The fragile nature of contextual preference reversals: Reply to Tsetsos, Chater, and Usher (2015)

The effect of preference learning on context effects in multi-alternative, multi-attribute choice

Within the domain of preferential choice, it has long been thought that context effects, such as the attraction and compromise effects, arise due to the constructive nature of preferences and thus should not emerge when preferences are stable. We examined this hypothesis with a series of experiments where participants had the opportunity to experience selected alternatives and develop more enduring preferences. In our tasks, the options are presented in a description-based format so that participants need only learn their preferences for various options rather than the objective values of those options. Our results suggest that context effects can still emerge when stable preferences form through experience. This suggests that multi-alternative, multi-attribute decisions are likely influenced by relative evaluations, even when participants have the opportunity to experience options and learn their preferences. We hypothesize what was learned from experience in our tasks is the weights for various attributes. Through model simulations, we show that the observed choice patterns are well captured by a model with unequal attribute weights. A secondary finding is that the direction of observed context effects is opposite to standard effects and appears to be quite robust. Model simulations show that reserved effects can arise through various processes including representational noise and sensitivity to advantages and disadvantages when comparing options.

A robust Bayesian test for identifying context effects in multiattribute decision-making

Research on multiattribute decision-making has repeatedly shown that people's preferences for options depend on the set of other options they are presented with, that is, the choice context. As a result, recent years have seen the development of a number of psychological theories explaining context effects. However, much less attention has been given to the statistical analyses of context effects. Traditionally, context effects are measured as a change in preference for a target option across two different choice sets (the so-called relative choice share of the target, or RST). We first show that the frequently used definition of the RST measure has some weaknesses and should be replaced by a more appropriate definition that we provide. We then show through a large-scale simulation that the RST measure as previously defined can lead to biased inferences. As an alternative, we suggest a Bayesian approach to estimating an accurate RST measure that is robust to various circumstances. We applied the two approaches to the data of five published studies (total participants, N = 738), some of which used the biased approach. Additionally, we introduce the absolute choice share of the target (or AST) as the appropriate measure for the attraction effect. Our approach is an example of evaluating and proposing proper statistical tests for axiomatic principles of decision-making. After applying the AST and the robust RST to published studies, we found qualitatively different results in at least one-fourth of the cases. These results highlight the importance of utilizing robust statistical tests as a foundation for the development of new psychological theories.

Gaze-dependent evidence accumulation predicts multi-alternative risky choice behaviour

Choices are influenced by gaze allocation during deliberation, so that fixating an alternative longer leads to increased probability of choosing it. Gaze-dependent evidence accumulation provides a parsimonious account of choices, response times and gaze-behaviour in many simple decision scenarios. Here, we test whether this framework can also predict more complex context-dependent patterns of choice in a three-alternative risky choice task, where choices and eye movements were subject to attraction and compromise effects. Choices were best described by a gaze-dependent evidence accumulation model, where subjective values of alternatives are discounted while not fixated. Finally, we performed a systematic search over a large model space, allowing us to evaluate the relative contribution of different forms of gaze-dependence and additional mechanisms previously not considered by gaze-dependent accumulation models. Gaze-dependence remained the most important mechanism, but participants with strong attraction effects employed an additional similarity-dependent inhibition mechanism found in other models of multi-alternative multi-attribute choice.

Faced with different choice alternatives, such as food options or risky prospects, our decisions and allocation of gaze (that is where we look) are closely linked, such that items that are looked at longer are often more likely to be chosen. In simple decisions (e.g., choosing between two chocolate bars), these decisions and their associations with gaze allocation are well described by computational models that assume accumulation of evidence in favour of each alternative over time and discounting of momentarily unattended information. However, an important question is whether this class of models can also describe choice behaviour in more complex settings. Specifically, so-called context effects, where preferences between two alternatives can vary with the addition of a third alternative, challenge many models of simple decision making. Our study addresses this question by evaluating gaze-dependent evidence accumulation models in a setting where choices between two risky lotteries are systematically influenced by a third alternative. We find gaze-dependent models to be able to describe context effects because decision-makers‘ gaze allocation also varies with different sets of alternatives.

The repulsion effect in preferential choice and its relation to perceptual choice

People rely on the choice context to guide their decisions, violating fundamental principles of rational choice theory and exhibiting phenomena called context effects. Recent research has uncovered that dominance relationships can both increase or decrease the choice share of the dominating option, marking the two ends of an attraction-repulsion continuum. However, empirical links between the two opposing effects are scarce and theoretical accounts are missing altogether. The present study (N = 55) used eye tracking alongside a within-subject design that contrasts a perceptual task and a preferential-choice analog in order to bridge this gap and uncover the underlying information-search processes. Although individuals differed in their perceptual and preferential choices, they generally engaged in alternative-wise comparisons and a repulsion effect was present in both conditions that became weaker the more predominant the attribute-wise comparisons were. Altogether, our study corroborates the notion that repulsion effects are a robust and general phenomenon that theoretical accounts need to take seriously.

