Dave A Gonzalez

Handedness throughout the lifespan: cross-sectional view on sex differences as asymmetries change

Manual asymmetries has been studied by many researchers, however contradictory findings still exist as to whether preferred manual asymmetries increases with age or do we become more ambidextrous. Recently it was shown that perhaps there is a third option, that there is no increase or decrease in laterality but rather preferred manual asymmetries remains consistent throughout adulthood. Another related finding is that females appear to have an advantage in some handedness tasks, such as the Grooved Pegboard. When a larger pegboard is used, sex differences may reverse as males may perform better when larger pegs and a larger trajectory are required. However, it is not fully understood if these sex differences arise from an early age and continue throughout life. Therefore, we sought to explore sex differences in preferred hand dominance throughout the lifespan. In order to explore preferred hand dominance during the lifespan we examined 76 children (19.4–5 year olds, 12 female, Mage = 4.73; 34.6–8 year olds, 12 female, Mage = 6.97; 23.9–12 year olds, 14 female, Mage = 10.83) in Experiment 1 and 35 healthy young right-handed adults (15 female, Mage = 20.91) and 37 healthy older right-handed adults (20 female, Mage = 72.3) in Experiment 2. Individuals were tested using a standard size (small) and modified Grooved Pegboard (larger pegboard). Our study demonstrates that hand asymmetries are present early in life (children 4–5 years old) at that these differences attenuate as a function of age until adulthood (Experiment 1). Furthermore, our results demonstrate that as we age (Experiment 2), asymmetries may increase (small and large pegboards), decrease (Annett), or stay the same (finger tapping). As well we demonstrated that the sex differences could not be entirely accounted for by hand size. Therefore, asymmetries as regard to the aging process, seems to be task specific which may account for the conflicting findings in research.

Executive function deficits in team sport athletes with a history of concussion revealed by a visual-auditory dual task paradigm

ABSTRACT The purpose of this study was to examine executive functions in team sport athletes with and without a history of concussion. Executive functions comprise many cognitive processes including, working memory, attention and multi-tasking. Past research has shown that concussions cause difficulties in vestibular-visual and vestibular-auditory dual-tasking, however, visual-auditory tasks have been examined rarely. Twenty-nine intercollegiate varsity ice hockey athletes (age = 19.13, SD = 1.56; 15 females) performed an experimental dual-task paradigm that required simultaneously processing visual and auditory information. A brief interview, event description and self-report questionnaires were used to assign participants to each group (concussion, no-concussion). Eighteen athletes had a history of concussion and 11 had no concussion history. The two tests involved visuospatial working memory (i.e., Corsi block test) and auditory tone discrimination. Participants completed both tasks individually, then simultaneously. Two outcome variables were measured, Corsi block memory span and auditory tone discrimination accuracy. No differences were shown when each task was performed alone; however, athletes with a history of concussion had a significantly worse performance on the tone discrimination task in the dual-task condition. In conclusion, long-term deficits in executive functions were associated with a prior history of concussion when cognitive resources were stressed. Evaluations of executive functions and divided attention appear to be helpful in discriminating participants with and without a history concussion.

Binocular advantage for prehension movements performed in visually enriched environments requiring visual search.

The purpose of this study was to examine the role of binocular vision during a prehension task performed in a visually enriched environment where the target object was surrounded by distractors/obstacles. Fifteen adults reached and grasped for a cylindrical peg while eye movements and upper limb kinematics were recorded. The complexity of the visual environment was manipulated by varying the number of distractors and by varying the saliency of the target. Gaze behavior (i.e., the latency of the primary gaze shift and frequency of gaze shifts prior to reach initiation) was comparable between viewing conditions. In contrast, a binocular advantage was evident in performance accuracy. Specifically, participants picked up the wrong object twice as often during monocular viewing when the complexity of the environment increased. Reach performance was more efficient during binocular viewing, which was demonstrated by shorter reach reaction time and overall movement time. Reaching movements during the approach phase had higher peak velocity during binocular viewing. During monocular viewing reach trajectories exhibited a direction bias during the acceleration phase, which was leftward during left eye viewing and rightward during right eye viewing. This bias can be explained by the presence of esophoria in the covered eye. The grasping interval was also extended by ~20% during monocular viewing; however, the duration of the return phase after the target was picked up was comparable across viewing conditions. In conclusion, binocular vision provides important input for planning and execution of prehension movements in visually enriched environments. Binocular advantage was evident, regardless of set size or target saliency, indicating that adults plan their movements more cautiously during monocular viewing, even in relatively simple environments with a highly salient target. Nevertheless, in visually-normal adults monocular input provides sufficient information to engage in online control to correct the initial errors in movement planning.

The influence of action execution on end-state comfort and underlying movement kinematics: An examination of right and left handed participants.

People typically move in an anticipatory manner, planning the intended action in advance to minimize the energy costs associated with producing the action (e.g., Rosenbaum et al., 2009). This is exemplified behaviorally in the end-state comfort effect, which is characterized by the selection of an uncomfortable initial posture to enable a comfortable posture upon completion of the movement (Rosenbaum et al., 1990). The main objective of this study was to further investigate the end-state comfort effect in left- and right-handers (N=20). More specifically, to: (a) understand the influence of mode of action execution; and (b) delineate the role of handedness. The overturned glass task (Fischman, 1997) was used as means of assessment, where participants were asked to demonstrate picking up a glass to pour water in four modes of execution: (1) pantomime without a stimulus; (2) pantomime with image of the glass as a guide; (3) pantomime with glass as a guide; and (4) grasping the glass. End-state comfort was displayed regardless of mode of execution, hand used to complete the task or handedness group. However, kinematic analysis revealed distinct differences, highlighting how movement parameters are altered as a result the mode of action execution.

