Erratum: Bonus of rebate?: The impact of income framing on spending and saving

Bonus of Rebate?: The Impact of Income Framing on Spending and Saving. By N. Epley, D. Mak and L. C. Idson (Journal of Behavioral Decision Making, Vol. 19, No. 3, pp. 213–227, 2006). DOI: 10.1002/bdm.519 The above paper was published with an error in the title. The title should read: Bonus or Rebate?: The Impact of Income Framing on Spending and Saving.     

Grasp size and accuracy of approach in reaching

In reaching for an object in the environment, it has been suggested that movement components concerned with transport of the hand toward the object and those related to grasping the object are organized and executed independently. An experiment is reported that demonstrates people adjust grasp aperture to compensate for factors affecting transport error. Grasp aperture was found to be greater in reaching movements performed faster than normal, and grasp aperture was also found to be wider when reaching with the eyes closed. In both cases, transport was spatially less accurate. It is argued that, in advance of movement, formation of grasp is planned to take into account not only the perceived characteristics of the object but, also, internalized information based on past experience about the likely accuracy of the transport component.     

The effect of family variables on child weight change

Previous research has shown that family size, the number of obese persons living at home, and parental weight influence the development of childhood obesity. Our study reports the relevance of these factors to child weight loss during a 1-year treatment period. Multiple linear regression procedures showed that the amount of relative weight change was related to initial treatment success, the number of children in the family, and the gender of the child. Children who were more successful lost more weight initially, had fewer siblings, and were female. These results suggest that family size may interact with treatment to determine weight change. The effects of family size on outcome may be operating simply by reducing the amount of time that a parent has to spend with the child in promoting behavior change. Likewise, increased family size may be operating as a stressor, reducing the effectiveness of parents in effectively managing their children.     

Assessing and reporting the accuracy of position measurements made with optical tracking systems

The use of optical tracking systems to record human movement is now widespread. Although such systems are convenient and potentially very accurate, they must be used carefully to ensure good data. This paper describes the procedures of calibration and reconstruction of position data in cartesian coordinates and suggests steps to maximize their accuracy. Procedures are proposed for characterizing the accuracy of measurement throughout the experimental workspace, and open discussion of the issue by the research community is invited.     

Relation between velocity and curvature in movement: equivalence and divergence between a power law and a minimum-jerk model

Unconstrained hand movements typically display a decrease in hand speed around highly curved sections of a trajectory. It has been suggested that this relation between tangential velocity and radius of curvature conforms to a one-third power law. We demonstrate that a one-third power law can be explained by models taking account of trajectory costs such as a minimum-jerk model. Data were analyzed from 6 subjects performing elliptical drawing movements of varying eccentricities. Conformity to the one-third power law in the average was obtained but is shown to be artifactual. It is demonstrated that asymmetric velocity profiles may result in consistent departures from a one-third power law but that such differences may be masked by inappropriate analysis procedures. We introduce a modification to the original minimum-jerk model by replacing the assumption of a Newtonian point-mass with a visco-elastic body. Simulations with the modified model identify a basis for asymmetry of velocity profiles and thereby predict departures from a one-third law commensurate with the empirical findings.     

Intermittent low-calorie regimen and booster sessions in the treatment of obesity

The present study investigated two new weight-control strategies: an intermittent low-calorie regimen and intermittent scheduling of booster sessions. A new approach to predicting patient weight loss, based on a pretreatment assessment with a highly-structured eating regimen, was also studied. Forty-eight obese patients were randomly assigned to either a Standard Behavioral weight-control condition or to an Intermittent Low-calorie Regimen (< 750 cal for 2 days/week) condition and to one of two maintenance schedules: a Spaced schedule in which the six booster sessions were held at monthly intervals, or a Massed schedule, in which four of the six meetings were held during the third month. Neither the intermittent low-calorie regimen nor the intermittent scheduling of booster sessions significantly affected weight loss. However, weight loss at 1 year was related to compliance to self-monitoring and to self-reported change in eating habits and exercise. In addition, weight loss at 1 year was related to weight loss during the initial pretreatment assessment period.     

The timing of interresponse intervals

Analogs of models of duration discrimination are here related to the timing of discrete motor responses. The measure of interest is the variability in duration of intervals collected in short interval reproduction tasks. For data from a Morse key-tapping task, it is shown that, taken separately, neither of the models described can completely account for the relation between the mean and the variance of the interresponse intervals.