The Phantom Decoy Effect in Perceptual Decision Making

Male attractiveness is subjective to exposure to males of different attractiveness in fruit flies

Mate choice is a crucial decision in any animal. In terms of fitness, the best mate is the one that leads to the most abundant and productive offspring. Pairing with a low-quality mate would reduce fitness, generating selection for accurate and subtle mate choice in all animal species. Hence, mate choice is expected to be highly context dependent, and should depend on other potential options. For instance, a medium-quality male can constitute the best option when all other males are in poorer condition, but not when there are better-quality males available. Therefore, animals are predicted to gather information about their social context and adapt their mate choice to it. Here, we report on experiments in which we manipulated the social environment of females of Drosophila melanogaster and found that after encountering a high or a low-quality male, they take more or less time to accept copulation with another male, suggesting that females adapt their mating strategy to their social context. We also report on a similar effect in D. biarmiceps. Thus, male attractiveness appears to depend on the quality of recently met males, suggesting that male attractiveness is subjective, indicating plastic and context dependent mate choice.

An investigation into the influence of context effects on crowd exit selection under gender difference in indoor evacuation

Introduction

Exit selection is crucial in indoor emergency evacuation. Domestic and foreign scholars have found that exit choice behavior is influenced by three factors: environmental factors, social interactions, and individual internal factors. Previous studies have shown that in addition to a single environmental factor affecting exit decisions, the influence of other available exit options in the context can ultimately lead to a reversal of exit decisions -The context effect. However, the impact of context effects on exit decisions in emergency situations has not been thoroughly explored. Therefore, this article identifies three basic independent variables: context effects, crowd flows, and gender differences, to study the exit decisions of different gender groups facing different crowd flows, as well as how context effects affect existing exit decisions.

Methods

In this paper, we used virtual reality technology to construct an indoor fire scene and designed a total of 15 virtual experiments with different crowd distribution or context effects. 131 participants were divided into two groups, male and female, and their exit decisions were observed under different crowd flows and contextual effects.

Results

The research results show that: 1) Both men and women have an innate preference to avoid crowded exits, and the proportion of following crowd evacuation significantly decreases when there are crowded crowds in the scene; 2) The exit decisions of female participants are more influenced by the crowd, while men tend to be more influenced by context effects when evacuating independently; 3) The context effects on exit decisions in emergency situations is statistically significant, and this performance is more significant in the male population. Further analysis reveals that similarity effects have a more significant impact on exit decisions than attraction effects.

Discussions

These findings provide deeper insights into the exit choice behavior of the population and may contribute to the design of safe exits in indoor buildings. In addition, this article emphasizes the importance of context effects and provides a foundation for future research.

To eat, or not to eat: a phantom decoy affects information-gathering behavior by a free-ranging mammalian herbivore

When foraging, making appropriate food choices is crucial to an animal's fitness. Classic foraging ecology theories assume animals choose food of greatest benefit based on their absolute value across multiple dimensions. Consequently, poorer options are considered irrelevant alternatives that should not influence decision-making among better options. But heuristic studies demonstrate that irrelevant alternatives (termed decoys) can influence the decisions of some animals, indicating they use a relative rather than absolute evaluation system. Our aim was to test whether a decoy influenced the decision-making process-that is, information-gathering and food choice-of a free-ranging mammalian herbivore. We tested swamp wallabies, Wallabia bicolor, comparing their behavior toward, and choice of, two available food options over time in the absence or presence of the decoy. We used a phantom decoy-unavailable option-and ran two trials in different locations and seasons. Binary preferences (decoy absent) for the two available food options differed between trials. Irrespective of this difference, across both trials the presence of the decoy resulted in animals more likely to overtly investigate available food options. But, the decoy only shifted food choice, weakly, in one trial. Our results indicate that the decoy influenced the information-gathering behavior during decision-making, providing the first evidence that decoys can affect decision-making process of free-ranging mammalian herbivores in an ecologically realistic context. It is premature to say these findings confirm the use of relative evaluation systems. Whether the foraging outcome is more strongly affected by other decoys, food dimensions, or ecological contexts, is yet to be determined.