How the mode of action affects evidence of planning and movement kinematics in aging: End-state comfort in older adults

Motor deficits are commonly observed with age; however, it has been argued that older adults are more adept when acting in natural tasks and do not differ from young adults in these contexts. This study assessed end-state comfort and movement kinematics in a familiar task to examine this further. Left- and right-handed older adults picked up a glass (upright or overturned) as if to pour water in four modes of action (pantomime, pantomime with image/cup as a guide, actual grasping). With increasing age, a longer deceleration phase (in pantomime without a stimulus) and less end-state comfort (in pantomime without a stimulus and image as a guide) was displayed as the amount of contextual information available to guide movement decreased. Changes in movement strategies likely reflect an increased reliance on feedback control and demonstration of a more cautious movement. A secondary aim of this study was to assess hand preference and performance, considering conflicting reports of manual asymmetries with age. Performance differences in the Grooved Pegboard place task indicate left handers may display a shift towards right handedness in some, but not all cases. Summarizing, this study supports age-related differences in planning and control processes in a familiar task, and changes in manual asymmetries with age in left handers.

Sequential Movements: When does Binocular Vision Facilitate Object Grasping and Placing

Vision provides a rich source of spatial and temporal information about the environment and ones own actions, which is used to plan and execute upper limb movements. Previous research has shown that viewing with both eyes provides a greater advantage during the grasping phase in comparison to the reaching phase. However, most studies examined performance using a single reach-to-grasp movement. Since most of our daily activities involve sequential manipulation actions, it is important to examine hand-eye coordination during performance of these more complex actions. Therefore, we explored the role of binocular vision in a sequential task that involved precision grasping and placing a target onto a vertical needle. Six participants picked up and placed 6 beads (one at a time) onto a needle under binocular and monocular viewing conditions while eye and limb movements were recorded. The difficulty of the grasping task was manipulated by using 2 bead sizes and the kinematic analysis focused on 4 phases of the movement: approach to the bead, bead grasping, return to needle and bead placement on the needle. Therefore, our analysis allows us to delineate which component of the task (reaching for and grasping the bead vs transporting and placing the bead) benefits more from binocular vision. We found that binocular vision was most beneficial after the bead has been grasped. Movement times during the return and placement phase were significantly reduced during binocular viewing (0.6s, SE = .055s) in comparison to monocular viewing (left eye: 0.997s, SE = 0.106s; right eye: 1.136s, SE = 0.119s; p< 0.01). These results indicate that placing the bead onto a needle requires a higher level of precision and thus requires binocular visual input in comparison to the grasping phase. Further analysis will concentrate on quantifying the temporal relation between the hands and eyes during task execution. Meeting abstract presented at VSS 2015.

Motor Control Assessment using Leap Motion: Filtering Methods and Performance in Indoor and Outdoor Environments

In this paper, we describe and evaluate a filtering method designed to remove the artifacts from hand/finger kinematics acquired using the Leap Motion controller (or ‘Leap’). We report two experiments evaluating this methods’: 1) accuracy and precision compared to an established motion-tracking system (Optotrak) and 2) performance in indoor and outdoor environmental conditions. The main findings were that the filtered Leap finger output: i) compared well to motion capture systems in temporal accuracy and precision, ii) moderately well in spatial accuracy and precision, and iii) adequately in indoor settings, but not in outdoor conditions. These advances will inform further development of new tools to assess human motor control.

Object-Tool-Actor Interaction: Object Information Drives Intended Action

ABSTRACT Tool use is typically explored via actor-tool interactions. However, the target-object (that which is being acted on) may influence perceived action possibilities and thereby guide action. Three different tool-target-object pairings were tested (Experiment 1). The hammering action demonstrated the greatest sensitivity and therefore subsequently used to further investigate target-object pairings. The hammer was removed as an option and instructions were provided using pictorial (Experiment 2), written (Experiment 3), and both pictorial and written formats (Experiment 4). The designed tool is chosen when available (Experiment 1) and when removed as a choice (i.e., the hammer), participants perform the same action associated with the designed tool (i.e., hammering) regardless of instruction method (Experiments 2, 3, and 4).

How Working With a Helpful Versus Less Helpful Confederate Influences Joint-Action in a Pegboard Task

ABSTRACT Actors change their movement strategies to complement a coactors movements when performing cooperative tasks. To further investigate this topic, the authors designed a pegboard task whereby a participant-confederate pair worked together to move a peg from one side of the board to the other. The authors examined how the experience of working with a helpful confederate versus less helpful confederate influenced the participants movement behavior. Results provide evidence that participants change their movement behaviors in response to the actions of the confederate. Here the human capacity to act in such a manner exemplifies an individuals ability to utilize his or her own action system to understand others and interact to complete joint action tasks. Individuals appear to adapt their behavior to their experiences, and thus may be helpful in some contexts and less helpful in others.