Grip Force-Load Force Coupling Is Influenced by Altered Visual Feedback about Object Kinematics

Abstract

Recent evidence suggests that visual feedback influences the adjustment of grip force to the changing load force exerted by a grasped object as it is manipulated. The current project investigated how visual feedback of object kinematics affects the coupling of grip force to load force by scaling the apparent displacements of the object viewed in virtual reality. Participants moved the object to manually track a moving virtual target. The predictability of the changing load force exerted by the object was also manipulated by altering the nature of target trajectories (and therefore the nature of object motions). When apparent object displacements increased in magnitude, grip force became more tightly coupled to load force over time. Furthermore, when load force variations were less predictable, the magnitude of apparent object displacements affected the relative degree of continuous versus intermittent coupling of grip force to load force. These findings show that visual feedback of object motion affects the ongoing dynamical coupling between grip force control and load force experienced during manipulation of a grasped object.     

Grip Control in Children before,during, and after Impulsive Loading

The manipulation of small objects requires continuous contributions from both predictive and reactive mechanisms. The authors aimed to study the development of predictive and reactive mechanisms used by children from 6 to 14 years of age to manage impulsive loading. The load of a handheld object was increased rapidly by the drop of a weight hung on the object. The drop was triggered either by the child (predictive condition) or by the examiner (reactive condition). Regardless of the condition, the control strategy was refined with age. Younger children were unable to adapt their grip force (GF) to the friction of their fingers, whereas the older children provided GF that was well adapted to their variable coefficient of friction, thereby producing a secure grip. This reflected either an inadequate amount of force or an inability to integrate cutaneous information from the fingers in younger children. Additionally, a modulation with age for both predictive and reactive mechanisms was observed. All together, the better predictive abilities and the more secure grip exhibited by older children allow decreased slipping and improved performance in an impulsive loading task.     

The effects of stressor predictability on lymphocyte proliferation in humans

Abstract

To demonstrate the effects of predictable and unpredictable stressors on immune function, 36 male subjects were randomly assigned to complete ten trials of either a predictable or unpredictable cold pressor task or a non-stressful warm pressor control task. The predictable and no-stressor groups were given information about the duration of each pressor trial and a countdown of seconds passed from beginning to end of each trial. The unpredictable stressor group received no information. Self-report, cardiovascular, and biochemical measures were taken throughout the tasks in order to ascertain the effectiveness of the predictability and stressor manipulations. Lymphocyte proliferation to concanavalin A (Con A) and pokeweed mitogen (PWM) were measured before, during and after the tasks. Lymphocyte proliferation to Con A (10/μg/ml) was significantly reduced only in response to the unpredictable stressor suggesting that predictability buffered the effect of the stressor on immune function. Proliferation to PWM followed a similar pattern but was not statistically significant. Blood pressure responses were negatively correlated with proliferation values suggesting that stressor predictability may attenuate stress-associated immune decreases by reducing sympathetic arousal.     

Panic-relevant predictability preferences: a laboratory test

In the present investigation the authors evaluated the role of verbally instructed safety periods as they relate to predictability preference within a single-session challenge paradigm involving recurrent administrations of 20% carbon dioxide (CO-sub-2) enriched air. Participants included 160 nonclinical young adults (91 women, 69 men) between the ages of 18 and 59 (M=21.6 years; SD=7.23). Results indicated that equivalent levels of anxiety were experienced during predictable and unpredictable administrations of 20% CO-sub-2, yet participants preferred predictable compared with unpredictable trials, with women showing a stronger predictability preference than men. Lower anxiety was reported during known safety periods (predictable room air trials) but not during predictable compared with unpredictable administrations of 20% CO-sub-2. Findings are discussed in relation to theoretical and applied implications for the role of predictability in the nature of anxiety and its disorders.     

