Table 2.
Design of Experiment 2
| Group | Phase 1 (Contexts A & B) |
Phase 2 (Contexts A & B) |
Test |
|---|---|---|---|
| Control-ABB | 4 X→US(A) 4 Y→US(B) |
Context (A), Context (B) | X (B) |
| Massed-ABB | 4 X→US(A) 4 Y→US(B) |
20 X massed (B), Context (A) | X (B) |
| Spaced-ABB | 4 X→US(A) 4 Y→US(B) |
20 X spaced (B), Context (A) | X (B) |
| Control-ABA | 4 X→US(A) 4 Y→US(B) |
Context (A), Context (B) | X (A) |
| Massed-ABA | 4 X→US(A) 4 Y→US(B) |
20 X massed (B), Context (A) | X (A) |
| Spaced-ABA | 4 X→US(A) 4 Y→US(B) |
20 X spaced (B), Context (A) | X (A) |
Note—X and Y were clicker and tone CSs, counterbalanced, and US was a footshock. Numbers next to pairings denote the number of trials. Letters inside parentheses denote the context (A or B) in which acquisition, extinction, or test took place. The physical identities (see the text) of Contexts A and B were counterbalanced. Massed groups were subdivided into subgroups that experienced trials early or late in the extinction session, which was 220 min long.