Multiple objective programming with piecewise linear functions

An approach to generating all efficient solutions for multiple objective programs with piecewise linear objective functions and linear constraints is presented. The approach is based on the decomposition of the feasible set into subsets, referred to as cells, so that the original problem reduces to a series of single objective linear programs and feasibility tests over the cells. The concepts of cell-efficiency and complex-efficiency are introduced and their relationship with efficiency is examined. A generic algorithm for finding efficient solutions for bi-objective piecewise linear programs is proposed. Applications in location theory as well as in worst case analysis are highlighted. Copyright © 1999 John Wiley & Sons, Ltd.     

Individual differences impact memory for a crime: A study on executive functions resources

Previous studies demonstrated that memory accuracy is affected by the availability of the individual’s cognitive resources. A predominant role in complex cognition has been postulated for executive functions (EF). The aim of the present study was to verify if there are differences in remembering a crime with respect to the individual’s EF availability (i.e., Shifting, Inhibition, and Updating). We showed participants a video of a violent crime. Next, they were requested to imagine to be an eyewitness of the crime and report a testimony as detailed as possible. A subsequent memory test was run after ten days. EF resources were assessed in a third session through three neuropsychological tasks. Findings showed that high EF individuals reported more correct details and fewer memory distortions (i.e., omissions and commissions) than low EF individuals. Our results underline that individual EF resources are implicated in the recalling of an event.     

Experimental consideration of preference in decision making under certainty

This paper describes an experiment in decision making under certainty with multiple, conflicting objectives and continuous decision variables. Two techniques for analysing such problems are considered: one taken from the paradigm of multicriteria decision making (MCDM), a non-directed approach called the NAIVE technique, and one from the paradigm of multiattribute decision analysis (D/A), the SMART technique. While the two techniques seek and are throught to arrive at the same end—a solution which is in some sense optimal for the decision maker (DM)—the former approach implicitly incorporates DM preferences while the latter approach considers preferences explicitly. The setting is a laboratory study using a sample of university students on a three-criteria problem which is designed to study the extent to which value functions implied/assessed by the techniques are consistent with DMs' holistic ranking of alternatives. Results show that (1) the two techniques of interest show significantly better rank order correlation with holistic judgement compared with other techniques, (2) DMs prefer the non-directed MCDM approach and (3) subjects break down into two groups: those that use assessable value functions when ranking and those that do not. This implies that for small-dimensioned problems DMs may first need to be classified as to the assessability of their value functions before a solution method is chosen.     

From terrible twos to sassy sixes: The development of vocabulary and executive functioning across early childhood

Across the early childhood period of development, young children exhibit considerable growth in their executive functioning (EF) and vocabulary abilities. Understanding the developmental trajectory of these seemingly interrelated processes is important as both early vocabulary and EF have been shown to predict critical academic and socio-emotional outcomes later in childhood. Although previous research suggests that EF and vocabulary are correlated in early childhood, much of the existing longitudinal research has focused on unidirectional relations among preschool child samples. The current large-scale study, therefore, sought to examine whether children's vocabulary and EF abilities are bidirectionally related over time across four measurement waves in early childhood (i.e., at ages 2, 3, 4, and 6). At each timepoint, children's vocabulary skills were positively correlated with their concurrent EF abilities. After controlling for child sex and maternal education status, the best-fitting, cross-lagged panel model was a unidirectional model whereby children's early vocabulary scores predicted their later EF performance at each timepoint. Although age 2 EF significantly predicted age 3 vocabulary size, this association was no longer significant after accounting for maternal education status. Our results illustrate that vocabulary size plays an important role in predicting children's later EF performance across various timepoints in early childhood, even after controlling for children's initial EF scores. These findings have important implications for intervention research as fostering early vocabulary acquisition may serve as a possible avenue for improving EF outcomes in young children.

Research Highlights

• Children's vocabulary size is positively correlated with their concurrent executive functioning skill at ages 2, 3, 4, and 6
• Young children's early vocabulary scores predict their later EF performance across measurement waves, even after controlling for initial EF skill
• There is stability in children's relative vocabulary size and executive functioning performance over time in early childhood