Auditory,visual, and cross-modal negative priming

Auditory, visual, and cross-modal negative priming was investigated using a task in which participants judged whether stimuli were animals or musical instruments. Negative priming was observed, but only if the attended and the ignored primes evoked different responses. This pattern—negative priming after conflict, but not after nonconflict, primes—was demonstrated with visual stimuli and replicated with auditory stimuli, as well as across modalities, both auditory to visual and visual to auditory. Implications for theories of negative priming are discussed.     

The subjective experience of object recognition: comparing metacognition for object detection and object categorization

Perceptual decisions seem to be made automatically and almost instantly. Constructing a unitary subjective conscious experience takes more time. For example, when trying to avoid a collision with a car on a foggy road you brake or steer away in a reflex, before realizing you were in a near accident. This subjective aspect of object recognition has been given little attention. We used metacognition (assessed with confidence ratings) to measure subjective experience during object detection and object categorization for degraded and masked objects, while objective performance was matched. Metacognition was equal for degraded and masked objects, but categorization led to higher metacognition than did detection. This effect turned out to be driven by a difference in metacognition for correct rejection trials, which seemed to be caused by an asymmetry of the distractor stimulus: It does not contain object-related information in the detection task, whereas it does contain such information in the categorization task. Strikingly, this asymmetry selectively impacted metacognitive ability when objective performance was matched. This finding reveals a fundamental difference in how humans reflect versus act on information: When matching the amount of information required to perform two tasks at some objective level of accuracy (acting), metacognitive ability (reflecting) is still better in tasks that rely on positive evidence (categorization) than in tasks that rely more strongly on an absence of evidence (detection).     

Does an attention bias to appetitive and aversive words modulate interference control in youth with ADHD?

Interference control refers to the ability to selectively attend to certain information while ignoring distracting information. This ability can vary as a function of distractor relevance. Distractors that are particularly relevant to an individual may attract more attention than less relevant distractors. This is referred to as attention bias. Weak interference control and altered reward sensitivity are both important features of attention deficit hyperactivity disorder (ADHD). However, interference control is typically studied in isolation. This study integrates both. Youths (aged 9 to 17 years) with ADHD (n = 37, 25 boys) and typically-developing controls (n = 38, 20 boys) completed a Stroop task using appetitive words and matched neutral words to assess whether appetitive distractors diminished interference control more in youths with ADHD than controls. In order to test for specificity, aversive words were also included. As expected, appetitive words disrupted interference control but this effect was not stronger for youths with ADHD than the controls. Aversive words, on the other hand, facilitated interference control. Dimensional analyses revealed that this facilitation effect increased substantially as a function of ADHD symptom severity. Possible mechanisms for this effect include up-regulation of interference control as a function of induced negative mood, or as a function of increased effort. In conclusion, appetitive words do not lead to worse interference control in youths with ADHD compared with controls. Interference control was modulated in a valence-specific manner, concurrent with mood-induced effects on cognitive control.     

Psychological processes in young bullies versus bully‐victims

Some children who bully others are also victimized themselves (“bully‐victims”) whereas others are not victimized themselves (“bullies”). These subgroups have been shown to differ in their social functioning as early as in kindergarten. What is less clear are the motives that underlie the bullying behavior of young bullies and bully‐victims. The present study examined whether bullies have proactive motives for aggression and anticipate to feel happy after victimizing others, whereas bully‐victims have reactive motives for aggression, poor theory of mind skills, and attribute hostile intent to others. This “distinct processes hypothesis” was contrasted with the “shared processes hypothesis,” predicting that bullies and bully‐victims do not differ on these psychological processes. Children (n = 283, age 4–9) were classified as bully, bully‐victim, or noninvolved using peer‐nominations. Theory of mind, hostile intent attributions, and happy victimizer emotions were assessed using standard vignettes and false‐belief tasks; reactive and proactive motives were assessed using teacher‐reports. We tested our hypotheses using Bayesian model selection, enabling us to directly compare the distinct processes model (predicting that bullies and bully‐victims deviate from noninvolved children on different psychological processes) against the shared processes model (predicting that bullies and bully‐victims deviate from noninvolved children on all psychological processes alike). Overall, the shared processes model received more support than the distinct processes model. These results suggest that in early childhood, bullies and bully‐victims have shared, rather than distinct psychological processes underlying their bullying behavior.     

