No evidence for top-down expertise effects on action perception in sprinters using static images.

Athletes have been found to demonstrate a superior ability to detect subtle variations in dynamic displays (e.g., point-light displays and videos) depicting expert actions compared to non-athletes. The current study aimed to determine whether this advantage also exists when dynamic information is unavailable (i.e., using static images). Using a staircase procedure, two frames from a video depicting an athlete either walking (everyday action) or performing a sprint start (expert action) were presented, and athletes (sprinters) and non-athletes were asked to indicate whether the images were identical or different. We examined whether presenting the images sequentially (temporal task) or simultaneously (spatial task) influenced participants' discrimination performance. We predicted that the sprinters would outperform the non-sprinters in the spatial task as body postures could be compared directly but not in the temporal task due to larger representational momentum effects for athletes. Contrary to our hypotheses, the sprinters and non-sprinters performed similarly in all tasks and conditions. In line with the prediction that representational momentum may impair performance, participants' thresholds were lower for the spatial than the temporal task. However, post-hoc analysis suggested that this effect is likely to be better explained by a task order effect whereby participants who completed the temporal task first exhibited an advantage in the spatial task, while there were no performance differences for participants who completed the opposite task order. In sum, our results provide no evidence for the idea that motor expertise affects action perception (i.e., perceptual resonance) in a simple psychophysical task employing static images.

Action Perception in Athletes: Expertise Facilitates Perceptual Discrimination.

Prior research has demonstrated that athletes outperform non-athletes on action perception tasks involving anticipation of sport-related actions. We conducted two experiments to determine whether this advantage persists on tasks without anticipation and/or transfers to non-sport actions. In Experiment 1, motor experts (sprinters) and non-experts were shown two consecutive videos of an athlete either walking or sprinting. The participants' task was to indicate whether the videos were identical or different. The sprinters were more accurate in these judgments than non-experts, indicating that their athleticism was associated with motor expertise that enhanced their perception of both expert and everyday actions. Further analysis revealed that participants who reported basing their decisions on a specific and informative cue (i.e., the distance between where the athlete's foot landed and a line on the track) outperformed those who did not. However, the sprinters benefitted more from using this cue than the non-sprinters. In Experiment 2, we assessed whether non-experts' performance improved if the number of available cues was reduced to make the informative cue easier to identify. Non-experts completed the same task as in Experiment 1, with half of the participants viewing the upper part of the athletes' body and the other half viewing the lower part containing the informative cue. However, the non-experts still did not reliably identify the cue, and performance did not vary between the two non-expert sub-groups. The results of these experiments suggest that motor expertise indirectly affects action perception by improving experts' ability to identify and use informative cues.

Investigating coaches' recognition of symptoms of eating disorders in track athletes.

Objective: To determine the extent to which athletics coaches can identify evidence of an eating disorder in track athletes and what treatment advice they would provide. Methods: Vignettes depicting athletes portraying symptoms consistent with anorexia nervosa (AN) and bulimia nervosa (BN) were developed and used to survey 185 UK and Irish athletics coaches (and a community sample of 105 non-coaches) regarding their ability to recognise and respond to symptoms of an eating disorder. Results: Coaches were no more likely than the community sample to correctly identify an eating disorder but were more likely to suggest professional treatment for an athlete experiencing symptoms of AN (OR 1.82, 95% CI 1.02 to 3.29). For both eating disorders, higher levels of mental health literacy (AN: OR 1.06, 95% CI 1.02 to 1.11, BN: OR 1.08, 95% CI 1.04 to 1.14) and more years of coaching experience (AN: OR 1.12, 95% CI 1.03 to 1.24, BN: OR 1.07, 95% CI 1.01 to 1.16) also increased the likelihood of suggesting professional help. When considering the whole sample, participants were more likely to correctly identify an eating disorder (OR 4.67, 95% CI 2.66 to 8.20) and suggest professional treatment for AN than BN (OR 1.76, CI 1.04 to 2.97). Further, symptoms of AN were more likely to be correctly identified in female than male athletes (OR 2.26, 95% CI 1.28 to 4.06). Conclusions: Although coaches were more likely than community members to recommend professional treatment to an athlete exhibiting symptoms of an eating disorder, they were no more likely to correctly identify an eating disorder in the first instance. Further work is required to enhance coaches' capacity to identify symptoms of eating disorders to ensure athletes receive appropriate interventions.

Bimanual Grasping Adheres to Weber's Law.

Weber's law states that our ability to detect changes in stimulus attributes decreases linearly with their magnitude. This principle holds true for many attributes across sensory modalities but appears to be violated in grasping. One explanation for the failure to observe Weber's law in grasping is that its effect is masked by biomechanical constraints of the hand. We tested this hypothesis using a bimanual task that eliminates biomechanical constraints. Participants either grasped differently sized boxes that were comfortably within their arm span (action task) or estimated their width (perceptual task). Within each task, there were two conditions: One where the hands' start positions remained fixed for all object sizes (meaning the distance between the initial and final hand-positions varied with object size), and one in which the hands' start positions adapted with object size (such that the distance between the initial and final hand-position remained constant). We observed adherence to Weber's law in bimanual estimation and grasping across both conditions. Our results conflict with a previous study that reported the absence of Weber's law in bimanual grasping. We discuss potential explanations for these divergent findings and encourage further research on whether Weber's law persists when biomechanical constraints are reduced.

Temporal-order judgement task suggests chronological action representations in motor experts and non-experts.

Motor priming studies have suggested that human movements are mentally represented in the order in which they usually occur (i.e., chronologically). In this study, we investigated whether we could find evidence for these chronological representations using a paradigm which has frequently been employed to reveal biases in the perceived temporal order of events-the temporal-order judgement task. We used scrambled and unscrambled images of early and late movement phases from an everyday action sequence ("stepping") and an expert action sequence ("sprinting") to examine whether participants' mental representations of actions would bias their temporal-order judgements. In addition, we explored whether motor expertise mediated the size of temporal-order judgement biases by comparing the performances of sprinting experts with those of non-experts. For both action types, we found significant temporal-order judgement biases for all participants, indicating that there was a tendency to perceive images of human action sequences in their natural order, independent of motor expertise. Although there was no clear evidence that sprinting experts showed larger biases for sprinting action sequences than non-experts, considering sports expertise in a broader sense provided some tentative evidence for the idea that temporal-order judgement biases may be mediated by more general motor and/or perceptual familiarity with the running action rather than specific motor expertise.