Development of infant leg coordination: Exploiting passive torques

Leg joint coordination systematically changes over the first months of life, yet there is minimal data on the underlying change in muscle torques that might account for this change in coordination. The purpose of this study is to investigate the contribution of torque changes to early changes in leg joint coordination. Kicking actions were analyzed of 10 full-term infants between 6 and 15-weeks of age using three-dimensional kinematics and kinetics. We found 11 of 15 joint angle pairs demonstrated a change from more in-phase intralimb coordination at 6-weeks to less in-phase coordination at 15-weeks. Although the magnitude of joint torques normalized to the mass of the leg remained relatively consistent, we noted more complex patterns of torque component contribution across ages. By focusing on the change in torques associated with hip–knee joint coordination, we found that less in-phase hip–knee joint coordination at 15-weeks was associated with decreased influence of knee muscle torque and increased influence of knee gravitational and motion-dependent torques, supporting that infants coordinate hip muscle torque with passive knee gravitational and motion-dependent torques to generate kicks with reduced active knee muscle torque. We propose that between 6 and 15-weeks of age less in-phase hip–knee coordination emerges as infants exploit passive dynamics in the coordination of hip and knee motions.     

Re-examining the effects of verbal instructional type on early stage motor learning

The present study investigated the differential effects of analogy and explicit instructions on early stage motor learning and movement in a modified high jump task. Participants were randomly assigned to one of three experimental conditions: analogy, explicit light (reduced informational load), or traditional explicit (large informational load). During the two-day learning phase, participants learned a novel high jump technique based on the ‘scissors’ style using the instructions for their respective conditions. For the single-day testing phase, participants completed both a retention test and task-relevant pressure test, the latter of which featured a rising high-jump-bar pressure manipulation. Although analogy learners demonstrated slightly more efficient technique and reported fewer technical rules on average, the differences between the conditions were not statistically significant. There were, however, significant differences in joint variability with respect to instructional type, as variability was lowest for the analogy condition during both the learning and testing phases, and as a function of block, as joint variability decreased for all conditions during the learning phase. Findings suggest that reducing the informational volume of explicit instructions may mitigate the deleterious effects on performance previously associated with explicit learning in the literature.     

Task-specificity of balance training

Despite much research on balance training, it is still unclear whether balance training leads to highly task-specific adaptations or rather non-specific adaptations. Hence, in this study we examined whether balance training increased performance only in the balance task that was trained or also in non-trained tasks. Forty healthy participants (28 m 12 f, 25 ± 4 years, 177 ± 10 cm, 73 ± 14 kg) were assigned to one of two training groups (TGs) or a control group. Both TGs completed six sessions over 2 weeks, only the training device differed. Before and after the training, performance in the trained task as well as in additional untrained tasks was recorded. ANOVAs showed that each TG outperformed the other groups only in the task they had trained (e.g., task trained by TG1: +225% in TG1, only +41% and +30% in TG2 and control, group * time interaction, p < 0.001; Untrained task 1: TG1 +48%, TG2 +48%, and control +30%, no significant interaction, p = 0.72). In summary, 2 weeks of balance training resulted in highly task-specific effects, no transfer even to very similar tasks was observed. Therefore, we recommend identifying and training exactly those tasks that need improvement, and test the efficacy of training programs using specific tests instead of general tests with limited functional relevance.     

Age-associated differences in global and segmental control during dual-task walking under sub-optimal sensory conditions

The ability to safely perform cognitive-motor dual-tasks is critical for independence of older adults. We compared age-associated differences in global and segmental control during dual-task walking in sub-optimal sensory conditions. Thirteen young (YA) and 13 healthy older (OA) adults walked a straight pathway with cognitive dual-task of walking-while-talking (WT) or no-WT under four sensory conditions. On randomly selected trials, visual and vestibular inputs were manipulated using blurring goggles (BV) and Galvanic Vestibular Stimulation (GVS), respectively. Gait speed decreased more in YA than OA during WT. Gait speed increased with GVS with normal vision but not BV. Step length considerably decreased with WT. Trunk roll significantly decreased only in OA with GVS in WT. Head roll significantly decreased with GVS regardless of age. Results indicate GVS-induced adaptations were dependent on available visual information. YA reduced their gait speed more than OA to achieve a similar pace to safely perform WT. GVS resulted in both age-groups to reduce head movement. However, with the addition of WT during GVS, OA also stiffened their trunk. Therefore, with increased attentional demands healthy OA employed different compensatory strategies than YA to maintain postural control.     

Concurrent Movement Impairs Incidental But Not Intentional Statistical Learning

The effect of concurrent movement on incidental versus intentional statistical learning was examined in two experiments. In Experiment 1, participants learned the statistical regularities embedded within familiarization stimuli implicitly, whereas in Experiment 2 they were made aware of the embedded regularities and were instructed explicitly to learn these regularities. Experiment 1 demonstrated that while the control group were able to learn the statistical regularities, the resistance‐free cycling group and the exercise group did not demonstrate learning. This is in contrast with the findings of Experiment 2, where all three groups demonstrated significant levels of learning. The results suggest that the movement demands, rather than the physiological stress, interfered with statistical learning. We suggest movement activates the striatum, which is not only responsible for motor control but also plays a role in incidental learning.     

