Procedure of Experiment 1AEach rat was subjected to one session per day throughout the study: the first squad of rats had a daily fluid access starting at 3:00 p.m., while the second squad had the same daily treatment at 3:50 p.m. The rats were also given 15-min tap water access in the home cages 2 h after the daily session.All rats were deprived of water on Day 0. During Days 1–4, they were adapted to drink tap water for 15 min from the bottles in Contexts A and B in the following order: A-B-A-B. Conditioning was performed on Day 5, when all rats had access to 0.15 M LiCl solution for 15 min in Context A. Thereafter, rats remained there for another 15 min before being returned to their home cages. As mentioned earlier, oral ingestion of LiCl causes a salty taste sensation and post-ingestion malaise. In order to help animals recover from the illness and extinguish a conceivable context-illness association (e.g., Loy, Alvarez,Rey, & Lopez, 1993), all rats were allowed to consume tap water for 15 min in Context A on Day 6.Extinction treatment was administered over the next 5 days (Days 7–11) in Context A for Groups AAA and AAiA orin Context B for Groups ABA and ABiA. Rats in the constant extinction groups (Groups AAA and ABA) were always given0.15 M NaCl. For rats in the graded extinction groups (Groups AAiA and ABiA), compound solutions of NaCl and sucrose we reemployed for the first 4 days as follows: 0.05 M NaCl and 0.09 M sucrose on Day 7, 0.08 M NaCl and 0.06 M sucrose on Day8, 0.10 M NaCl and 0.03 M sucrose on Day 9, and 0.13 M NaCl and 0.015 M sucrose on Day 10. Pure 0.15 M NaCl solution was presented on Day 11 to rats of both graded extinction and constant extinction groups.A critical test lasting 15 min was conducted in Context A for all rats on the next day (Day 12). Notably, the 0.15 M NaCl,rather than the LiCl, solution was employed in testing of the present research. This is because the LiCl yields nonassociative acute post-ingestional illness occurring in the 15-min drinking session (cf. Nachman, 1963), making group differences less detectable.