The price of anarchy in social dilemmas: Traditional research paradigms and new network applications

Research on social dilemmas has largely been concerned with whether, and under what conditions, selfish decisions by autonomous individuals jointly result in socially inefficient outcomes. By contrast, considerably less emphasis has been placed on the extent of the inefficiency in those outcomes relative to the social optimum, and how the extent of inefficiency in theory compares with what is observed in experiments or practice. In this expository article, we introduce and subsequently extend the price of anarchy (PoA), an index that originated in studies on communication in computer science, and illustrate how it can be used to characterize the extent of inefficiency in social dilemmas. A second purpose of our article is to introduce a class of social dilemmas that occur when individuals selfishly choose routes in networks, and illustrate how the concept of PoA can be helpful in studying them.     

Motivation for Reading and Middle School Students' Performance on Standardized Testing in Reading

This study examined middle school students' reading motivation and its relations to their performance on a standardized test (ISTEP+) in reading. Participants included 388 sixth- and eighth-grade students from two public middle schools. There were 229 females and 159 males. Participants responded to the Reading Motivation Questionnaire after they had completed the ISTEP+ test. Results showed that students who had high self-efficacy in their reading, read challenging material, and read for aesthetic enjoyment did better on the ISTEP+ test. Students who read mostly for social reasons did poorly on the ISTEP+ test. Grade, gender, and racial differences were found.     

Haptic and Visual Influences on Grasp Point Selection

When using precision grip to pick up objects, there are many possible pairs of grasp points that permit the thumb and index finger to exert opposed forces for secure grip. Previously, it was shown that individuals select grasp points so that the line between them (grasp axis) passes through or near the center of mass (CoM), thus minimizing the torque around the grasp axis during lifting. The accuracy of grasp axis selection depended on object spatial symmetry, indicating the importance of vision. The authors investigated how grasp point selection is influenced by haptic as well as visual information. Ten participants lifted cuboids whose CoM was located either symmetrically in the geometric center or asymmetrically toward one end. Results for the asymmetric cuboid revealed that grasp points migrated toward the asymmetric CoM from the geometric center. This was more pronounced in the presence of visual cues that reliably indicated the location of CoM. The results suggest that grasp point selection is influenced by a multimodal representation of CoM.     

Impaired long-term potentiation and enhanced neuronal excitability in the amygdala of CaV1.3 knockout mice

Previously, we demonstrated that mice in which the gene for the L-type voltage-gated calcium channel Ca_V1.3 is deleted (Ca_V1.3 knockout mice) exhibit an impaired ability to consolidate contextually-conditioned fear. Given that this form of Pavlovian fear conditioning is critically dependent on the basolateral complex of the amygdala (BLA), we were interested in the mechanisms by which Ca_V1.3 contributes to BLA neurophysiology. In the present study, we used in vitro amygdala slices prepared from Ca_V1.3 knockout mice and wild-type littermates to explore the role of Ca_V1.3 in long-term potentiation (LTP) and intrinsic neuronal excitability in the BLA. We found that LTP in the lateral nucleus (LA) of the BLA, induced by high-frequency stimulation of the external capsule, was significantly reduced in Ca_V1.3 knockout mice. Additionally, we found that BLA principal neurons from Ca_V1.3 knockout mice were hyperexcitable, exhibiting significant increases in firing rates and decreased interspike intervals in response to prolonged somatic depolarization. This aberrant increase in neuronal excitability appears to be at least in part due to a concomitant reduction in the slow component of the post-burst afterhyperpolarization. Together, these results demonstrate altered neuronal function in the BLA of Ca_V1.3 knockout mice which may account for the impaired ability of these mice to consolidate contextually-conditioned fear.     

Non‐linear structural equation models with correlated continuous and discrete data

Structural equation models (SEMs) have been widely applied to examine interrelationships among latent and observed variables in social and psychological research. Motivated by the fact that correlated discrete variables are frequently encountered in practical applications, a non‐linear SEM that accommodates covariates, and mixed continuous, ordered, and unordered categorical variables is proposed. Maximum likelihood methods for estimation and model comparison are discussed. One real‐life data set about cardiovascular disease is used to illustrate the methodologies.     

Using the Hands to Identify Who Does What to Whom: Gesture and Speech Go Hand-in-Hand

In order to produce a coherent narrative, speakers must identify the characters in the tale so that listeners can figure out who is doing what to whom. This paper explores whether speakers use gesture, as well as speech, for this purpose. English speakers were shown vignettes of two stories and asked to retell the stories to an experimenter. Their speech and gestures were transcribed and coded for referent identification. A gesture was considered to identify a referent if it was produced in the same location as the previous gesture for that referent. We found that speakers frequently used gesture location to identify referents. Interestingly, however, they used gesture most often to identify referents that were also uniquely specified in speech. Lexical specificity in referential expressions in speech thus appears to go hand-in-hand with specification in referential expressions in gesture.     

The role of spatial integration in the perception of surface orientation with active touch

Vision research has shown that perception of line orientation, in the fovea area, improves with line length (Westheimer & Ley, 1997). This suggests that the visual system may use spatial integration to improve perception of orientation. In the present experiments, we investigated the role of spatial integration in the perception of surface orientation using kinesthetic and proprioceptive information from shoulder and elbow. With their left index fingers, participants actively explored virtual slanted surfaces of different lengths and orientations, and were asked to reproduce an orientation or discriminate between two orientations. Results showed that reproduction errors and discrimination thresholds improve with surface length. This suggests that the proprioceptive shoulder-elbow system may integrate redundant spatial information resulting from extended arm movements to improve orientation judgments.     

Greater emotional empathy and prosocial behavior in late life

Emotional empathy and prosocial behavior were assessed in older, middle-aged, and young adults. Participants watched two films depicting individuals in need, one uplifting and the other distressing. Physiological responses were monitored during the films, and participants rated their levels of emotional empathy following each film. As a measure of prosocial behavior, participants were given an additional payment they could contribute to charities supporting the individuals in the films. Age-related linear increases were found for both emotional empathy (self-reported empathic concern and cardiac and electrodermal responding) and prosocial behavior (size of contribution) across both films and in self-reported personal distress to the distressing film. Empathic concern and cardiac reactivity to both films, along with personal distress to the distressing film only, were associated with greater prosocial behavior. Empathic concern partially mediated the age-related differences in prosocial behavior. Results are discussed in terms of our understanding both of adult development and of the nature of these vital aspects of human emotion. (PsycINFO Database Record (c) 2012 APA, all rights reserved).