Relationships as Commitment Devices: Strategic Silence

People who understand self-control problems can devise mechanisms to overcome them.In this paper, we discuss how relationships can help individuals overcome their selfcontrol problems by creating a tradeoff between desired present procrastination and undesired future procrastination.Threatening not to speak to a person who caves in can create such a tradeoff.The results depend on a limited memory assumption.We show how such interactions can explain strategic pretence, strategic ignorance, why a person would choose to punish himself after he caved in and why punishments need to increase if not adhered to immediately.strategy;bias;behavioural science

Cognitive Procedures and Hyperbolic Discounting

"Hyperbolic discount functions are characterized by a relatively high discount rate over short horizons and a relatively low discount rate over long horizons" (Laibson 1997).We suggest two cognitive procedures where individuals perceive future utility as decreasing at a decreasing rate as a function of time.Such a perception is similar to hyperbolic discounting.The first procedure shows that individuals hyperbolically discount marginal utility from money when they follow a cognitive procedure in which they believe that their wealth might increase or decrease in each future period under the constraint of a perceived small probability that wealth will decrease below its current level.The second procedure shows that individuals hyperbolically discount expected utility from consumption when they believe that they will rationalize their actions and thus alter their utility function over time.The difference in how perceived utility changes over the short and long horizon generates the hyperbolic discounting phenomenon.We find that greater tendencies toward rationalization and greater volatility in consumption increase the hyperbolic discounting phenomenon. Although hyperbolic disc ounting is usually regarded as impulsive and irrational, Azfar (1999) and this author suggest that hyperbolic discounting may be rational in some cases.cognitive process;preferences;bias;rationality;marginalism

A Behavioral Model of Conumption Patterns: The Effects of Cognitive Dissonance and Conformity

Cognitive dissonance causes people to rationalize actions that differ from their own preferences.Conformity, on the other hand, causes people to change their behavior as a result of pressure from others.This paper investigates the consequences of preference dynamic that occur when individuals rationalize their preferences, are conformists and have a minimum consumption constraint.The main results are: (1) Individuals who have a greater tendency toward conformity will rationalize their preferences to a greater degree, (2) Individuals' optimal consumption pattern will be unstable and scatter over time, (3) Average consumption in society will increase along a cyclical path and (4) An increase in either cognitive dissonance or conformity induces greater volatility of average consumption.rationality;cognitive science;consumption;volatility

The role of goal structures and peer climate in trajectories of social achievement goals during high school

Students’ social goals—reasons for engaging in interpersonal relationships with peers—are consequential for students’ interactions with their peers at school and for their well-being. Despite the salience of peer relationships during adolescence, research on social goals is generally lacking compared with academic goals, and it is unknown how these social goals develop over time, especially among high school students. The aim of the study was to assess trajectories of students’ social goals and to determine how relevant individual and contextual variables predicted initial levels and trajectories of students’ social goals. Participants were 9th through 12th grade students (N = 526) attending a U.S. high school. Students filled out surveys of their social goals (social development, social demonstration-approach, and social demonstration-avoidance) 6 times across 2 school years. Nonlinear growth curve analyses and piecewise growth curve analyses were used to assess trajectories of social goals across time. Students’ initial levels of social goals differed based on their gender, grade level, prior achievement, and perceptions of classroom goals structures and peer climate. Furthermore, despite substantial stability over time, the shapes of these goal trajectories were predicted by students’ gender, grade level, and perceptions of classroom goal structures and peer climate. In particular, students who perceived an increase in performance-avoidance classroom goals maintained higher demonstration social goals and decreased in developmental social goals over time, and students who perceived an increase in positive peer climate decreased in demonstration-avoidance social goals. Implications and directions for future research on social goals are discussed

The Role of CP violation in D0 anti-D0 Mixing

In current searches for D0 anti-D0 mixing, the time evolution of ``wrong-sign'' decays is used to distinguish between a potential mixing signal and the dominant background from doubly-Cabibbo-suppressed decays. A term proportional to $\Delta Mt$ in the expression for the time evolution is often neglected in theoretical discussions and experimental analyses of these processes. We emphasize that, in general, this term does not vanish even in the case of CP invariance. Furthermore, CP invariance is likely to be violated if the rate of D0 anti-D0 mixing is close to the experimental bound. The consequence of either of these two facts is that the strongest existing measured bound is not applicable for constraining New Physics.Comment: 14 pages, uuencoded gzip-compressed postscript (84 kB

The leading effect of fluid inertia on the motion of rigid bodies at low Reynolds number

We investigate the influence of fluid inertia on the motion of a finite assemblage of solid spherical particles in slowly changing uniform flow at small Reynolds number, Re, and moderate Strouhal number, Sl. We show that the first effect of fluid inertia on particle velocities for times much larger than the viscous time scales as rootSl Re given that the Stokeslet associated with the disturbance flow field changes with time. Our theory predicts that the correction to the particle motion from that predicted by the zero-Re theory has the form of a Basset integral. As a particular example, we calculate the Basset integral for the case of two unequal particles approaching (receding) with a constant velocity along the line of their centres. On the other hand, when the Stokeslet strength is independent of time, the first effect of fluid inertia reduces to a higher order of magnitude and scales as Re. This condition is fulfilled, for example, in the classical problem of sedimentation of particles in a constant gravity field