The Effects of Brain Lateralization on Motor Control and Adaptation

ABSTRACT

Lateralization of mechanisms mediating functions such as language and perception is widely accepted as a fundamental feature of neural organization. Recent research has revealed that a similar organization exists for the control of motor actions, in that each brain hemisphere contributes unique control mechanisms to the movements of each arm. The authors review present research that addresses the nature of the control mechanisms that are lateralized to each hemisphere and how they impact motor adaptation and learning. In general, the studies suggest an enhanced role for the left hemisphere during adaptation, and the learning of new sequences and skills. The authors suggest that this specialization emerges from a left hemisphere specialization for predictive control—the ability to effectively plan and coordinate motor actions, possibly by optimizing certain cost functions. In contrast, right hemisphere circuits appear to be important for updating ongoing actions and stopping at a goal position, through modulation of sensorimotor stabilization mechanisms such as reflexes. The authors also propose that each brain hemisphere contributes its mechanism to the control of both arms. They also discuss the potential advantages of such a lateralized control system.     

Grip and load force control and coordination in individuals with diabetes in different manipulation tasks

The study aimed to investigate the control and coordination of grip force (normal component) and load force (tangential component) in three different manipulation tasks in individuals with diabetes with and with no diagnosis of diabetic peripheral neuropathy (DPN) and healthy controls. Twenty-four individuals with type 2 diabetes mellitus, 12 with no (nDPN) and 12 with DPN (wDPN), and 12 healthy controls performed three manipulation tasks (static holding, lifting and holding, and oscillation) with the dominant hand, using an instrumented handle. Relative safety margin (% of GF exerted above the minimum GF needed to hold the object) was measured in all tasks. Individuals with diabetes from the nDPN and wDPN groups set lower relative safety margin than controls only in the static holding task. No other group effect was revealed, except a lower coefficient of friction between skin and object surface in individuals with DPN. The coordination between grip and load force and grip force control was not affected by the diabetes during dynamic manipulation tasks (lifting and holding and oscillation). However, when individuals with diabetes without and with DPN performed a manipulation task in which the inflow of cutaneous information was small and stable (static holding), grip force control was affected by the disease. This finding indicates that individuals with type 2 diabetes mellitus not diagnosed with DPN, already show mild impairments in the nervous system that could affect grip force control and that could be one of the first signs of neuropathy caused by the diabetes.     

Auditory feedback control in adults who stutter during metronome-paced speech I. Timing Perturbation

PurposeThis study determined whether adults who stutter (AWS) exhibit deficits in responding to an auditory feedback timing perturbation, and whether external timing cues, which increase fluency, attenuate any disruptions due to altered temporal auditory feedback.MethodsFifteen AWS and sixteen adults who do not stutter (ANS) read aloud a multisyllabic sentence either with normal pacing or with each syllable paced at the rate of a metronome. On random trials, an auditory feedback timing perturbation was applied, and timing responses were compared between groups and pacing conditions.ResultsBoth groups responded to the timing perturbation by delaying subsequent syllable boundaries, and there were no significant differences between groups in either pacing condition. Furthermore, no response differences were found between normally paced and metronome-paced conditions.ConclusionThese findings are interpreted as showing that 1) AWS respond normally to pure timing perturbations, and 2) metronome-paced speech has no effect on online speech timing control as assessed in the present experiment.     

Effects of Visual Error Timing on Smooth Pursuit Gain Adaptation in Humans

Smooth pursuit (SP) is one of the precise oculomotor behaviors when tracking a moving object. Adaptation of SP is based on a visual-error driven motor learning process associated with predictable changes in the visual environment. Proper timing of a sensory signal is an important factor for adaptation of fine motor control. In this study, we investigated whether visual error timing affects SP gain adaptation. An adaptive change in SP gain is produced experimentally by repeated trials of a step-ramp tracking with 2 different velocities (double-velocity paradigm). The authors used the double-velocity paradigm where target speed changes 400 or 800 ms after the target onset. The results show that SP gain changed in a certain time window following adaptation. The authors suggest that SP adaptation shown in this study is associated with timing control mechanisms.     

