Determinants of following headway in congested traffic

This paper reports on results of a study undertaken in the UK aimed at investigating factors affecting the car following process. An understanding of the factors affecting this complex decision making process is essential to a wide range of theoretical issues including driver workload, capacity and the modeling of freeway flow, as well as practical applications such as the design of in-vehicle driver aids and assistance systems, many of which have direct relevance to increasing driver safety. The study used an instrumented vehicle to collect time dependent following data for a group of test drivers. Data was collected on two differing types of high speed road, using six primary subjects who drove a test vehicle, supplemented by data on 123 drivers that were observed following the test vehicle. Examination was made of how the time headway chosen by a driver is influenced by a range of situational variables commonly believed to effect behavior, with four main findings. Firstly, headway was found to change according to the type of vehicle being followed (i.e. subjects followed closer to trucks than to cars), secondly, little variation was found with changes in overall traffic flow, thirdly, little correlation was found with road type, and lastly a distinct day-to-day variation in individual behavior was observed.     

The effectiveness of feedback in multiple-cue probability learning

How effective are different types of feedback in helping us to learn multiple contingencies? This article attempts to resolve a paradox whereby, in comparison to simple outcome feedback, additional feedback either fails to enhance or is actually detrimental to performance in nonmetric multiple-cue probability learning (MCPL), while in contrast the majority of studies of metric MCPL reveal improvements at least with some forms of feedback. In three experiments we demonstrate that if feedback assists participants to infer cue polarity then it can in fact be effective in nonmetric MCPL. Participants appeared to use cue polarity information to adopt a linear judgement strategy, even though the environment was nonlinear. The results reconcile the paradoxical contrast between metric and nonmetric MCPL and support previous findings of people's tendency to assume linearity and additivity in probabilistic cue learning.     

Cognitively impaired older adults exhibit comparable difficulties on naturalistic and laboratory prospective memory tasks

Prospective memory, or remembering future intentions, is critical for independent living for all ages, but especially older adults. Previous laboratory research has found that cognitively impaired older adults may have particular difficulties with prospective memory, but previous studies have not examined whether these difficulties occur in everyday life. In normal ageing, a dissociation between settings has been observed, with older adults selectively impaired in laboratory (but not naturalistic) contexts. Consequently, in the present study 15 cognitively impaired older adults were compared to demographically matched controls on laboratory and naturalistic measures of prospective memory. The results indicated that the cognitively impaired group performed more poorly on both measures, with the magnitude of the deficit comparable across setting. These results indicate that for older adults who present with cognitive impairment prospective memory deficits observed in laboratory settings may be a valid indicator of difficulties experienced executing delayed intentions in everyday life. Copyright © 2008 John Wiley & Sons, Ltd.     

Choking on the Money: Reward-Based Performance Decrements Are Associated With Midbrain Activity

ABSTRACT— A pernicious paradox in human motivation is the occasional reduced performance associated with tasks and situations that involve larger-than-average rewards. Three broad explanations that might account for such performance decrements are attentional competition (distraction theories), inhibition by conscious processes (explicit-monitoring theories), and excessive drive and arousal (overmotivation theories). Here, we report incentive-dependent performance decrements in humans in a reward-pursuit task; subjects were less successful in capturing a more valuable reward in a computerized maze. Concurrent functional magnetic resonance imaging revealed that increased activity in ventral midbrain, a brain area associated with incentive motivation and basic reward responding, correlated with both reduced number of captures and increased number of near-misses associated with imminent high rewards. These data cast light on the neurobiological basis of choking under pressure and are consistent with overmotivation accounts.     

Using Narrow Facets of an Integrity Test to Predict Safety: A test validation study

This paper describes the development and validation of an integrity test, the WorkKeys Performance Assessment, designed specifically to measure two domains: employee risk reduction (i.e., safety behavior) and general work attitudes. These domains were hypothesized to differentially predict multiple work outcomes, including task performance, organizational citizenship, counterproductive behavior, and safety. The study used a large sample of workers whose performance was rated by their supervisors. Results suggest that both integrity domains predict employee behavior, with risk reduction providing incremental validity over general work attitudes when predicting counterproductive and safety behavior. The findings support the value of measuring both domains of integrity.     

Does Stevens’s Power Law for Brightness Extend to Perceptual Brightness Averaging?

The Psychological Record - Stevens’s power law (Ψ∝Φß) captures the relationship between physical (Φ) and perceived (Ψ) magnitude for many stimulus continua...     

THE EFFECTS OF PARENT‐IMPLEMENTED PECS TRAINING ON IMPROVISATION OF MANDS BY CHILDREN WITH AUTISM

The present study examined the extent to which mothers were able to train their children, 2 boys with autism, to exchange novel pictures to request items using the picture exchange communication system (PECS). Generalization probes assessing each child's ability to mand for untrained items were conducted throughout conditions. Using a multiple baseline design, results demonstrated that both children improvised by using alternative symbols when the corresponding symbol was unavailable across all symbol categories (colors, shapes, and functions) and that parents can teach their children to use novel pictorial response forms.     

The relationship of body dysmorphic disorder and eating disorders to obsessive-compulsive disorder

Body dysmorphic disorder (BDD) and eating disorders are body image disorders that have long been hypothesized to be related to obsessive-compulsive disorder (OCD). Available data suggest that BDD and eating disorders are often comorbid with OCD. Data from a variety of domains suggest that both BDD and eating disorders have many similarities with OCD and seem related to OCD. However, these disorders also differ from OCD in some ways. Additional research is needed on the relationship of BDD and eating disorders to OCD, including studies that directly compare them to OCD in a variety of domains, including phenomenology, family history, neurobiology, and etiology.