Temporal context effects on suboptimal choice.

Choice can be driven both by rewards and stimuli that signal those rewards. Under certain conditions, pigeons will prefer options that lead to less probable reward when the reward is signaled. A recently quantified model, the Signal for Good News (SiGN) model, assumes that in the context of uncertainty, signals for a reduced delay to reward reinforce choice. The SiGN model provides an excellent fit to previous results from pigeons and the current studies are the first to test a priori quantitative predictions. Pigeons chose between a suboptimal alternative that led to signaled 20% food and an optimal alternative that led to 50% food. The duration of the choice period was manipulated across conditions in two experiments. Pigeons strongly preferred the suboptimal alternative at the shorter durations and strongly preferred the optimal alternative at the longer durations. The results from both experiments fit well with predictions from the SiGN model and show that altering the duration of the choice period has a dramatic effect in that it changes which of the two options pigeons prefer. More generally, these results suggest that the relative value of options is not fixed, but instead depends on the temporal context.

Suboptimal choice: A review and quantification of the signal for good news (SiGN) model.

As first reported several decades ago, pigeons (Columba livia) sometimes choose options that provide less food over options that provide more food. This behavior has been variously referred to as suboptimal, maladaptive, or paradoxical because it lowers overall food intake. A great deal of research has been directed at understanding the conditions under which animals and people make suboptimal choices and the mechanisms that drive this behavior. Here, we review the literature on suboptimal choice and the variables that play a role in this phenomenon. Suboptimal choice is most likely to occur when the outcomes following a choice are uncertain, when the outcomes are delayed after the choice, and when the outcomes are signaled only on the option that provides food less often. We propose a mathematical formalization of the signal for good news (SiGN) model which assumes that a signal for a reduction in delay to food reinforces choice. We generate predictions from the model about the effect of parameters that characterize suboptimal choice and we show that, even in the absence of free parameters, the SiGN model provides a very good fit to the choice proportions of birds from a large set of conditions across studies from numerous researchers. R code for SiGN predictions and the data set are available on the Open Science Framework (https://osf.io/39qtj). We discuss limitations of the model, propose directions for future research, and discuss the general applicability of this research to understanding how rewards and signals for reward may combine to reinforce behavior. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Forced-exposure trials increase suboptimal choice.

The influence of single option or forced-exposure (FE) trials was studied in the suboptimal choice task. Pigeons chose between an optimal alternative that led to food half of the time and a suboptimal alternative that led to food 20% of the time. Choice of the suboptimal alternative was compared across groups of subjects that received different numbers of FE trials during training. In Experiment 1, subjects received 100% FE trials, 67% FE trials, or only choice trials. Pigeons in the two groups that had FE trials developed extreme preference for the signaled suboptimal alternative over the unsignaled optimal alternative, while pigeons that had no FE trials showed pronounced individual differences. Experiment 2 compared 10% and 90% FE trials. When neither alternative signaled trial outcomes, both groups of subjects strongly preferred the optimal alternative. When the suboptimal alternative provided differential signals, the subjects in the 90% FE group developed strong preference for the suboptimal alternative and subjects in the 10% FE group maintained preference for the optimal alternative. The results of both experiments demonstrate that FE trials can have substantial effects on the development of preference in the suboptimal choice task.

Good news is better than bad news, but bad news is not worse than no news.

Under certain conditions, pigeons will reliably prefer an alternative that leads to a lower probability of food over an alternative that leads to a higher probability of food (i.e., demonstrate suboptimal choice). A critical aspect of the typical procedure is that the alternative associated with less food provides differential stimuli that signal trial outcomes, but the alternative associated with more food does not. Few studies have investigated how partial signaling of an alternative influences preference. In Experiments 1-3, pigeons chose between two alternatives that each led to food 60% of the time with partially signaled trial outcomes. One alternative occasionally provided a stimulus that always preceded food (i.e., "good news") and the other alternative occasionally provided a stimulus that always preceded no food ("bad news"). Experiments 2 and 3 also assessed preference in conditions in which alternatives were either completely unsignaled (provided no differential stimuli) or always led to food. Pigeons consistently preferred the "good news" alternative over the "bad news" alternative and preferred 100% food over the "bad news" alternative. The results from conditions in which pigeons chose between the "bad news" alternative and an unsignaled alternative were inconclusive, but suggestive of a preference for bad news. The results are used to evaluate and distinguish between competing explanations of suboptimal choice.