The Effects of Practice and External Support on Older Adults' Control of Reflexive Eye Movements

ABSTRACT

The present study examined whether external support and practice could reduce age differences in oculomotor control. Participants were to avoid fixating an abrupt onset and on some trials, were provided with a predictive cue regarding the onset location or identity. Older adults demonstrated more capture than younger adults, but both groups improved with practice. Whereas the older group benefited from a location preview (Experiment 1), neither group showed less capture when given a preview of the onset object itself (Experiment 2), suggesting that location-based inhibition, but not object-based inhibition, was sufficient to support oculomotor control within this paradigm. To test the generalizability of these skills, displays in a final block were manipulated such that the onset could appear in a different location or be a different object altogether. Viewing patterns were similar for changed vs. unchanged displays, suggesting that participants' practice-related gains could withstand a change in the task materials.     

The effects of age and set size on the fast extraction of egocentric distance

ABSTRACT

Angular direction is a source of information about the distance to floor-level objects that can be extracted from brief glimpses (near one's threshold for detection). Age and set size are two factors known to impact the viewing time needed to directionally localize an object, and these were posited to similarly govern the extraction of distance. The question here was whether viewing durations sufficient to support object detection (controlled for age and set size) would also be sufficient to support well-constrained judgments of distance. Regardless of viewing duration, distance judgments were more accurate (less biased towards underestimation) when multiple potential targets were presented, suggesting that the relative angular declinations between the objects are an additional source of useful information. Distance judgments were more precise with additional viewing time, but the benefit did not depend on set size and accuracy did not improve with longer viewing durations. The overall pattern suggests that distance can be efficiently derived from direction for floor-level objects. Controlling for age-related differences in the viewing time needed to support detection was sufficient to support distal localization but only when brief and longer glimpse trials were interspersed. Information extracted from longer glimpse trials presumably supported performance on subsequent trials when viewing time was more limited. This outcome suggests a particularly important role for prior visual experience in distance judgments for older observers.     

Cognitive control of action naming in adults who stutter

PurposeBased on previous evidence that cognitive control of lexical selection in object (noun) naming operates differently in adults who stutter (AWS) versus typically-fluent adults (TFA), the aim was to investigate cognitive control of lexical selection in action (verb) naming in AWS.Method12 AWS and 12 TFA named line drawings depicting actions using verbs. Half of the pictures had high-agreement action names and the other half low-agreement action names. Naming accuracy and reaction times (RT), and event-related potentials (ERPs) time-locked to picture onset, were compared between groups.ResultsNaming RTs were slower for low- versus high-agreement trials, and the magnitude of this effect was larger in AWS versus TFA. Delta-plot analysis of naming RTs revealed that individual differences in selective inhibition were associated with the agreement effect on naming RTs in AWS but not TFA. Action naming elicited frontal-central N2 activity in both agreement conditions in TFA but not AWS. Additionally, a later, posterior P3b component was affected by agreement in TFA only. In AWS, low-agreement action naming elicited frontal P3a activation.ConclusionsResults suggest that cognitive control of action name selection was qualitatively different between groups. In TFA, cognitive control of lexical selection in action naming involved nonselective inhibition, as well as more efficient working memory updating on high- versus low-agreement trials. In AWS, cognitive control of low-agreement action naming involved increased focal attention. Individual differences in selective inhibition may have moderated cognitive control of action naming in AWS.     

Validation of the French version of the Object Spatial Imagery and Verbal Questionnaire

IntroductionThe Object Spatial Imagery and Verbal Questionnaire (OSIVQ) measures individual differences in Visual-Verbal cognitive style and distinguishes between spatial and object visual imagery.ObjectiveThe aim of this study was to evaluate the psychometric properties of a French version of the OSIVQ.MethodSeven hundred fifty-two participants completed the French OSIVQ and 144 of them also completed a paper-and-pencil assessment to evaluate spatial imagery, object imagery and verbal abilities.ResultsPrincipal component analyses of the OSIVQ showed good internal construct validity. Results also revealed pronounced individual differences and a significant gender effect. Confirmatory factorial analyses gave support to a three-dimensional model of cognitive style. Furthermore, correlations were observed across the different dimensions of the questionnaire and specific paper-and-pencil tasks.ConclusionOur results highlight the good psychometric properties of the French version of the OSIVQ.     

