Simultaneous and successive shifts in reinforcer magnitude and influence of discrimination task.

Abstract

Rat received 12 or 1 food pellets in alternatives discriminable by brightness, by position, or by combined brightness and position. Asymptotic running speed to the larger reinforcer and change in speeds following a reduction in reinforcer magnitude was greater with the latter two tasks, but the simultaneous contrast effect and choice behavior were relatively unaffected. Relative performance for alternative reinforcers appears to be somewhat dependent upon generalization between discriminanda, as previously suggested by others, regardless of concurrent choice behavior.After rats apparently have discriminated two distinctive runways associated with different reinforcer magnitudes, there is a tendency toward slower running speed for the larger reinforcer the smaller the reinforcer in the alternative runway (e.g., MacKinnon, 1967). However, analogous experiments employing a T-maze positiondiscrimination task have found performance for the larger reinforcer to be uninfluenced by the alternative reinforcer (e.g., Spear & Hill, 1965) or a trend opposite that found with alternative runways (e.g., Spear & Pavlik, 1966; Spear & Spitzner, 1966). Unfortunately, these relationships are not completely generalizable, since at least one experiment employing distinctive runways (Goldstein & Spence, 1963) has failed to find the effect reported by MacKinnon and others, and at least one T-maze experiment has found the effect (Spear & Spitzner, 1969). MacKinnon (1967) has interpreted this discrepancy in terms of differential tendencies for inhibition to generalize from the less favorable alternative (LFA) to the more favorable alternative (MFA). But, some of the position-discrimination mazes not yielding the effect have had equal-

Reward shifts in forced-choice and free-choice autoshaping with rats.

“…SNC effects have been explored in free-choice situations with mixed results. In some maze studies, animals showed reduced running speeds after the downshift in forced choice situations (i.e., when there was a single alternative and the option was to respond or not), but exhibited no tendency to prefer the unshifted option when given a free choice (e.g., Spear & Spitzner, 1969). This result was considered puzzling, given that rats are known to learn to escape from situations associated with surprising reward reductions (e.g., Daly, 1974).…”

Effects of task-irrelevant cues and reinforcement delay on choice-escape learning following inescapable shock: Evidence for a deficit in selective attention.

“…comes from studies of choice responding in rats following exposure to inescapable shock (Jackson, Alexander, & Maier, 1980;Rosellini, DeCola, & Shapiro, 1982). Choice tasks have been used to decide among performance-deficit and learning-deficit hypotheses (Logan, 1968;Spear, 1964;Spear & Spitzer, 1966, 1969. The rationale is that variables influencing performance should affect response speed and not choice accuracy, whereas variables influencing associative processing should affect accuracy.…”

Why Pigeons Say What They Do: Reinforcer Magnitude and Response Requirement Effects on Say Responding in Say—do Correspondence

“…The use of reinforcement magnitudes to alter choice between concurrently available alternatives can be traced to Catania (1963) who exposed pigeons to concurrent variable‐interval (VI) VI reinforcement schedules and manipulated the duration of grain presentations correlated with each key across conditions to produce accompanying changes to responding. This relation between reinforcer magnitude and choice has been replicated repeatedly (e.g., Brownstein, 1971; Neuringer, 1967; Schneider, 1973; Spear & Spitzner, 1969; Todorov, 1973) in the laboratory and in applied settings. For example, Hoch, McComas, Johnson, Faranda, and Guenther (2002) manipulated the amount of time allowed for playing with a toy (reinforcer) to investigate the allocation of playing across two concurrently available play areas: one with a peer (peer area) and one without a peer (no‐peer area).…”