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- ItemPerception of safe horizontal reaching distance changes with repetitive occupational loading in novice lifters(Elsevier, 2015) McCubbing, Dustin C.; Shan, Gongbing; Gonzalez, Claudia L. R.; Awosoga, Olu A.; Doan, Jon B.Safe work behaviours rely on accurate perceptions of injury risks, and workers who have a misperception of risk can be injured. Despite the importance of perception-action coupling, little is known about modification of those perceptions with changing physical or cognitive STATE. It is hypothesized that changing values for perceived affordances could evidence these modifications. A better understanding of how worker characteristics (e.g., level of fatigue) affect perceptions of affordance and their corresponding behaviours, may help when developing strategies for ergonomic best practices, particularly in manual material handling (MMH) activities. The aim of this study was to compare safe perceptions of affordance from workers that completed repetitive STATE loading. Seventy-five novice MMH workers (23 male; mean age = 21.43, SD = 3.24) made perceived affordances of their safest horizontal reaching distance (acceptable limit) to complete a model task. STATE loading consisted of physical or cognitive fatigue or a control. The levels of fatigue were assessed at five-minute intervals using Ratings of Perceived Exertion (RPE) values and Multi-Fatigue Inventory (MFI) values, respectively. A significant main effect of TIME indicated a decrease of perceived safest reaching distance observed from baseline through subsequent measurements (p<.001). The magnitude of these changes did not differ significantly between groups, suggesting that general learning more than specific STATE loading may be a major contributor to modification of affordance perceptions. However, it remains important to consider TIME and STATE influences on perceptions for safe occupational handling. Novice workers’ initial perceptions of safe working affordance may put them at risk for soft tissue injury. Physical and cognitive loading similarly affect perceived safe affordances.
- ItemArticulation speaks to executive function: an investigation in 4- to 6-year olds(Frontiers Media, 2018) Netelenbos, Nicole; Gibb, Robbin L.; Li, Fangfang; Gonzalez, Claudia L. R.Executive function (EF) and language learning play a prominent role in early childhood development. Empirical research continues to point to a concurrent relation between these two faculties. What has been given little attention, however, is the association between EF and speech articulation abilities in children. This study investigated this relation in children aged 4–6 years. Signiﬁcant correlations indicated that children with better EF [via parental report of the Behavior Rating Inventory of Executive Function (BRIEF)inventory] exhibited stronger speech sound production abilities in the articulation of the “s” and “sh” sounds. Furthermore, regression analyses revealed that the Global Executive Composite (GEC) of EF as measured by the BRIEF, served as a predictor for speech sound proﬁciency and that speech sound proﬁciency served as a predictor for the GEC. Together, these results demonstrate the imbricated nature of EF and speech sound production while bearing theoretical and practical implications. From a theoretical standpoint, the close link between EF and speech articulation may indicate a common ontogenetic pathway. From a practical perspective, the results suggest that children with speech difﬁculties could be at higher risk for EF deﬁcits.
- ItemEvidence for right-handed feeding biases in a left-handed population(Taylor & Francis, 2015) Flindall, Jason W.; Stone, Kayla D.; Gonzalez, Claudia L. R.We have recently shown that actions with similar kinematic requirements but different end-state goals may be supported by distinct neural networks. Specifically, we demonstrated that when right-handed individuals reach-to-grasp food items with intent to eat, they produce smaller maximum grip apertures (MGAs) than when they grasp the same item with intent to place it in a location near the mouth. This effect was restricted to right-handed movements; left-handed movements showed no difference between tasks. The current study investigates whether (and to which side) the effect may be lateralized in left-handed individuals. Twenty-one self-identified left-handed participants grasped food items of three different sizes while grasp kinematics were captured via an Optotrak Certus motion capture array. A main effect of task was identified wherein the grasp-to-eat action generated significantly smaller MGAs than did the grasp-to-place action. Further analysis revealed that similar to the findings in right-handed individuals, this effect was significant only during right-handed movements. Upon further inspection however, we found individual differences in the magnitude and direction of the observed lateralization. These results underscore the evolutionary significance of the grasp-to-eat movement in producing population-level right-handedness in humans as well as highlighting the heterogeneity of the left-handed population.
- ItemHand preference across the lifespan: effects of end-goal, task nature, and object location(Frontiers Media, 2015) Gonzalez, Claudia L. R.; Flindall, Jason W.; Stone, Kayla D.In the present study we investigate age-related changes in hand preference for grasping and the influence of task demands on such preference. Children (2–11), young-adults (17–28) and older-adults (57–90 ) were examined in a grasp-to-eat and a grasp-to-construct task. The end-goal of these tasks was different (eat vs.construct) as was the nature of the task(unimanual vs. bimanual). In both tasks,ipsilateral and contralateral grasps were analyzed. Results showed a right-hand preference that did not change with age. Across the three age groups, a more robust right-hand preference was observed for the unimanual, grasp-to-eat task. To disentangle if the nature (unimanual) or the end-goal (grasp-to-eat) was the driver of the robust right-hand preference,a followup experiment was conducted.Young-adult participants completed a unimanual grasp-to-place task. This was contrasted with the unimanual grasp-to-eat task and the bimanual grasp-to-construct task.Rates of hand preference for the grasp-to-eat task remained the highest when compared to the other two grasping tasks. Together, the results demonstrate that hand preference remains stable from childhood to older adulthood, and they suggest that a left hemisphere specialization exists for grasping, particularly when bringing food to the mouth.
- ItemSpeech in action: degree of hand preference for grasping predicts speech articulation competence in children(Frontiers Media, 2014) Gonzalez, Claudia L. R.; Li, Fangfang; Mills, Kelly J.; Rosen, Nicole; Gibb, Robbin L.Degree of lateralization for grasping predicts the maturity of the language production system in young, typically-developing children. In this report we provide compelling evidence for the relationship between right hand grasp-to-mouth (i.e.,feeding) movements and language development. Specifically, we show that children (4–5years old) who are more right-hand lateralized in picking up small food items for consumption show enhanced differentiation of the “s” and “sh” sounds. This result suggests that left hemisphere control of hand-to-mouth gestures may have provided an evolutionary platform for the development of language. The current investigation presents the exciting possibility that early right hand-to-mouth training could accelerate the development of articulation skills.
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