The Attraction Effect in Crowdfunding

Crowdfunding has reached enormous popularity among entrepreneurs, yet many struggle to fund their projects. For example, only 39.8% of all Kickstarter projects get funded. Why? Entrepreneurs need to set a predefined funding goal, which needs to be reached to get the project funded. If not reached, they do not get the money. To reach the funding goal, entrepreneurs can design reward menus from which backers can choose low-priced to high-priced rewards to support a given project. We show that simply inserting a so-called decoy option—an option in the first place that does not make sense but makes higher-priced options more attractive—can lead to significantly more backers choosing a high-priced option (up to 28% more high-priced choices). This makes it more likely for entrepreneurs to reach their predefined funding goals and thus start their designated projects.

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.

Category Congruence of Display-Only Products Influences Attention and Purchase Decisions

In e-commerce settings, shoppers can navigate to product-specific pages on which they are asked to make yes-or-no decisions about buying a particular item. Beyond that target, there are often other products displayed on the page, such as those suggested by the retailers' recommendation systems, that can influence consumers' buying behavior. We propose that display items that come from the same category as the target product (matched) may enhance target purchase by increasing the attractiveness of the presented opportunity. Contrasting this, mismatched display items may reduce purchase by raising awareness of opportunity costs. Eye-tracking was used to explore this framework by examining how different types of displays influenced visual attention. Although target purchase rates were higher for products with matched vs. mismatched displays, there was no difference in fixation time for the target images. However, participants attended to mismatched display items for more time than they did for matched ones consistent with the hypothesized processes. In addition, increases in display attractiveness increased target purchase, but only for matched items, in line with supporting the target category. Given the importance of relative attention and information in determining the impact of display items, we replicated the overall purchase effect across varying amounts of available display information in a second behavioral study. This demonstration of robustness supports the translational relevance of these findings for application in industry.

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.

How do insects choose flowers? A review of multi-attribute flower choice and decoy effects in flower-visiting insects

Understanding why animals (including humans) choose one thing over another is one of the key questions underlying the fields of behavioural ecology, behavioural economics and psychology. Most traditional studies of food choice in animals focus on simple, single-attribute decision tasks. However, animals in the wild are often faced with multi-attribute choice tasks where options in the choice set vary across multiple dimensions. Multi-attribute decision-making is particularly relevant for flower-visiting insects faced with deciding between flowers that may differ in reward attributes such as sugar concentration, nectar volume and pollen composition as well as non-rewarding attributes such as colour, symmetry and odour. How do flower-visiting insects deal with complex multi-attribute decision tasks? Here we review and synthesise research on the decision strategies used by flower-visiting insects when making multi-attribute decisions. In particular, we review how different types of foraging frameworks (classic optimal foraging theory, nutritional ecology, heuristics) conceptualise multi-attribute choice and we discuss how phenomena such as innate preferences, flower constancy and context dependence influence our understanding of flower choice. We find that multi-attribute decision-making is a complex process that can be influenced by innate preferences, flower constancy, the composition of the choice set and economic reward value. We argue that to understand and predict flower choice in flower-visiting insects, we need to move beyond simplified choice sets towards a view of multi-attribute choice which integrates the role of non-rewarding attributes and which includes flower constancy, innate preferences and context dependence. We further caution that behavioural experiments need to consider the possibility of context dependence in the design and interpretation of preference experiments. We conclude with a discussion of outstanding questions for future research. We also present a conceptual framework that incorporates the multiple dimensions of choice behaviour.

