Time-varying decision boundaries: insights from optimality analysis

The most widely used account of decision-making proposes that people choose between alternatives by accumulating evidence in favor of each alternative until this evidence reaches a decision boundary. It is frequently assumed that this decision boundary stays constant during a decision, depending on the evidence collected but not on time. Recent experimental and theoretical work has challenged this assumption, showing that constant decision boundaries are, in some circumstances, sub-optimal. We introduce a theoretical model that facilitates identification of the optimal decision boundaries under a wide range of conditions. Time-varying optimal decision boundaries for our model are a result only of uncertainty over the difficulty of each trial and do not require decision deadlines or costs associated with collecting evidence, as assumed by previous authors. Furthermore, the shape of optimal decision boundaries depends on the difficulties of different decisions. When some trials are very difficult, optimal boundaries decrease with time, but for tasks that only include a mixture of easy and medium difficulty trials, the optimal boundaries increase or stay constant. We also show how this simple model can be extended to more complex decision-making tasks such as when people have unequal priors or when they can choose to opt out of decisions. The theoretical model presented here provides an important framework to understand how, why, and whether decision boundaries should change over time in experiments on decision-making.     

Extending Models of Prosocial Behavior to Explain University Alumni Contributions1

Survey data merged with contribution records from a development office database provided a basis for understanding alumni support for a university. The survey randomly sampled alumni of a state university school of management who had graduated between 1980 and 1988. Subjects filled out mail questionnaires measuring social psychological constructs from the literature on prosocial behavior. The determinants of obligation to donate included perceived efficacy, perceived need, reciprocity, and individual attachment to the university. Obligation and other constructs explained the number of donations recorded in the development office database over 6 years. The model also predicted intentions to support the university by working for an alumni association or attending reunions. This model of alumni donation leads to recommendations for designing university fund-raising communications.     

Consumer recycling: role of incentives,information, and social class

• More and more communities have instituted recycling programs and consumer recycling is no longer a new fad; it is here to stay. However, consumer commitment to recycling and participation rates have leveled off. Whereas lack of access to recycling facilities was cited as a key inhibitor to participation in the early days of recycling, that is generally not the case anymore. Thus there is an imperative to revisit consumer recycling by focusing on behavioral issues that reflect today's context. In this study we review the past literature and propose a comprehensive model of consumer recycling. We identify two intervention mechanisms – incentives or information – that are believed to increase recycling participation. We, then, describe a longitudinal field experiment to evaluate the relative merits of these intervention programs. We conclude that either intervention program is effective, although informational programs appear to have more long‐term effects than incentive programs. We also create a new measure of social class, one that includes other influential actors' characteristics, and show its relationship to recycling attitudes and behaviors.

Copyright © 2007 John Wiley & Sons, Ltd.     

The G-NORM Scale: Development and Validation of a Theory-Based Gender Norms Scale

Sex Roles - Gender norms are increasingly recognized as important modifiers of health. Despite growing awareness of how gender norms affect health behavior, current gender norms scales are often...     

Use of the Risk Perception Attitude Framework for Promoting Breast Cancer Prevention

The risk perception attitude (RPA) framework classifies people into 4 groups based on their perceptions of risk and personal efficacy: responsive (high risk, high efficacy), avoidance (high risk, low efficacy), proactive (low risk, high efficacy), and indifference (low risk, low efficacy). This study tested the central propositions from the RPA framework among a group of immigrant Indian women (N = 413) in the Washington, DC area in their propensity to pay attention to breast cancer information and engage in self‐exams and clinical screening. Self‐efficacy and knowledge about breast cancer were consistent predictors of these outcomes. Use of the RPA framework explained 16% to 27% of the variance. Implications for breast cancer prevention campaigns are discussed.     

Online feedback and the regulation of degrees of freedom in motor control

We tested the hypothesis that the degree to which online feedback is used to control movement influences the regulation of degrees of freedom in a task. Ten participants performed an isometric force production task with their two index fingers with the goal of matching the total force to a target waveform. The role of online feedback was manipulated by changing three factors - the tracking mode, the profile of the target waveform, and the visual gain. The results showed that the coupling between the finger forces was lower in conditions where participants used online feedback to correct their movements compared to conditions where more feedforward strategies were used. The availability of online feedback is dependent on the nature of the task and this contributes to task-dependent changes in the regulation of the degrees of freedom.