Simultaneous discrimination reversal learning in pigeons and humans: anticipatory and perseverative errors

Abstract

Pigeons were trained on a two-choice simultaneous discrimination (red vs. green) that reversed midway through each session. After considerable training, they consistently made both anticipatory errors prior to the reversal and perseverative errors after the reversal, suggesting that time (or number of trials) into the session served as a cue for reversal. In Experiment 2, to discourage the use of time as a cue, we varied the location of the reversal point within the session such that it occurred semirandomly after Trial 10, 25, 40, 55, or 70. Pigeons still tended both to anticipate and to perseverate. In Experiment 3, we required 20 pecks to a stimulus on each trial to facilitate memory for the preceding response and sensitivity to local reinforcement contingencies, but the results were similar to those of Experiment 2. We then tested humans on a similar task with a constant (Experiment 4) or variable (Experiment 5) reversal location. When the reversal occurred consistently at the midpoint of the session, humans, like pigeons, showed a tendency to anticipate the reversal; however, they did not show perseverative errors. When the reversal location varied between sessions, unlike pigeons, humans adopted a win-stay/lose-shift strategy, making only a single error on the first trial of the reversal.

Midsession shifts in reward probability and the control of behavioral variability

“…2). Recent research has demonstrated that pigeons both anticipate upcoming shifts in the location of reinforced responses and perseverate on nonreinforced responses that were reinforced prior to said shifts (e.g., Cook & Rosen, 2010;Rayburn-Reeves et al 2011). Lacking from the body of research was an examination of whether variability in behavior would show either an anticipatory or a perseverative bias in an analogous task in which the reinforcement probability changed in the middle of a session.…”

“…A common procedure when working with data germane to the topic of the maintenance of behavioral variability is to omit early sessions, in which the animals would not yet have had the opportunity to learn about the relevant aspects of potentially controlling stimuli (e.g., Rayburn-Reeves et al, 2011;Stahlman & Blaisdell 2011a, b). Therefore, we report analyses using the final 20 sessions of collected data.…”

“…Thomas Zentall and his colleagues have investigated a striking example of inefficient choice behavior in nonhuman animals (e.g., Laude, Stagner, Rayburn-Reeves, & Zentall, 2014;Rayburn-Reeves, Molet, & Zentall, 2011;Rayburn-Reeves, Stagner, Kirk, & Zentall, 2013;Stagner, Michler, Rayburn-Reeves, Laude, & Zentall, 2013; see also Cook & Rosen, 2010;Daniel, Cook, & Katz, 2015;McMillan & Roberts, 2015;McMillan, Sturdy, & Spetch, 2015). An early article in this experimental series presents several experiments that are illustrative of the basic effect.…”

“…Therefore, it is important to study not just, for example, choice behavior, but also the degree to which it is similar to (or different from) other emitted responses. For example, Rayburn-Reeves et al, (2011) could have also collected beak aperture, the distance of responses from the center of the color cues, or the interpeck interval. These kinds of measures would reveal whether other aspects of pecking behavior changed as a function of the reinforcement contingencies.…”

“…An early article in this experimental series presents several experiments that are illustrative of the basic effect. Rayburn-Reeves et al (2011) trained pigeons on a task in which two possible response options were indicated by readily discriminable color cues: simultaneously presented red and green discs. For the first half of the training sessions, pigeons were reinforced with grain for only responding to one of the two color cues; beginning with the first trial of the second half, the reinforced response shifted to the other disc.…”