Table 1.
Schedule of experimental phases
| Phase | Number of Daysa | Stimuli | Stimulus Presentation |
|---|---|---|---|
| Operant Training | |||
| Stationary Training | 3 | Water | Ad libitum |
| Side Training | 4 | 0.4 M NaCl or water | Constant |
| Alternation | 4 | 0.4 M NaCl and water | Semirandom |
| Random Training | 5 | 0.4 M NaCl and water | Semirandom |
| NaClb in Water I | 22 | NaCl vs. water | Semirandom |
| NaClc in 0.3 M sucrose | 18 | NaCl+0.3 M Sucrose vs. 0.3 M Sucrose | Semirandom |
| Masking concentration series | |||
| NaClb Masked by Sucrose | |||
| NaCl in 0.6 M sucrose | 15 | NaCl+0.6 M Sucrose vs. 0.6 M Sucrose | Semirandom |
| NaCl in 1.0 M sucrose | 16 | NaCl+1.0 M Sucrose vs. 1.0 M Sucrose | Semirandom |
| NaCl in Water II | 20 | NaCl vs. Water | Semirandom |
| Sucroseb Masked by NaCl | |||
| Sucrose in Water | 14 | Sucrose vs. Water | Semirandom |
| Sucrose in 0.4 M NaCl | 12 | Sucrose+0.4 M NaCl vs. 0.4 M NaCl | Semirandom |
| Sucrose in 0.2 M NaCl | 12 | Sucrose+0.2 M NaCl vs. 0.2 M NaCl | Semirandom |
| Sucrose in 0.04 M NaCl | 14 | Sucrose+0.04 M NaCl vs. 0.04 M NaCl | Semirandom |
a Days were sequential but not necessarily consecutive.
b When used as the target stimulus, the first NaCl concentration tested was always 0.4 M, and the first sucrose concentration tested was always 0.3 M. One concentration of the target stimulus was used in a single session with the concentration decreased across sessions.
c The target stimulus was dissolved in the listed masker, filled to an appropriate volume. Thus, the discrimination for each phase is as listed as: Target+Masker vs. Masker.