Attraction comes from many sources: Attentional and comparative processes in decoy effects

The attraction effect emerges when adding a seemingly irrelevant option (decoy) to a binary choice shifts preference towards a target option. This suggests that choice behaviour is dynamic, i.e., choice values are developed during deliberation, rather than manifesting some pre-existing preference set. Whereas several models of multialternative and multiattribute decision making consider dynamic choice processes as crucial to explain the attraction effect, empirically investigating the exact nature of such processes requires complementing choice output with other data. In this study, we focused on asymmetrically dominated decoys (i.e., decoys that are clearly dominated only by the target option) to examine the attentional and comparative processes responsible for the attraction effect. Through an eye-tracker paradigm, we showed that the decoy option can affect subjects’ preferences in two different and not mutually exclusive ways: by focusing the attention on the salient option and the dominance attribute, and by increasing comparisons with the choice dominant pattern. Although conceptually and procedurally distinct, both pathways for decoy effects produce an increase in preferences for the target option, in line with attentional and dynamic models of decision making. Eye-tracking data provide further details to the verification of such models, by highlighting the context-dependent nature of attention and the development of similarity-driven competitive decisional processes.

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.

The impact of phantom decoys on the neural processing of valuation

Rational decision theories posit that good choices should be based solely on information that is relevant to the choice at hand. However, introducing an inferior option that would never be chosen can influence choices among other relevant options, known as decoy effect. We used functional magnetic resonance imaging (fMRI) combined with a simple gambling task to investigate the neural signature of decision-making in or against the influence of the decoy effect in inferior and superior phantom decoy conditions. The fMRI results show that compared with choosing against the influence of the dominated phantom inferior option, choosing in the influence of the same option was associated with stronger activation in bilateral caudate and weaker functional connectivity between the left ventral anterior cingulate cortex (vACC) and the left caudate. Phantom inferior effect selectively enhanced the connectivity from the caudate to the vACC but not vice versa. Choosing in the influence of the dominated phantom superior option engaged greater activity in the left dorsal ACC and stronger functional connectivity between the left dACC and bilateral anterior insula. Furthermore, the direction of the phantom superior effect was restricted from left dACC to the anterior insula, but not vice versa. Our findings suggest that a phantom inferior decoy may boost the value of the target via the reward network, whereas a phantom superior decoy may diminish the value of the target option via the aversion network. Our study provides neural evidence to support that valuation is context dependent and delineates differential neural networks underlying the influence of unavailable inferior and superior decoy options on our decision-making.

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.

'Three is better than two': Increasing donations with the attraction effect

Five experiments (N_total  = 2,503) tested the attraction effect and its boundary conditions in the context of helping behaviour. Participants could choose one donation appeal in a set of either two or three alternatives. The three alternatives set included a decoy - an alternative that resembled but was clearly inferior to a target (i.e., the most beneficial) alternative. A clear and consistent pattern emerged: Participants chose the target alternative more frequently and perceived it as more beneficial (and somewhat less costly) when the decoy was present compared to when it was absent. This finding was robust when the attribute ratings of the alternatives were unclear, when the target alternative offered a bundle of unrelated products, and when participants could refrain from donating altogether, or contribute any amount they wished. Our findings offer concrete and simple strategies that charities can implement at zero cost to increase giving and the perceived benefits that people's good deed bring about to those in need.

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.

Indulgent Foods Can Paradoxically Promote Disciplined Dietary Choices

As obesity rates continue to rise, interventions promoting healthful choices will become increasingly important. Here, participants ( N = 79) made binary choices between familiar foods; some trials contained a common consequence that had a constant probability of receipt regardless of the participant's choice. We theorized-on the basis of simulations using a value-normalization model-that indulgent common consequences potentiated disciplined choices by shaping other options' perceived healthfulness and tastiness. Our experimental results confirmed these predictions: An indulgent common consequence more than doubled the rate of disciplined choices. We used eye-gaze data to provide insights into the underlying mechanisms, finding that an indulgent common consequence biased eye gaze toward healthful foods. Furthermore, attention toward the common consequence predicted individual differences in behavioral bias. Results were replicated across two independent samples receiving distinct goal primes. These results demonstrate that introducing an irrelevant indulgent food can alter processing of healthier items-and thus promote disciplined choices.

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.