The utilization of visual information in the control of rapid sequential aiming movements.

Two experiments were conducted to examine the role of vision in the execution of a movement sequence. Experiment 1 investigated whether individual components of a sequential movement are controlled together or separately. Participants executed a rapid aiming movement to two targets in sequence. A full vision condition was compared to a condition in which vision was eliminated while in contact with the first target. The size of the first target was constant, while the second target size was varied. Target size had an influence on movement time and peak velocity to the first target. Vision condition and target size did not affect the time spent on the first target. These results suggest that preparation of the second movement is completed before the first movement is terminated. Experiment 2 examined when this preparation occurred. A full vision condition was compared to a condition in which vision was occluded during the flight phase of the first movement. Movement initiation times were shorter when vision was continually available. Total movement time was reduced with vision in two-target condition, but not in a control one-target condition. The time spent on the first target was greater when vision was not available during the first movement component. The results indicate that vision prior to movement onset can be used to formulate a movement plan to both targets in the sequence [Fischman & Reeve (1992).     

The role of impulse variability in manual-aiming asymmetries

Summary Two experiments are reported in which we examined the hypothesis that the advantage of the right hand in target aiming arises from differences in impulse variability. Subjects made aiming movements with the left and right hands. The force requirements of the movements were manipulated through the addition of mass to the limb (Experiments 1 and 2) and through control of movement amplitude (Experiment 1). Although the addition of mass diminished performance (i. e., it increased movement times in Experiment 1 and increased error in Experiment 2), the two hands were not differently affected by the manipulation of required force. In spite of the fact that the right hand exhibited enhanced performance (i. e., lower movement times in Experiment 1 and greater accuracy in Experiment 2), these advantages were not reflected in kinematic measures of impulse variability.We are grateful to an anonymous reviewer for clarification of this distinction.     

Comparing the CASI-4R and the PGBI-10 M for Differentiating Bipolar Spectrum Disorders from Other Outpatient Diagnoses in Youth

We compared 2 rating scales with different manic symptom items on diagnostic accuracy for detecting pediatric bipolar spectrum disorder (BPSDs) in outpatient mental health clinics. Participants were 681 parents/guardians of eligible children (465 male, mean age = 9.34) who completed the Parent General Behavior Inventory-10-item Mania (PGBI-10 M) and mania subscale of the Child and Adolescent Symptom Inventory-Revised (CASI-4R). Diagnoses were based on KSADS interviews with parent and youth. Receiver operating characteristic (ROC) analyses and diagnostic likelihood ratios (DLRs) determined discriminative validity and provided clinical utility, respectively. Logistic regressions tested for incremental validity in the CASI-4R mania subscale and PGBI-10 M in predicting youth BPSD status above and beyond demographic and common diagnostic comorbidities. Both CASI-4R and PGBI-10 M scales significantly distinguished BPSD (N = 160) from other disorders (CASI-4R: Area under curve (AUC) = .80, p < 0.0005; PGBI-10 M: AUC = 0.79, p < 0.0005) even though scale items differed. Both scales performed equally well in differentiating BPSDs (Venkatraman test p > 0.05). Diagnostic likelihood ratios indicated low scores on either scale (CASI: 0–5; PGBI-10 M: 0–6) cut BPSD odds to 1/5 of those with high scores (CASI DLR- = 0.17; PGBI-10 M DLR- = 0.18). High scores on either scale (CASI: 14+; PGBI-10 M: 20+) increased BPSD odds about fourfold (CASI DLR+ = 4.53; PGBI-10 M DLR+ = 3.97). Logistic regressions indicated the CASI-4R mania subscale and PGBI-10 M each provided incremental validity in predicting youth BPSD status. The CASI-4R is at least as valid as the PGBI-10 M to help identify BPSDs, and can be considered as part of an assessment battery to screen for pediatric BPSDs.     

The relations of parental autonomy support to cultural internalization and well-being of immigrants and sojourners

Previous research has demonstrated that autonomy support is one particularly effective means of promoting internalization and fostering well-being. The present study sought to determine if this would also be the case with regards to culture by testing the relation of perceived parental autonomy support to the cultural internalization and well-being of multicultural students. In Study 1, 105 multicultural participants living in Canada were more likely to have fully internalized their host and heritage cultures and to have higher self-reported well-being when they reported that their parents were autonomy supportive. In Study 2, 125 Chinese-Malaysians sojourners were also more likely to have fully internalized their heritage culture and indicated higher well-being when they perceived their parents as autonomy supportive. In both studies, heritage cultural internalization was also associated with higher well-being.     