The Near-Miss Effect in Slot Machines: A Review and Experimental Analysis Over Half a Century Later.

In games of chance, a near miss is said to occur when feedback for a loss approximates a win. For instance, obtaining "cherry-cherry-lemon" on a slot machine could be considered a near miss. Sixty-six years ago, B.F. Skinner first proposed the idea that near-miss events might reinforce continued play in slot machines, and despite some inconsistencies in the experimental literature, belief in this "near-miss effect" has remained strong. In the present manuscript, we will review this literature and present experimental assessments of the near-miss effect on the frequency of the gambling response. Experiment 1 used a tightly controlled resistance-to-extinction procedure in pigeons to evaluate the putative reinforcing effect of near misses relative to a control "far-miss" reel pattern. Experiment 2 extended Experiment 1's procedure to human participants. The results of both experiments failed to support the near-miss effect hypothesis. Experiment 3 used a further simplified procedure to assess the validity of the resistance-to-extinction paradigm when a probable conditional reinforcer was present on the reel stimuli. Although a clear conditional response was obtained from the reel, subsequent testing in extinction revealed no conditionally reinforcing function of this stimulus on operant response frequency.

Suboptimal choice and initial-link requirement.

Pigeons (n = 14) were trained in a concurrent-chains suboptimal choice procedure that tested the effect of an increased ratio requirement in the initial links. Fixed-ratio 1 and 25 conditions were manipulated within subjects in a counterbalanced order. In all conditions, distinct terminal-link stimuli on a suboptimal alternative signaled either primary reinforcement (20% of the time) or extinction (80% of the time). On an optimal alternative, two distinct terminal-link stimuli each signaled a 50% chance of primary reinforcement. Preference for the suboptimal alternative was significantly attenuated, and in some birds completely reversed, by the larger response requirement irrespective of condition order. This larger response requirement also generated a notable increase in between-subject variability. A measure of cumulative choice responding is introduced to mitigate the problems associated with traditional session averages. Ordinal predictions of some current theories of suboptimal choice are also considered in light of the results.

The power of nothing: Risk preference in pigeons, but not people, is driven primarily by avoidance of zero outcomes.

Both human and nonhuman animals regularly need to make choices where the outcomes of their actions are unpredictable or probabilistic in some way. These are often termed "risky" choices. Faced with uncertain rewards, people (Homo sapiens) and pigeons (Columba livia) often show similar choice patterns. When the reward probabilities of risky choices are learned through experience, preferences in both species seem to be disproportionately influenced by the extreme (highest and lowest) outcomes in the decision context. Overweighting of these extremes increases preference for risky alternatives that lead to the highest outcome and decreases preference for risky alternatives that lead to the lowest outcome. In a series of studies, we systematically examine how this overweighting of extreme outcomes in risky choice generalizes across 2 evolutionary distant species: pigeons and humans. Both species showed risky choices consistent with an overweighting of extreme outcomes when the low-value risky option could yield an outcome of 0. When all outcome values were increased such that none of the options could lead to 0, people but not pigeons still overweighted the extremes. Unlike people, pigeons no longer avoided a low-value risky option when it yielded a nonzero food outcome. These results suggest that, despite some similarities, different mechanisms underlie risky choice in pigeons and people. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Frequency and value both matter in the suboptimal choice procedure.

Pigeons chose between two options on a concurrent-chains task with a single response requirement in the initial link. The suboptimal option ended with food 20% of the time whereas the optimal option ended with food 80% of the time. During a Sig-Both condition, terminal-link stimuli on both options signaled whether or not food would occur. During a Sig-Sub condition, terminal-link stimuli on the suboptimal option provided differential signals, but stimuli on the optimal option did not differentially signal the food and no food outcomes. Initial-link choices revealed a clear preference for the optimal option in the Sig-Both condition, but preference shifted toward suboptimality in the Sig-Sub condition. These findings show that pigeon suboptimal choice is not singularly driven by signal value, as has been suggested, but also by reinforcer frequency.

The influence of outcome delay on suboptimal choice.