Boundary conditions for the influence of unfamiliar non-target primes in unconscious evaluative priming: The moderating role of attentional task sets

Evaluative priming by masked emotional stimuli that are not consciously perceived has been taken as evidence that affective stimulus evaluation can also occur unconsciously. However, as masked priming effects were small and frequently observed only for familiar primes that there also presented as visible targets in an evaluative decision task, priming was thought to reflect primarily response activation based on acquired S–R associations and not evaluative semantic stimulus analysis. The present study therefore assessed across three experiments boundary conditions for the emergence of masked evaluative priming effects with unfamiliar primes in an evaluative decision task and investigated the role of the frequency of target repetition on priming with pictorial and verbal stimuli. While familiar primes elicited robust priming effects in all conditions, priming effects by unfamiliar primes were reliably obtained for low repetition (pictures) or unrepeated targets (words), but not for targets repeated at a high frequency. This suggests that unfamiliar masked stimuli only elicit evaluative priming effects when the task set associated with the visible target involves evaluative semantic analysis and is not based on S–R triggered responding as for high repetition targets. The present results therefore converge with the growing body of evidence demonstrating attentional control influences on unconscious processing.     

External control of the stream of consciousness: Stimulus-based effects on involuntary thought sequences

The stream of consciousness often appears whimsical and free from external control. Recent advances, however, reveal that the stream is more susceptible to external influence than previously assumed. Thoughts can be triggered by external stimuli in a manner that is involuntary, systematic, and nontrivial. Based on these advances, our experimental manipulation systematically triggered a sequence of, not one, but two involuntary thoughts. Participants were instructed to (a) not subvocalize the name of visual objects and (b) not count the number of letters comprising object names. On a substantial proportion of trials, participants experienced both kinds of involuntary thoughts. Each thought arose from distinct, high-level processes (naming versus counting). This is the first demonstration of the induction of two involuntary thoughts into the stream of consciousness. Stimulus word length influenced dependent measures systematically. Our findings are relevant to many fields associated with the study of consciousness, including attention, imagery, and action control.     

Enhanced saccadic control in young people with Tourette syndrome despite slowed pro‐saccades

Tourette syndrome (TS) is a neurodevelopmental disorder characterized by motor and vocal tics. Tics are repetitive and uncontrolled behaviours that have been associated with basal ganglia dysfunction. We investigated saccadic eye movements in a group of young people with TS but without co‐morbid ADHD. Participants performed two tasks. One required them to perform only pro‐saccade responses (pure pro‐saccade task). The other involved shifting, unpredictably, between executing pro‐ and anti‐saccades (mixed saccade task). We show that in the mixing saccade task, the TS group makes significantly fewer errors than an age‐matched control group, while responding equally fast. By contrast, on the pure pro‐saccade task, the TS group were shown to be significantly slower to initiate and to complete the saccades (longer movement duration and decreased peak velocity) than controls, while movement amplitude and direction accuracy were not different. These findings demonstrate enhanced shifting ability despite slower reflexive responding in TS and are discussed with respect to a disorder‐related adaptation for increased cognitive regulation of behaviour.     

Two neglected moral emotions in university settings: some data on pride and shame

Pride and shame, two moral emotions partially neglected by the literature, can also be categorised as achievement emotions, because of their salience within everyday school and academic life. Our aims were to explore whether they are organised in a setting-specific manner and whether they differ in two settings, learning exam-relevant material and taking exams. Five hundred and forty university students evaluated pride and shame related to the two settings. A confirmatory multitrait-multimethod analysis (MTMM) indicated higher salience of type of emotion rather than type of setting; however, the structure of pride and shame was best explained when also type of setting was accounted for. A repeated-measure analysis of variance revealed higher levels of the positive emotion compared to the negative emotion, with the latter higher for the evaluative setting. Findings are discussed in light of their theoretical and applied relevance.     

Measuring drivers’ visual information needs during braking: A simulator study using a screen-occlusion method

It is commonly accepted that vision plays an important role in car braking, but it is unknown how people brake in the absence of visual information. In this simulator study, we measured drivers’ braking behaviour while they had to stop their car at designated positions on the road. The access to visual information was manipulated by occluding the screen at the start of half of the braking trials, while the temporal demand was manipulated by varying the time-to-arrival (TTA). Results showed that for the longer TTA values (⩾6 s), participants in the occlusion condition stopped too early and at variable positions on the road as compared to the control condition. In the occlusion condition, participants were likely to apply an intermediate brake pedal depression, whereas in the control condition participants more often applied low or high pedal depressions. The results are interpreted in light of a distance estimation test, in which we found that participants underestimated the actual distance by 70%.