Visual control of action without retinal optic flow

In everyday life, the optic flow associated with the performance of complex actions, like walking through a field of obstacles and catching a ball, entails retinal flow with motion energy (first-order motion). We report the results of four complex action tasks performed in virtual environments without any retinal motion energy. Specifically, we used dynamic random-dot stereograms with single-frame lifetimes (cyclopean stimuli) such that in neither eye was there retinal motion energy or other monocular information about the actions being performed. Performance on the four tasks with the cyclopean stimuli was comparable to performance with luminance stimuli, which do provide retinal optic flow. The near equivalence of the two types of stimuli indicates that if optic flow is involved in the control of action, it is not tied to first-order retinal motion.     

Preschoolers' use of surface similarity in object comparisons: taking context into account

Previous research has emphasized the role of within-match similarity in children's comparisons. The current study investigated another potentially important contributing factor, namely the distinctiveness of the matching items relative to other items in the scene. Using a well-known relational mapping task, we found that 3- and 4-year-olds made more correct matches between identical objects when those objects were maximally distinctive from the foils. In a cross-mapping experiment, where same relative size was pitted against object similarity, 3-year-olds made more incorrect object matches when the objects were both similar to each other and distinctive from the foils. Furthermore, 3- and 4-year-olds performed the same, regardless of within-match similarity, so long as the ratios of within-match and nonmatch similarity were roughly equal. These findings suggest that children's comparisons are guided by a ratio consisting of many pairwise similarity relations, including (but not limited to) the degree of within-match similarity.     

Perception of heading without retinal optic flow

How do we determine where we are heading during visually controlled locomotion? Psychophysical research has shown that humans are quite good at judging their travel direction, or heading, from retinal optic flow. Here we show that retinal optic flow is sufficient, but not necessary, for determining heading. By using a purely cyclopean stimulus (random dot cinematogram), we demonstrate heading perception without retinal optic flow. We also show that heading judgments are equally accurate for the cyclopean stimulus and a conventional optic flow stimulus, when the two are matched for motion visibility. The human visual system thus demonstrates flexible, robust use of available visual cues for perceiving heading direction.     

Online Story Comprehension among Children with ADHD: Which Core Deficits are Involved?

Children with ADHD have difficulty understanding causal connections and goal plans within stories. This study examined mediators of group differences in story narrations between children ages 7-9 with and without ADHD, including as potential mediators both the core deficits of ADHD (i.e., inattention, disinhibition, planning/working memory) as well measures of phonological processing and verbal skills. Forty-nine children with ADHD and 67 non-referred children narrated a wordless book and completed tasks assessing the core deficits of ADHD, phonological processing, and verbal skills. Results revealed that, although no shorter than those of non-referred children, the narratives of children with ADHD contained fewer elements relating to the story's causal structure and goal plan. Deficits in sustained attention accounted for the most variance in these differences. Results have implications for understanding and ameliorating the academic problems experienced by children with ADHD.     

Anticipating partners’ responses: Examining item and source memory following interactive exchanges

Within the context of an interactive anagram-solving task, the present studies tested predictions about the role of cognitive anticipation in both source and item memory. After working in pairs to solve anagram problems, participants were surprised by a source-monitoring test focused on the source of solutions (self vs. partner, Experiment 1) or a standard recognition test focused on the solutions themselves (Experiment 2). With the intention of affecting the opportunity to anticipate partners' solutions, two variables were manipulated: anagram difficulty (easy vs. hard) and the delaybetween the presentation of an anagram problem and theprompt tha t designated one member of each pair as the anagram solver. Consistent w i th predictions, asthe opportunity t oanticipate partners'solutions increased, there was a decrease in source accuracy suggesting increased confusion about whether the solution had been self- or partner-generated. Generation-effect failures were observed in item memory. However, these failures reflected increases in item memory for partners' responses rather than decreases in memory for self-generated ones. These studies suggest that when opportunities to anticipate partners' responses are available, self-generative activities may be associated with both self-and partner-generated items, influencing the expression of the generation effect.     

Effects of team and organizational commitment – A longitudinal study

Retention management, i.e., keeping qualified employees, is a top priority for contemporary organizations. Commitment, and especially team commitment, can be the key to mastering this challenge. There is a lack of longitudinal research concerning the development and the direction of the effects of team commitment over time. In a longitudinal field-study design with three points of measurement, a total of 360 employees in 52 semi-autonomous industrial teams were surveyed over a period of three years. On the one hand, organizational commitment showed stronger effects on organization-related criteria (job satisfaction and intention to leave). These effects were consistent over the three points of measurement. Team commitment, on the other hand, affected team-related criteria (team performance and altruism). Longitudinal analyses confirmed the effects of organizational commitment on job satisfaction and intention to leave, and of team commitment on team performance and altruism. Moreover, these effects increased over time. Theoretical and practical implications of these findings are discussed.     

The costs of today’s jobs: Job characteristics and organizational supports as antecedents of negative spillover

This study examined job characteristics and organizational supports as antecedents of negative work-to-nonwork spillover for 1178 U.S. employees. Based on hierarchical regression analyses of 2002 National Study of the Changing Workforce data and O∗NET data, job demands (requirements to work at home beyond scheduled hours, job complexity, time and strain) had positive relationships, and job resources (autonomy and skill development) and organizational supports (flexible work arrangements and two work-life culture facets) had negative relationships to negative spillover, but not all relationships held when multiple predictors were examined. Organizational supports did not moderate relationships of job characteristics to negative spillover, and relative weights analysis indicated that job characteristics accounted for the majority of explained variance in negative spillover. The findings underscore the importance of job characteristics, and suggest that job characteristics and organizational supports both need to be considered when developing work-life policies intended to reduce employees’ negative work-to-nonwork spillover.     

Can Rachman's indirect pathways be used to un-learn fear? A prospective paradigm to test whether children's fears can be reduced using positive information and modelling a non-anxious response

This study investigated whether children's fears could be un-learned using Rachman's indirect pathways for learning fear. We hypothesised that positive information and modelling a non-anxious response are effective methods of un-learning fears acquired through verbal information. One hundred and seven children aged 6-8 years received negative information about one animal and no information about another. Fear beliefs and behavioural avoidance were measured. Children were randomised to receive positive verbal information, modelling, or a control task. Fear beliefs and behavioural avoidance were measured again. Positive information and modelling led to lower fear beliefs and behavioural avoidance than the control condition. Positive information was more effective than modelling in reducing fear beliefs and both methods significantly reduced behavioural avoidance. The results support Rachman's indirect pathways as viable fear un-learning pathways and supports associative learning theories.     

Estimation of a four‐parameter item response theory model

We explore the justification and formulation of a four‐parameter item response theory model (4PM) and employ a Bayesian approach to recover successfully parameter estimates for items and respondents. For data generated using a 4PM item response model, overall fit is improved when using the 4PM rather than the 3PM or the 2PM. Furthermore, although estimated trait scores under the various models correlate almost perfectly, inferences at the high and low ends of the trait continuum are compromised, with poorer coverage of the confidence intervals when the wrong model is used. We also show in an empirical example that the 4PM can yield new insights into the properties of a widely used delinquency scale. We discuss the implications for building appropriate measurement models in education and psychology to model more accurately the underlying response process.