An examination of the construct validity of posttraumatic stress disorder with veterans using a revised criterion set

Ongoing concerns exist in the literature regarding the construct of posttraumatic stress disorder (PTSD) and how to best conceptualize and measure this disorder. We compared the traditional DSM-IV PTSD symptom criteria (i.e., symptoms from clusters B, C, and D) to a revised criterion set that omits overlapping mood and other anxiety symptoms on PTSD prevalence, PTSD diagnostic caseness, associated psychiatric comorbidity, functional status, and structural validity using a cross-sectional, multi-site primary care sample of 747 veterans. After removing items theorized to overlap with mood and other anxiety disorders, PTSD prevalence was identical using both criterion sets (i.e., 12%). Overall, there were few statistically significant differences in PTSD caseness, associated psychiatric comorbidity, functional status, and structural validity across the two diagnostic criterion sets. These data provide further support that removing items that overlap with other psychiatric disorders does not significantly impact the prevalence of PTSD, its associated comorbidity and functional impairment, or its structural validity. Although the revised criterion set represents a more parsimonious model, the current study findings generally support the strong construct validity of PTSD. The implications of these study findings for research and clinical practice are discussed.     

A treadmill and motion coupled virtual reality system for gait training post-stroke.

A virtual reality (VR)-based locomotor training system has been developed for gait rehabilitation post-stroke. The system consists of a self-paced treadmill mounted onto a 6-degrees-of-freedom motion platform. Virtual environments (VEs) that are synchronized with the speed of the treadmill and the motions of the platform are rear-projected onto a screen in front of the walking subject. A feasibility study was conducted to test the capability of two stroke patients and one healthy control to be trained with the system. Three VE scenarios (corridor walking, street crossing, and park stroll) were woven into a gait-training program that provided three levels of complexity (walking speed, slopes, collision avoidances), progression criteria (number of successful trials) and knowledge of results. Results show that, with practice, patients can effectively increase their gait speed as demanded by the task and adapt their gait with respect to the change in physical terrain. However, successful completion of tasks requiring adaptation to increasing demands related to speed and physical terrains does not necessarily predict the patient's ability to anticipate and avoid collision with obstacles during walking. This feasibility study demonstrates that persons with stroke are able to adapt to this novel VR system and be immersed in the VEs for gait training.     

Behavioral trainings and manipulations to reduce delay discounting: A systematic review

In everyday decision-making, individuals make trade-offs between short-term and long-term benefits or costs. Depending on many factors, individuals may choose to wait for larger delayed reward, yet in other situations they may prefer the smaller, immediate reward. In addition to within-subject variation in the short-term versus long-term reward trade-off, there are also interindividual differences in delay discounting (DD), which have been shown to be quite stable. The extent to which individuals discount the value of delayed rewards turns out to be associated with important health and disorder-related outcomes: the more discounting, the more unhealthy or problematic choices. This has led to the hypothesis that DD can be conceptualized as trans-disease process. The current systematic review presents an overview of behavioral trainings and manipulations that have been developed to reduce DD in human participants aged 12 years or older. Manipulation studies mostly contain one session and measure DD directly after the manipulation. Training studies add a multiple session training component that is not per se related to DD, in between two DD task measurements. Ninety-eight studies (151 experiments) were identified that tested behavioral trainings and manipulations to decrease DD. Overall, results indicated that DD can be decreased, showing that DD is profoundly context dependent and changeable. Most promising avenues to pursue in future research seem to be acceptance-based/mindfulness-based trainings, and even more so manipulations involving a future orientation. Limitations and recommendations are discussed to identify the mechanistic processes that allow for changes in discount rate and behavior accordingly.