Trial-by-trial updating of an internal reference in discrimination tasks: Evidence from effects of stimulus order and trial sequence

In psychophysics, participants are often asked to discriminate between a constant standard and a variable comparison. Previous studies have shown that discrimination performance is better when the comparison follows, rather than precedes, the standard. Prominent difference models of psychophysics and decision making cannot easily explain this order effect. However, a simple extension of this model class involving dynamical updating of an internal reference accounts for this order effect. In addition, this Internal Reference Model (IRM) predicts sequential response effects. We examined the predictions of IRM in two duration discrimination experiments. The obtained results are in agreement with the predictions of IRM, suggesting that participants update their internal reference on every trial. Additional simulations show that IRM also accounts for the negative sequential effects observed in single-stimulus paradigms.     

Teaching Fourth and Fifth Graders to Evaluate Information Sources During Text Comprehension

In two experiments, we examined fourth and fifth graders' comprehension of the source of information in texts presenting controversial issues. In Experiment 1, participants read short texts in which two people presented different arguments regarding an issue. Participants identified who said what and evaluated each source's knowledge of the issue. Most students correctly identified the source of information but failed to take into account each source's characteristics when determining who was most knowledgeable. In Experiment 2, we implemented an intervention on students' evaluations of information sources. Less skilled students in the intervention group assessed source knowledge more accurately than those in a control group. We conclude that elementary school students' comprehension of who says what in a text can benefit from training sessions that involve practice, feedback, explanations, and discussions. We consider the implications for document-based learning in elementary and secondary education.     

Increasing Accuracy of Video Quality Ratings through Direction of Attention and Training

This paper describes the results of two studies undertaken to better understand the strong positive relationship between the content of a video clip and viewers' subjective ratings of the video quality of that clip. Experiment 1 evaluated the effect of training on video quality ratings. Experiment 2 assessed the impact of attention in these assessments. Experiment 1 showed that training participants on video quality assessment techniques removed viewers' heuristic reliance on affect while increasing accuracy. Experiment 2 demonstrated that participants' video quality ratings could also be improved by directing their focus of attention. Focusing viewers on quality did not show a moderation of the relationship between content immersion and video quality, as participants maintained high levels of content immersion even when focusing on video quality. Because training and attention increased quality rating accuracy, they could be utilized in video quality testing to improve the viewer feedback received. Copyright © 2013 John Wiley & Sons, Ltd.     

MOTOR PREPARATION,MOTOR EXECUTION,ATTENTION, AND EXECUTIVE FUNCTIONS IN ATTENTION DEFICIT/HYPERACTIVITY DISORDER (ADHD)

Attention and executive functions were investigated in medicated and unmedicated children with ADHD combined type using a novel selective reaching task. This task involved responding as rapidly as possible to a target while at times having to ignore a distractor. Results indicated that unmedicated children with ADHD showed slow and inaccurate responding. Slow responding reflected problems at the stage of movement preparation but not movement execution. An attentional impairment, rather than a motor planning problem per se, appeared to underlie the slow movement preparation. Inaccurate responding reflected problems with response inhibition and selective attention, impulsivity, set-shifting, and difficulties in maintaining vigilance. Although medicated children with ADHD did not show slow movement preparation, they did show some response inaccuracy, resulting especially from impulsive responding.These findings suggest that ADHD is characterized by slow motor preparation (but not motor execution), and deficits in selective attention, vigilance, and executive functions. Preliminary results suggest that stimulant medication may resolve some of these motor, attentional and executive function deficits.     

Posttraumatic Stress Symptoms and Perceived Relationship Safety as Predictors of Dyadic Adjustment: A Test of Mediation and Moderation

The purpose of this study was to examine the predictive value of PTSD symptoms and perceived relationship safety on dyadic adjustment. Participants included 390 individuals who were in a committed romantic relationship. Data were gathered from two populations; clients of a university-based family therapy clinic (n = 132), and community respondents to an announcement on a large university's electronic bulletin board (n = 258). Structural equation modeling was used to test a model of mediation, as well as multiple group analysis to test for moderation by setting (clinical vs. community) and gender. Results indicated that perceived relationship safety fully mediated the relationship between PTSD symptoms and dyadic adjustment. Gender moderated the relationships in the model, but no differences were found between the clinical and community samples. Findings suggest the importance of addressing experiences of safety and security in relationships, as these may be of particular importance for those who have experienced trauma.     

