“…In their basic experimental design (based on one used with pigeons by Bonardi, Rey, Richmond, & Hall, 1993; see also Kaiser, Sherburne, Steirn, & Zentall, 1997), human participants received initial training in which four different geometrical figures (A, B, C, and D) were used to signal two different outcomes. Presentations of A and B were both followed by, for example, the presentation of the nonsense syllable wug; presentations of C and D were both followed by the nonsense syllable zif.…”