Intra-individual variability in task performance after cognitive training is associated with long-term outcomes in children

The potential benefits and mechanistic effects of working memory training (WMT) in children are the subject of much research and debate. We show that after five weeks of school-based, adaptive WMT 6–9 year-old primary school children had greater activity in prefrontal and striatal brain regions, higher task accuracy, and reduced intra-individual variability in response times compared to controls. Using a sequential sampling decision model, we demonstrate that this reduction in intra-individual variability can be explained by changes to the evidence accumulation rates and thresholds. Critically, intra-individual variability is useful in quantifying the immediate impact of cognitive training interventions, being a better predictor of academic skills and well-being 6–12 months after the end of training than task accuracy. Taken together, our results suggest that attention control is the initial mechanism that leads to the long-run benefits from adaptive WMT. Selective and sustained attention abilities may serve as a scaffold for subsequent changes in higher cognitive processes, academic skills, and general well-being. Furthermore, these results highlight that the selection of outcome measures and the timing of the assessments play a crucial role in detecting training efficacy. Thus, evaluating intra-individual variability, during or directly after training could allow for the early tailoring of training interventions in terms of duration or content to maximise their impact.     

Effects of practice on variability, effects of variability on transfer

Five experiments examined how practice early in skill acquisition affected variability and accuracy during skill retention (Experiments 1-5) and skill transfer (Experiments 3, 4, 5). Lag constraints required that each path from apex to base of a computer-generated pyramid display differ from some number (the lag) of immediately prior paths. Location constraints specified end points at which paths must exit the pyramid. In all experiments, an early optimal period for acquiring a variability level was identified. Both low and high levels of variability were sustained during retention; high levels facilitated transfer. The results suggest that (a) early practice that requires high variability sensitizes learners to changes in condition and (b) such perception-performance links facilitate transfer by activating appropriate alternative strategies/schema or initiating their construction.     

Visual neglect in the first weeks after a stroke in the right hemisphere

The aim of the study was to characterize symptoms of visual neglect among patients who recently survived a stroke in the right hemisphere (RH), and to contribute to the understanding of change in symptoms during the first months after a RH stroke. Thirteen patients with a RH stroke and twenty controls were assessed by using standard neglect tests. Five patients were followed up by repetitive test sessions during the next four months. To assess more subtle symptoms, reaction-time (RT) measures derived from an experimental cue-target paradigm were included in the final test session. A high frequency of neglect symptoms was documented at the first test session. The changes in performance during the first weeks were characterized by a high inter-individual as well as a high intra-individual variability. Although the remission rate on standard tests was high in the follow-up study, the RT measures indicated sustained symptoms of visual extinction in all patients. The long-term implication of the changes of neglect symptoms during the first weeks after a stroke and signs of sustained symptoms of visual extinction calls for further longitudinal studies including a larger group of patients.     

Persistence and relapse of reinforced behavioral variability

The present study examined persistence and relapse of reinforced behavioral variability in pigeons. Pigeons emitted four‐response sequences across two keys. Sequences produced food according to a lag schedule, in which a response sequence was followed by food if it differed from a certain number of previous sequences. In Experiment 1, food was delivered for sequences that satisfied a lag schedule in both components of a multiple schedule. When reinforcement was removed for one component (i.e., extinction), levels of behavioral variability decreased for only that component. In Experiment 2, food was delivered for sequences satisfying a lag schedule in one component of a multiple schedule. In the other component, food was delivered at the same rate, but without the lag variability requirement (i.e., yoked). Following extinction, levels of behavioral variability returned to baseline for both components after response‐independent food delivery (i.e., reinstatement). In Experiment 3, one group of pigeons responded on a lag variability schedule, and the other group responded on a lag repetition schedule. For both groups, levels of behavioral variability increased when alternative reinforcement was suspended (i.e., resurgence). In each experiment, we observed some evidence for extinction‐induced response variability and for variability as an operant dimension of behavior.     