Posture-movement responses to stance perturbations and upper limb fatigue during a repetitive pointing task

Localized muscle fatigue and postural perturbation have separately been shown to alter whole-body movement but little is known about how humans respond when subjected to both factors combined. Here we sought to quantify the kinematics of postural control and repetitive upper limb movement during standing surface perturbations and in the presence of fatigue. Subjects stood on a motion-based platform and repetitively reached between two shoulder-height targets until noticeably fatigued (rating of perceived exertion = 8/10). Every minute, subjects experienced a posterior and an anterior platform translation while reaching to the distal target. Outcomes were compared prior to and with fatigue (first vs. final minute data). When fatigued, regardless of the perturbation condition, subjects decreased their shoulder abduction and increased contralateral trunk flexion, a strategy that may relieve the load on the fatiguing upper limb musculature. During perturbations, kinematic adaptations emerged across the trunk and arm to preserve task performance. In contrast to our expectation, the kinematic response to the perturbations did not alter in the presence of fatigue. Kinematic adaptations in response to the perturbation predominantly occurred in the direction of the reach whereas fatigue adaptations occurred orthogonal to the reach. These findings suggest that during repetitive reaching, fatigue and postural perturbation compensations organize so as to minimize interaction with each other and preserve the global task characteristics of endpoint motion.     

Vertical and leg stiffness and stretch-shortening cycle changes across maturation during maximal sprint running

The purpose of this study was to investigate whether vertical and leg stiffness, and stretch-shortening cycle (SSC) ability differed in developing athletes of various maturity status during maximal sprint running. Seventy-four male participants between 8 and 16 years of age were categorized into pre-, mid- or post-peak height velocity (PHV) and sprinted for 30 meters on a non-motorized treadmill. Dimensionless vertical stiffness increased significantly (p < .05) from pre-, to mid- and post-PHV state, while dimensionless leg stiffness was significantly higher in post- compared to mid- (18.4%) and pre-PHV participants (44.5%). Eccentric power was significantly lower in pre- compared to the mid- and post-PHV participants. Concentric power increased from pre- to mid- and post-PHV state. An analysis of covariance revealed no significant differences between all groups in dimensionless vertical and leg stiffness, eccentric and concentric time and power when controlling for years from PHV (maturation). Eccentric or concentric power, were found to be the best predictors of maximum velocity across all maturation groups (r² = .37–.68). It seems that maturation affects the ability to absorb and produce power and furthermore these variables are important predictors of maximal running velocity.     

Culturally Competent Family Therapy with Latino/Anglo-American Adolescents: Facilitating Identity Formation

On two occasions separated by one year, Chinese adolescents (N = 2,758) responded to instruments measuring their perceived parent-adolescent trust (i.e., paternal trust of the child and the child's trust of the parent) and other dimensions of parent-child relational qualities (satisfaction with parental control, readiness to communicate with the parent, and global satisfaction with the parent-child relationship). Results showed that perceived parent-adolescent trust was concurrently and longitudinally related to other dimensions of parent-child relational qualities. Multiple regression analyses suggest that the relations between perceived parent-adolescent trust and different dimensions of parent-child relational qualities over time were bidirectional in nature. Relative to perceived paternal trust of the adolescent child, adolescent child's trust of their parents exerted a stronger influence on different dimensions of parent-adolescent relational qualities, particularly in the father-adolescent dyad. While the influence of the child's readiness to communicate with the parents on parent-adolescent trust was weak in the father-adolescent dyad, the influence of global satisfaction with the parent-adolescent relationship on parent-adolescent trust was weak in the mother-adolescent dyad. The implications of the present findings on parent education and family therapy are discussed.     

The implicit self and the specificity-matching principle: Implicit self-concept predicts domain-specific outcomes

According to the specificity-matching principle (Swann, Chang-Schneider, & McClarty, 2007), specific aspects of self-concept should predict domain specific outcomes, rather than broader outcomes. The purpose of the current study was to determine whether this principle, which has thus far been examined using explicit measures of the self, extends to the implicit self-concept. We tested this idea in the domain of math achievement. We observed that explicit math self-concept was correlated with specific outcomes (measures of math achievement), whereas explicit self-esteem was correlated with a broad outcome (satisfaction with life). Thus, we replicated the specificity-matching principle using explicit measures of self-esteem and self-concept. Moreover, we found that implicit self-concept was correlated with domain-specific outcomes, but not a global outcome, as the specificity-matching principle would predict. Furthermore, regression analyses indicated that implicit self-concept accounted for unique variance in the domain-specific outcomes, for which the other measures of the self could not account. Taken together, we conclude that the specificity-matching principle does indeed extend to the implicit self-concept.