Under certain conditions pigeons will choose an option that provides less probable food over one that provides more probable food. This suboptimal choice behavior occurs when the outcomes are delayed and stimuli during the delay differentially signal the upcoming outcomes on the suboptimal alternative, but not the optimal alternative. The present study assessed whether duration of the outcome delay affects pigeons' suboptimal preference. Pigeons chose between a suboptimal alternative that provided food 20% of the time and an optimal alternative that provided food 80% of the time. Stimuli presented during the delays signaled the outcomes on the suboptimal alternative, but not on the optimal alternative. The outcome delays were 5 s in some conditions and 20 s in others. The results of two experiments demonstrate that behavior is generally more suboptimal when the outcome delays are longer but tends to stay relatively suboptimal if subjects experience the long delay condition before the short delay condition. The finding that behavior is more suboptimal with longer delays to the outcomes is consistent with the view that pigeons' suboptimal choice is influenced by both conditioned and primary reinforcement and is inconsistent with the view that suboptimal choice is influenced solely by signal value.

Pigeons perform poorly on a midsession reversal task without rigid temporal regularity.

Animals make surprising anticipatory and perseverative errors when faced with a midsession reversal of reinforcer contingencies on a choice task with highly predictable stimulus-time relationships. In the current study, we asked whether pigeons would anticipate changes in reinforcement when the reinforcer contingencies for each stimulus were not fixed in time. We compared the responses of pigeons on a simultaneous choice task when the initially correct stimulus was randomized or alternated across sessions. Pigeons showed more errors overall compared with the typical results of a standard midsession reversal procedure, and they did not show the typical anticipatory errors prior to the contingency reversal. Probe tests that manipulated the spacing between trials also suggested that timing of the session exerted little control of pigeons' behavior. The temporal structure of the experimental session thus appears to be an important determinant for animals' use of time in midsession reversal procedures.

When good pigeons make bad decisions: Choice with probabilistic delays and outcomes.

Pigeons chose between an (optimal) alternative that sometimes provided food after a 10-s delay and other times after a 40-s delay and another (suboptimal) alternative that sometimes provided food after 10 s but other times no food after 40 s. When outcomes were not signaled during the delays, pigeons strongly preferred the optimal alternative. When outcomes were signaled, choices of the suboptimal alternative increased and most pigeons preferred the alternative that provided no food after the long delay despite the cost in terms of obtained food. The pattern of results was similar whether the short delays occurred on 25% or 50% of the trials. Shortening the 40-s delay to food sharply reduced suboptimal choices, but shortening the delay to no food had little effect. The results suggest that a signaled delay to no food does not punish responding in probabilistic choice procedures. The findings are discussed in terms of conditioned reinforcement by signals for good news.

Reward context determines risky choice in pigeons and humans.

Whereas humans are risk averse for monetary gains, other animals can be risk seeking for food rewards, especially when faced with variable delays or under significant deprivation. A key difference between these findings is that humans are often explicitly told about the risky options, whereas non-human animals must learn about them from their own experience. We tested pigeons (Columba livia) and humans in formally identical choice tasks where all outcomes were learned from experience. Both species were more risk seeking for larger rewards than for smaller ones. The data suggest that the largest and smallest rewards experienced are overweighted in risky choice. This observed bias towards extreme outcomes represents a key step towards a consilience of these two disparate literatures, identifying common features that drive risky choice across phyla.

Reorientation in diamond-shaped environments: encoding of features and angles in enclosures versus arrays by adult humans and pigeons (Columbia livia).

Although geometric reorientation has been extensively studied in numerous species, most research has been conducted in enclosed environments and has focused on use of the geometric property of relative wall length. The current studies investigated how angular information is used by adult humans and pigeons to orient and find a goal in enclosures or arrays that did not provide relative wall length information. In enclosed conditions, the angles formed a diamond shape connected by walls, whereas in array conditions, free-standing angles defined the diamond shape. Adult humans and pigeons were trained to locate two geometrically equivalent corners, either the 60° or 120° angles. Blue feature panels were located in the goal corners so that participants could use either the features or the local angular information to orient. Subsequent tests in manipulated environments isolated the individual cues from training or placed them in conflict with one another. In both enclosed and array environments, humans and pigeons were able to orient when either the angles or the features from training were removed. On conflict tests, female, but not male, adult humans weighted features more heavily than angular geometry. For pigeons, angles were weighted more heavily than features for birds that were trained to go to acute corners, but no difference in weighting was seen for birds trained to go to obtuse corners. These conflict test results were not affected by environment type. A subsequent test with pigeons ruled out an interpretation based on exclusive use of a principal axis rather than angle. Overall, the results indicate that, for both adult humans and pigeons, angular amplitude is a salient orientation cue in both enclosures and arrays of free-standing angles.