Exploring gait adaptations to perturbed and conventional treadmill training in Parkinson’s disease: Time-course,sustainability, and transfer

BackgroundGait impairment is a major motor symptom in Parkinson’s disease (PD), and treadmill training is an effective non-pharmacological treatment option.Research questionIn this study, the time course, sustainability and transferability of gait adaptations to treadmill training with and without additional postural perturbations were investigated.Methods38 PD patients (Hoehn & Yahr 1–3.5) were randomly allocated to eight weeks of treadmill training, performed twice-weekly for 40 min either with (perturbation treadmill training [PTT], n = 18) or without (conventional treadmill training [CTT], n = 20) additional perturbations to the treadmill surface. Spatiotemporal gait parameters were assessed during treadmill walking on a weekly basis (T0–T8), and after three months follow-up (T9). Additional overground gait analyses were performed at T0 and T8 to investigate transfer effects.ResultsTreadmill gait variability reduced linearly over the course of 8 weeks in both groups (p < .001; Cohen’s d (range): −0.53 to −0.84). Only the PTT group significantly improved in other gait parameters (stride length/time, stance-/swing time), with stride time showing a significant between-group interaction effect (Cohen’s d = 0.33; p = .05). Additional between-group interactions indicated more sustained improvements in stance (Cohen’s d = 0.85; p = .02) and swing time variability in the PTT group (Cohen’s d = 0.82; p = .03) at T9. Overground gait improvements at T8 existed only in stance (d = -0.73; p = .04) and swing time (d = 0.73; p = .04).DiscussionTreadmill stride-to-stride variability reduced substantially and linearly, but transfer to overground walking was limited. Adding postural perturbations tended to increase efficacy and sustainability of several gait parameters. However, since between-group effects were small, more work is necessary to support these findings.     

Attention failures versus misplaced diligence: separating attention lapses from speed-accuracy trade-offs

In two studies of a GO-NOGO task assessing sustained attention, we examined the effects of (1) altering speed-accuracy trade-offs through instructions (emphasizing both speed and accuracy or accuracy only) and (2) auditory alerts distributed throughout the task. Instructions emphasizing accuracy reduced errors and changed the distribution of GO trial RTs. Additionally, correlations between errors and increasing RTs produced a U-function; excessively fast and slow RTs accounted for much of the variance of errors. Contrary to previous reports, alerts increased errors and RT variability. The results suggest that (1) standard instructions for sustained attention tasks, emphasizing speed and accuracy equally, produce errors arising from attempts to conform to the misleading requirement for speed, which become conflated with attention-lapse produced errors and (2) auditory alerts have complex, and sometimes deleterious, effects on attention. We argue that instructions emphasizing accuracy provide a more precise assessment of attention lapses in sustained attention tasks.     

Relationship between sustained,orientated, divided,and selective attention and simulated aviation performance: Training & pressure effects

The present study examined how different characteristics of visual attention are related to flying ability. Eighty participants completed one of four attentional tests designed to assess sustained attention (SUSTAIN), attentional orienting (ORIENT), divided attention (DIVIDE) or selective attention (SELECT). Median splits were used to create low and high groups. After completing training, participants executed simulated landings under conditions of high anxiety. For the DIVIDE test, there were significant group differences in: (i) landing ability after training and (ii) the effects of anxiety. The high DIVIDE group had lower root mean square (RMS) errors at the end of training and were less affected by anxiety as compared to the low DIVIDE group. For the ORIENT and SELECT tests, there were significant group effects for training but not for anxiety. The high groups for these tests displayed lower RMS errors following training. There were no group differences for the SUSTAIN test. The results suggest that a test of divided attention may be useful for operational assessment of pilots.     