Risk avoidance: Graphs versus numbers

There have long been speculations that graphical and numerical presentations of risk statistics differ in their impact on people’s willingness to pursue actions that could harm or even kill them. But research has been unclear about the processes whereby the pictorial character of graphical displays per se might affect those risky decisions or even whether such effects actually occur. In two studies, we demonstrate that the pictorial nature of a graphical risk display can, indeed, increase risk avoidance. This increase is associated with a heightened impression of the riskiness of less safe alternatives. The results suggest that this picture-driven, intensified sense of riskiness, in turn, rests on two kinds of mechanisms: one cognitive, the other affective. Cognitively, pictorial presentations impose weaker upper bounds on people’s internal representations of the chances that riskier alternatives will bring about actual harm. Affectively, pictures ignite stronger, more aversive negative associations with riskier options and their outcomes.     

Functional and connectivity changes during working memory in Huntington’s disease: 18 month longitudinal data from the IMAGE-HD study

Background

This study aimed to characterize, for the first time, 18 month longitudinal changes in both functional activation and functional connectivity during working memory in premanifest Huntington’s disease (pre-HD) and symptomatic HD (symp-HD).

Methods

Functional magnetic resonance imaging (fMRI) was used to investigate longitudinal changes in neuronal activity during working memory performance via an N-BACK task (0-BACK and 1-BACK) in 27 pre-HD, 17 symp-HD, and 23 control participants. Whole-brain analysis of activation and region-of-interest analysis of functional connectivity was applied to longitudinal fMRI data collected at baseline and 18 months follow-up.

Results

Compared with controls, the pre-HD group showed significantly increased activation longitudinally during 1-BACK versus 0-BACK in the lateral and medial prefrontal, anterior cingulate, primary motor, and temporal areas cortically, and caudate and putamen subcortically. Pre-HD far from onset, compared with controls, showed further longitudinal increases in the right and left dorsolateral prefrontal cortex (DLPFC). Longitudinal increased activation in anterior cingulate and medial primary motor areas were associated with disease burden in the pre-HD group. Moreover, in pre-HD increased activation over time in primary motor and putamen regions were associated with average response time during 1-BACK performance. During 1-BACK, functional connectivity between the right DLPFC and posterior parietal, anterior cingulate, and caudate was significantly reduced over 18 months only in the pre-HD group.

Conclusions

Longitudinal reductions in connectivity over 18 months may represent an early signature of cortico-cortical and cortico-striatal functional disconnectivity in pre-HD, whereas the concomitant increased cortical and subcortical activation may reflect a compensatory response to the demands for cognitive resources required during task performance. Our findings demonstrate that functional imaging modalities have the potential to serve as sensitive methods for the assessment of cortical and subcortical responses to future treatment measures.     

Attentional capture by onsets and offsets

Three experiments were conducted to examine whether human infants would form a categorical representation for the spatial relation between. Experiment 1 showed that 6- and 7-month-olds familiarized with stimuli depicting a diamond in different locations between two reference bars subsequently preferred a stimulus displaying the diamond located outside the bars over a stimulus displaying the diamond located in a novel position between the bars. Experiments 2 and 3 revealed that this preference could not be attributed to a failure to discriminate the location changes of the diamond between the bars or an a priori preference. The overall pattern of results indicates that 6- and 7-month-olds had formed a categorical representation for between. The findings are discussed in terms of factors affecting development of categorical representations for spatial relation information.     

Evidence for a response preparation bottleneck during dual-task performance: Effect of a startling acoustic stimulus on the psychological refractory period

The present study was designed to investigate the mechanism associated with dual-task interference in a psychological refractory period (PRP) paradigm. We used a simple reaction time paradigm consisting of a vocal response (R1) and key-lift task (R2) with a stimulus onset asynchrony (SOA) between 100 ms and 1500 ms. On selected trials we implemented a startling acoustic stimulus concurrent with the second stimulus to determine if we could involuntarily trigger the second response. Our results indicated that the PRP delay in the second response was present for both control and startle trials at short SOAs, suggesting the second response was not prepared in advance. These results support a response preparation bottleneck and can be explained via a neural activation model of preparation. In addition, we found that the reflexive startle activation was reduced in the dual-task condition for all SOAs, a result we attribute to prepulse inhibition associated with dual-task processing.