Table 1.

Outline of behavioral training and drug treatment procedures

Behavioral condition	Expectancy phase	Surprise phase	Test phase
Consistent	Light→tone→food Light→tone→nothing	Light→tone→food Light→tone→nothing	Light→food
Shift	Light→tone→food Light→tone→nothing	Light→tone→food Light→ nothing	Light→food
Drug Treatments	None	Experiment 1 NBQX or vehicle prior to sessions Experiment 3 Anisomycin immediately after sessions and vehicle 24 h later (Immediate) or vehicle immediately after sessions and anisomycin 24 h later (Delayed)	Experiment 2 NBQX or vehicle prior to sessions

After a strong light–tone expectancy was established, animals in the shift group were surprised by the omission of the tone (“nothing”) on the nonreinforced trials of the surprise phase. This surprise increased the associability of the light for those animals relative to the consistent group, as demonstrated by enhanced learning of the light–food relation in the test phase.