The Disambiguation Prediction Effect

ABSTRACT

Children tend to select a novel object rather than a familiar object when asked to identify the referent of a novel label. Current accounts of this so-called disambiguation effect do not address whether children have a general metacognitive representation of this way of determining the reference of novel labels. In two experiments (each N = 48), three- and four-year-olds received a prediction task that required such a representation. In the initial phase, children completed four disambiguation test trials that were presented as instances of the same “game.” In the next phase, they received four additional trials. These differed only in that before the label was presented, children were asked to predict which object “was going to be right.” On the first prediction trial, most four-year-olds predicted the novel object, whereas most three-year-olds did not. On subsequent trials, despite having received feedback regarding predictions, three-year-olds showed no tendency to begin to predict the novel object, whereas most four-year-olds continued to make this prediction. These findings add to the evidence that most children develop a general metacognitive representation of their tendency to map novel labels onto novel rather than familiar objects some time around their fourth birthday.     

The Value of Zoo Experiences for Connecting People with Nature

ABSTRACT

Zoos aspire to bring people closer to nature through visitor education and by creating environments that immerse visitors into naturalistic surroundings. Yet to date, the psychological and behavioral consequences of these attempts have not been well-documented through empirical study. The present study was designed to determine if visiting a zoo had a measurable impact on visitors' relationships with nature and to test whether this effect was moderated by the zoo setting and/or type of zoo experience. Data were collected from three different types of zoos in New York City. A total of 242 zoo visitors participated in this study by completing a set of scales measuring explicit and implicit self-nature associations. Findings suggest that zoo experiences do promote an increased implicit connectedness with nature, but no changes were found for self-reported explicit connectedness with nature. The authors found no evidence that this effect was moderated by a specific design strategy or scale of institution.     

Relationships between stigma-identity constructs and psychological health outcomes among adults who stutter

PurposeIn the current study, stuttering was conceptualized as a concealable stigmatized identity (CSI). The purpose of this investigation was to determine if four specific stigma-identity constructs that contribute to variability in psychological distress among people in other CSI groups also contribute among adult who stutter (AWS).Method505 AWS completed an online survey that included measures of four stigma-identity constructs in addition to general demographics and measures of self-rated stuttering severity, distress, and adverse impact of stuttering on quality of life. Hierarchical regression was performed to determine the extent that stigma-identity constructs explained variability in psychological health outcomes among AWS. Self-rated stuttering severity was investigated as a moderator in these relationships.ResultsThe stigma-identity constructs accounted for a significant proportion of the variability in distress (∼25 %) and adverse impact of stuttering on quality of life (∼30 %) among AWS. Further, the constructs of salience, centrality, and concealment were positively predictive of distress and adverse impact of stuttering after controlling for demographics and neuroticism. Compared to the other predictor variables (self-rated stuttering severity, demographic characteristics, neuroticism, and the three other stigma-identity constructs), concealment was the strongest predictor of adverse impact of stuttering on quality of life. Finally, self-rated stuttering severity was a moderating variable.ConclusionsThe results from this study suggest that there are useful applications in conceptualizing stuttering as a type of CSI. Speech-language pathologists should be aware of the relationships that stigma has with psychological health outcomes among AWS and should consider the implications for intervention.     

The strings on David’s Harp: religious ritual as a container for spirituality

ABSTRACT

Religion and spirituality have often been defined over against each other. The spontaneous, emotional and experiential nature of the spirit has been seen as preferential to the structured, fixed, and predictable nature of religious ritual. Religion education for children has moved away from the performance of ritual behaviour toward creating an environment to nurture the innate spiritual nature of children. This paper questions whether the pendulum has swung too far, neglecting rituals that have sustained religious and communal life for generations, and considers ways of reimagining traditional ritual as a way to encounter the spirit and build community.     