Effects of Practice Variability on Unimanual Arm Rotation

High variability practice has been found to lead to a higher rate of motor learning than low variability practice in sports tasks. The authors compared the effects of low and high levels of practice variability on a simple unimanual arm rotation task. Participants performed rhythmic unimanual internal-external arm rotation as smoothly as possible before and after 2 weeks of low (LV) or high (HV) variability practice and after a 2-week retention interval. Compared to the pretest, the HV group significantly decreased hand, radioulnar, and shoulder rotation jerk on the retention test and shoulder jerk on the posttest. After training the LV group had lower radioulnar and shoulder jerk on the posttest but not the retention test. The results supported the hypothesis that high variability practice would lead to greater learning and reminiscence than low variability practice and the theoretical prediction of a bifurcation in the motor learning dynamics.     

Brief report: Cool down: A procedure for decreasing aggression in adults with traumatic head injury

The application of techniques for reducing verbal and physical aggression can be problematic when the procedures are applied to high functioning adults who have sustained a traumatic head injury. In this investigation, the effect of a ‘cool down’ training procedure on two adult males with brain injuries was examined using the same strategy, which was simultaneously applied to both behaviors for 1 subject and applied only to verbal aggression for a second subject. The cool down training procedure included 2 training sessions per week, plus implementation of a modified training program in the test situation. Results revealed that the cool down training program was effective in reducing both verbal and physical aggression and therefore provides an alternative treatment for adults with head injuries.     

Operant conditioning of behavioral variability using a percentile reinforcement schedule.

The present investigation developed and tested a new percentile reinforcement schedule suited to study pattern variability, whose main feature was the relative dissociation it provided between the variability requirement defining criterional responses and overall probability of reinforcement. In a discrete-trials procedure, pigeons produced patterns of four pecks on two response keys. If the pattern emitted on the current trial differed from the N preceding patterns, reinforcement was delivered with probability mu. The schedule continuously adjusted the criterion N such that the probability of a criterional response, estimated from the subject's recent behavior, was always constant. In these circumstances, the criterion corresponded to an invariant percentile in the distribution of recent responses. Using a between-subjects design, Experiment 1 manipulated the variability requirement--the percentile--while keeping overall reinforcement probability constant. The degree of variability varied directly with the requirement. In addition, an inverse relationship existed between the requirement and within-group variance. Experiment 2 manipulated probability of reinforcement while maintaining the variability requirement constant. No consistent relationship was found between variability and reinforcement probability. A tentative hypothesis was advanced ascribing the operant conditioning of behavioral variability to a process of probability-dependent selection.     

The impact of a new emotional self-management program on stress, emotions, heart rate variability, DHEA and cortisol

This study examined the effects on healthy adults of a new emotional self-management program, consisting of two key techniques, “Cut-Thru” and the “Heart Lock-In.” These techniques are designed to eliminate negative thought loops and promote sustained positive emotional states. The hypotheses were that training and practice in these techniques would yield lowered levels of stress and negative emotion and cortisol, while resulting in increased positive emotion and DHEA levels over a one-month period. In addition, we hypothesized that increased coherence in heart rate variability patterns would be observed during the practice of the techniques. Forty-five healthy adults participated in the study, fifteen of whom acted as a comparison group for the psychological measures. Salivary DHEA/DHEAS and cortisol levels were measured, autonomic nervous system function was assessed by heart rate variability analysis, and emotions were measured using a psychological questionnaire. Individuals in the experimental group were assessed before and four weeks after receiving training in the self-management techniques. The experimental group experienced significant increases in the positive affect scales of Caring and Vigor and significant decreases in the negative affect scales of Guilt, Hostility, Burnout, Anxiety and Stress Effects, while no significant changes were seen in the comparison group. There was a mean 23 percent reduction in cortisol and a 100 percent increase in DHEA/DHEAS in the experimental group. DHEA was significantly and positively related to the affective state Warmheartedness, whereas cortisol was significantly and positively related to Stress Effects. Increased coherence in heart rate variability patterns was measured in 80 percent of the experimental group during the use of the techniques. The results suggest that techniques designed to eliminate negative thought loops can have important positive effects on stress, emotions and key physiological systems. The implications are that relatively inexpensive interventions may dramatically and positively impact individuals’ health and well-being. Thus, individuals may have greater control over their minds, bodies and health than previously suspected.     