The elusiveness of context effects in decision making

Contextual features influence human and non-human decision making, giving rise to preference reversals. Decades of research have documented the species and situations in which these effects are observed. More recently, however, researchers have focused on boundary conditions, that is, settings in which established effects disappear or reverse. This work is scattered across academic disciplines and some results appear to contradict each other. We synthesize recent findings and resolve apparent contradictions by considering them in terms of three core categories of decision context: spatial arrangement, attribute concreteness, and deliberation time. We suggest that these categories could be understood using theories of choice representation, which specify how context shapes the information over which deliberation processes operate.

A map of decoy influence in human multialternative choice

Imagine you are deciding between two goods: A is simple but inexpensive, B is luxurious but more costly. Introducing a less advantageous option (e.g., lower quality than A, same price) should not alter your choice between A and B. However, this principle is often violated; three classic biases known as “decoy effects” have been identified, each describing a stereotyped choice pattern in the presence of irrelevant information. Through behavioral testing in human participants and computer simulations, we show that these decoy effects are special cases of a wider principle, whereby stimulus value information is encoded in a relative, rather than an absolute, format. This work clarifies the origin of three behavioral phenomena that are widely studied in psychology and economics.

Human decisions can be biased by irrelevant information. For example, choices between two preferred alternatives can be swayed by a third option that is inferior or unavailable. Previous work has identified three classic biases, known as the attraction, similarity, and compromise effects, which arise during choices between economic alternatives defined by two attributes. However, the reliability, interrelationship, and computational origin of these three biases have been controversial. Here, a large cohort of human participants made incentive-compatible choices among assets that varied in price and quality. Instead of focusing on the three classic effects, we sampled decoy stimuli exhaustively across bidimensional multiattribute space and constructed a full map of decoy influence on choices between two otherwise preferred target items. Our analysis reveals that the decoy influence map is highly structured even beyond the three classic biases. We identify a very simple model that can fully reproduce the decoy influence map and capture its variability in individual participants. This model reveals that the three decoy effects are not distinct phenomena but are all special cases of a more general principle, by which attribute values are repulsed away from the context provided by rival options. The model helps us understand why the biases are typically correlated across participants and allows us to validate a prediction about their interrelationship. This work helps to clarify the origin of three of the most widely studied biases in human decision-making.

Framing context effects with reference points

Research on reference points highlights how alternatives outside the choice set can alter the perceived value of available alternatives, arguably framing the choice scenario. The present work utilizes reference points to study the effects of framing in preferential choice, using the similarity and attraction context effects as performance measures. We specifically test the predictions of Multialternative Decision by Sampling (MDbS; Noguchi & Stewart, 2018), a recent preferential choice model that can account for both reference points and context effects. In Experiment 1, consistent with predictions by MDbS, we find a standard similarity effect when no reference point is given that increases when both dimensions are framed negatively and decreases when both dimensions are framed positively. Contrary to predictions by MDbS, when the two dimensions are framed as tradeoffs, participants prefer whichever alternative performs best in the negatively framed dimension. Performance of MDbS was improved by the addition of a frame-based global attention allocation mechanism. Experiment 2 extends these results to a "by-dimension" presentation format in an attempt to bring participant behavior in line with MDbS assumptions. The empirical and modeling results replicated those of Experiment 1. Experiment 3 used the attraction effect to test the effects of framing when the best-performing alternative on each dimension was identical across target conditions, therefore reducing the potential effects of a global attention allocation mechanism. The effects of framing were indeed greatly reduced, and the performance of MDbS was markedly improved. The results extend framing to the context effects literature, provide new benchmarks for models and theories of context effects, and point to the need for a global attention mechanism.

Similarity, Attraction, and Compromise Effects: Original Findings, Recent Empirical Observations, and Computational Cognitive Process Models

Preference reversals—a decision maker prefers A over B in one situation but B over A in another—demonstrate that human behavior violates invariance assumptions of (utility-based) rational choice theories. In the field of multi-alternative multi-attribute decision-making research, 3 preference reversals received special attention: similarity, attraction, and compromise effects. The 3 so-called context effects are changes in (relative) choice probabilities for 2 choice alternatives after a third “decoy” option is added to the set. Despite their simplicity, the effects demonstrate that choice probabilities in multi-alternative decision making are contingent on the local context, that is, on the choice set under consideration. Because of their simplicity, on the other hand, similarity, attraction, and compromise effects have been successfully examined in numerous studies to date, and they have become of increasing interest for differentiating between computational cognitive process models of multi-alternative multi-attribute decision making. However, the stimulus arrangement for producing the effects seems to vary between studies, which becomes challenging when model accounts are compared. The purpose of this review is to present various paradigms in a coherent way and describe various model accounts based on a common structure.

