced, whereas in Experiment 4 the test order was that shown in the table.