The effect of external perturbations on variability in joint coupling and single joint variability

This paper explores the effect of goal-oriented external perturbations created by elastic tubes attached to the hip and ankles on lower limb joint variability and hip–knee and knee–ankle coordination variability during running. Kinematics of ten healthy male runners were analysed prior to and following a 7-week tube running intervention while running with and one without this constraint. The training intervention was based on variable training aspects to increase within-movement variability and adaptability of the running pattern. To analyse the effects of the tubes on the running pattern, the phase plot vector length deviation (i.e., the standard deviation of the phase plot vector length) for the within-joint variability and the continuous relative phase variability for the joint coupling variability were calculated. Results revealed acute increases of variability in both parameters. However, after the intervention, variability of the tube running situation returned to normal for all couplings and joints except the knee. No transfer effects to normal running were observed. This suggests very rapid adaptations to such perturbations. In the long-term, it may ask for more or different variations.     

Behavioral predictors of blood pressure variation in hypertensives and normotensives

This study examined the relative impact of five behavioral factors--activity, posture, location, social involvement, and tension--on the 24-hr blood pressure (BP) variability of 21 normotensives, 18 borderline hypertensives, and 18 sustained essential hypertensives. Multiple-regression analyses indicated that within each diagnostic group, activity accounted for more variance in BP variability than any other behavioral dimension. For each behavioral dimension examined, the magnitude of the relationship with BP was generally greater for the normotensives than for both hypertensive groups. In contrast, variation due to individuals was a better predictor of BP variability for the two hypertensive groups than for the normotensive group. Number of months hypertensive and use of antihypertensive medication were related to BP variability for the sustained hypertensive group. Findings have implications for the use of ambulatory BP monitors and interpretation of resulting data.     

Mentoring for Responsible Research: The Creation of a Curriculum for Faculty to Teach RCR in the Research Environment

Despite more than 25 years of a requirement for training in the responsible conduct of research (RCR), there is still little consensus about what such training should include, how it should be delivered, nor what constitutes “effectiveness” of such training. This lack of consensus on content, approaches and outcomes is evident in recent data showing high variability in the development and implementation of RCR instruction across universities and programs. If we accept that one of the primary aims of instruction in RCR/research ethics is “to foster a community of social responsibility” (Antes et al. 2009: 398), then it makes sense to consider the research environment itself—where learning one’s science happens where one also engages in social interaction around that science. In order to take the best advantage of that already existing/naturally occurring research environment, the authors, through a deliberative, collaborative, and integrative process, crafted a workshop curriculum meant to arm research faculty with concrete and specific tools to effectively introduce research ethics in the context of the research environment.     

Comparative analyses of rider position according to skill levels during walk and trot in Jeju horse

The purpose of this study was to evaluate the rider position at walk and trot as a function of rider skill level by analyzing joint angles. Participants included three advanced riders and six beginners, and training was conducted for one hour, twice a week for 24 weeks. In the walk stage of the beginners’ group, the elbows and shoulders sustained postures comparable to those of the advanced riders group; the trunk tilted forwards at first, but later it tilted slightly behind the vertical. The knee, ankle, and left–right angle kept stable postures after 12 weeks of training (p < .05). The front-rear (FR) angle of the beginners group improved during training, but it was still lower than the advanced riders group after 24 weeks of training (p < .05). At trot, while the knee angle measurement of the beginners’ group was similar to the advanced riders, the ankle joint sustained a forward point posture. The ankle joint maintained dorsiflexion posture with 83.9° ± 5.3 in the advanced riders group, while the beginners group had plantar flexion posture with 98.7° ± 6.0. This study suggested that the correlation between the joint and body segment angles could be an important indicator in the evaluation of rider proficiency.     