VAMP (Voting Agent Model of Preferences): A computational model of individual multi-attribute choice

This paper proposes an original account of decision anomalies and a computational alternative to existing dynamic models of multi-attribute choice. To date, most models attempting to account for the "Big Three" decision anomalies (similarity, attraction, and compromise effects) are variants of evidence accumulation models, or rational Bayesian analysis. This paper provides an existence proof of a new approach in the form of a multi-agent system based on the principles of voting geometry. Assuming there are a number of neural systems (agents) within an individual's brain, the Big Three decision anomalies can arise as a natural consequence of aggregating preferences across these agents. We operationalize these principles in VAMP, (Voting Agent Model of Preferences), and compare its performance to existing computational models as well as to empirical data. This provides a fundamentally different lens for understanding decision anomalies in multi-attribute choice.

Multialternative decision by sampling: A model of decision making constrained by process data

Sequential sampling of evidence, or evidence accumulation, has been implemented in a variety of models to explain a range of multialternative choice phenomena. But the existing models do not agree on what, exactly, the evidence is that is accumulated. They also do not agree on how this evidence is accumulated. In this article, we use findings from process-tracing studies to constrain the evidence accumulation process. With these constraints, we extend the decision by sampling model and propose the multialternative decision by sampling (MDbS) model. In MDbS, the evidence accumulated is outcomes of pairwise ordinal comparisons between attribute values. MDbS provides a quantitative account of the attraction, compromise, and similarity effects equal to that of other models, and captures a wider range of empirical phenomena than other models.

The comparison process as an account of variation in the attraction, compromise, and similarity effects

Context effects are changes in preference that occur when alternatives are added to a choice set. Models that account for context effects typically assume a within-dimension comparison process; however, the presentation format of a choice set can influence comparison strategies. The present study jointly tests the influence of presentation format on the attraction, compromise, and similarity effects in a within-subjects design. Participants completed a series of choices designed to elicit each of the three context effects, with either a by-alternative or by-dimension format. Whereas the by-alternative format elicited a standard similarity effect, but null attraction and reverse compromise effects, the by-dimension format elicited standard attraction and compromise effects, but a reverse similarity effect. These novel results are supported by a re-analysis of the eye-tracking data collected by Noguchi and Stewart (Cognition, 132(1), 44-56, 2014) and demonstrate that flexibility in the comparison process should be incorporated into theories of preferential choice.

When the Good Looks Bad: An Experimental Exploration of the Repulsion Effect

When people are choosing among different options, context seems to play a vital role. For instance, adding a third option can increase the probability of choosing a similar dominating option. This attraction effect is one of the most widely studied phenomena in decision-making research. Its prevalence, however, has been challenged recently by the tainting hypothesis, according to which the inferior option contaminates the attribute space in which it is located, leading to a repulsion effect. In an attempt to test the tainting hypothesis and explore the conditions under which dominated options make dominating options look bad, we conducted four preregistered perceptual decision-making studies with a total of 301 participants. We identified two factors influencing individuals' behavior: stimulus display and stimulus design. Our results contribute to a growing body of literature showing how presentation format influences behavior in preferential and perceptual decision-making tasks.

The appropriacy of averaging in the study of context effects

Models of human decision-making aim to simultaneously explain the similarity, attraction, and compromise effects. However, evidence that people show all three effects within the same paradigm has come from studies in which choices were averaged over participants. This averaging is only justified if those participants show qualitatively similar choice behaviors. To investigate whether this was the case, we repeated two experiments previously run by Trueblood (Psychonomic Bulletin & Review, 19(5), 962-968, 2012) and Berkowitsch, Scheibehenne, and Rieskamp (Journal of Experimental Psychology, 143(3), 1331-1348, 2014). We found that individuals displayed qualitative differences in their choice behavior. In general, people did not simultaneously display all three context effects. Instead, we found a tendency for some people to show either the similarity effect or the compromise effect but not both. More importantly, many individuals showed strong dimensional biases that were much larger than any effects of context. This research highlights the dangers of averaging indiscriminately and the necessity for accounting for individual differences and dimensional biases in decision-making.