Psychological Predictors of Coping Responses Among Greek Basketball Referees

Abstract

The authors examined the effects of situational appraisals (perceived control and intensity), coping styles (monitoring and blunting), and personal dispositions (optimism and self-esteem) on the approach and avoidance coping responses of skilled Greek basketball referees (N = 162) and the consistency of their responses following 3 game-related stressful situations. In an effort to clarify the variables involved in coping and to consider the theoretical principles both within and beyond sports, the authors replicated an earlier study among Australian basketball referees (A. Kaissidis-Rodafinos, M. H. Anshel, & A. Porter, 1997). The results were equivocal: The Greek referees were not consistent in using avoidance and approach coping responses across situations. Approach coping was more predictable than avoidance coping in accounting for both situational and personal variables.     

On the role of lyrics in the music–exercise performance relationship

ObjectivesTo examine the role of lyrics on a range of psychological, psychophysical, and physiological variables during submaximal cycling ergometry.DesignWithin-subject counterbalanced design.MethodTwenty-five participants performed three 6-min cycling trials at a power output corresponding to 75% of their maximum heart rate under conditions of music with lyrics, same music without lyrics, and a no-music control. Cycling cadence, heart rate, and perceived exertion were recorded at 2-min intervals during each trial. Positive and negative affect was assessed before and after each trial.ResultsParticipants cycled at a higher cadence towards the end of the cycling trials under music with lyrics. Main effects were found for perceived exertion and heart rate, both of which increased from min 2 through to min 6, and for affect: positive affect increased and negative affect decreased from pre- to post-trials.ConclusionsParticipants pedalled faster in both music conditions (with and without lyrics) while perceived exertion and heart rate did not differ. The inclusion of lyrics influenced cycling cadence only at min 6 and had no effect on the remaining dependent variables throughout the duration of the cycling trials. The impact of lyrical content in the music–exercise performance relationship warrants further attention in order for us to better understand its role.     

Goal saliency boosts infants’ action prediction for human manual actions,but not for mechanical claws

Previous research indicates that infants’ prediction of the goals of observed actions is influenced by own experience with the type of agent performing the action (i.e., human hand vs. non-human agent) as well as by action-relevant features of goal objects (e.g., object size). The present study investigated the combined effects of these factors on 12-month-olds’ action prediction. Infants’ (N = 49) goal-directed gaze shifts were recorded as they observed 14 trials in which either a human hand or a mechanical claw reached for a small goal area (low-saliency goal) or a large goal area (high-saliency goal). Only infants who had observed the human hand reaching for a high-saliency goal fixated the goal object ahead of time, and they rapidly learned to predict the action goal across trials. By contrast, infants in all other conditions did not track the observed action in a predictive manner, and their gaze shifts to the action goal did not change systematically across trials. Thus, high-saliency goals seem to boost infants’ predictive gaze shifts during the observation of human manual actions, but not of actions performed by a mechanical device. This supports the assumption that infants’ action predictions are based on interactive effects of action-relevant object features (e.g., size) and own action experience.     

Neurocognitive Contributions to Motor Skill Learning: The Role of Working Memory

ABSTRACT

Researchers have begun to delineate the precise nature and neural correlates of the cognitive processes that contribute to motor skill learning. The authors review recent work from their laboratory designed to further understand the neurocognitive mechanisms of skill acquisition. The authors have demonstrated an important role for spatial working memory in 2 different types of motor skill learning, sensorimotor adaptation and motor sequence learning. They have shown that individual differences in spatial working memory capacity predict the rate of motor learning for sensorimotor adaptation and motor sequence learning, and have also reported neural overlap between a spatial working memory task and the early, but not late, stages of adaptation, particularly in the right dorsolateral prefrontal cortex and bilateral inferior parietal lobules. The authors propose that spatial working memory is relied on for processing motor error information to update motor control for subsequent actions. Further, they suggest that working memory is relied on during learning new action sequences for chunking individual action elements together.