Stress management and exercise training in chronic stable angina pectoris

Abstract

Patients suffering from chronic stable angina pectoris were allocated to one of four conditions: stress management training, exercise training, combined stress management and exercise, or waiting list control. Patients undertook an exercise tolerance test before and after intervention, and at follow-up assessment eight weeks later. They also kept a daily diary of the frequency, duration and intensity of all angina episodes, and recorded the amount of medication taken, for the week preceding and the week following intervention, as well as for the eighth week of follow-up. Patients who undertook the combined stress management and exercise programme faired best. They showed sustained gains in achieved workload on the exercise tolerance test at no cost in terms of ischaemia, as measured by ST-segment depression. They also registered less frequent angina attacks following intervention than the exercise only and waiting list control patients, and reported reduced reliance on medication; the latter benefit was sustained at follow-up. These clinical dividends invite further study of combined stress management and exercise training in angina pectoris.     

Self-reinforcement in pigeons

Pigeons were trained to reward their own performances by eating from a freely available food source only after pecking a disc. The self-reinforcement pattern was established by fading in the work requirement and punishing noncontingent self-feeding by food withdrawal. The animals maintained faultless self-reinforcement for hundreds of trials after the punishment contingency was removed so that the birds could safely feed themselves without performing any pecking responses. In successive induction and extinction of the phenomenon, the number of responses per self-reward was observed to covary with self-reinforcement rate. By progressively raising the work requirements an animal was trained to adopt increasingly higher performance standards of self-reward. After maintaining a high response output for each self-reward the animal promptly discarded all self-imposed work contingencies and quickly resumed them again, though less durably, following additional training.     

Does word training increase or decrease interference in a stroop task?

First and second graders (6- and 7-year-olds) practiced reading 20 words. Before and after word training, they named pictures printed with and without these words as distractors. Of interest was whether training would enhance or diminish the interference created by these words in the picture-naming task. Results indicated that children who learned to recognize unfamiliar distractor words more accurately suffered more interference after training. In contrast, children who were already familiar with the words and learned to recognize them faster experienced less interference following training. Results are interpreted as supporting LaBerge and Samuels' model of automatic word processing. Effects of accuracy training are attributed to the elimination of attention as a requirement for processing distractor words. Effects of speed training are attributed to a reduction in the time consumed by distractor words in the central processor.     

Further Tests of Schmidt’s Schema Theory

The present study investigated the generalizability of Schmidt’s (1975) schema theory to an open-skill (Poulton, 1957) situation. Subjects attempted to time a preferred-hand button press so that it was coincident with the lighting of the last of a series of runway lights whose apparent velocity was 4023 mm/sec. Prior to five trials of performance on the criterion task, subjects received 40 trials in which they either (a) watched (low response requirements) or (b) responded with the nonpreferred hand (high response requirements) to a stimulus moving at (a) a constant (2235, 3129, 4917, or 5812 mm/sec) velocity (low stimulus variability) or (b) different velocities (high stimulus variability) from trial to trial. Subjects receiving high stimulus variability and high response requirements during training had significantly lower absolute error on the criterion task than did those in the other conditions. The results were discussed in terms of the type of practice which facilitates development of a schema rule for coincident-timing situations.     

The Development of Sustained Attention in Children: The Effect of Age and Task Load

This study explored how children's sustained attention develops and the effect of manipulating task parameters on sustained attention. The sample comprised 57 children (5–12 years) who completed CogState and Score! (Test of Everyday Attention for Children). Novel variability and traditional indices indicated rapid development from 5–6 to 8–9 years on all measures and a developmental plateau from 8–9 to 11–12, with growth evident on some measures. Findings suggest that sustained attention improves to age 10, then plateaus with only minor improvements. Further, performance was generally poorer on high load tasks compared to low load, with the same developmental pattern uncovered.