Modulation of motor variability related to experimental muscle pain during elbow-flexion contractions

Experimental muscle pain typically reorganizes the motor control. The pain effects may decrease when the three-dimensional force components are voluntarily adjusted, but it is not known if this could have negative consequences on other structures of the motor system. The present study assessed the effects of acute pain on the force variability during sustained elbow flexion when controlling task-related (one-dimensional) and all (three-dimensional) contraction force components via visual feedback. Experimental muscle pain was induced by bolus injection of hypertonic saline into m. biceps brachii, and isotonic saline was used as control. Twelve subjects performed sustained elbow flexion at different levels of the maximal voluntary contraction (5–30% MVC) before, during, and after the injections. Three-dimensional force components were measured simultaneously with surface electromyography (EMG) from elbow flexors and auxiliary muscles. Results showed that force variability was increased during pain compared to baseline for contractions using one-dimensional feedback (P < .05), but no significant differences were found for three-dimensional feedback. During painful contractions (1) EMG activity from m. trapezius was increased during contractions using both one-dimensional and three-dimensional feedback (P < .05), and (2) the complexity of EMG from m. triceps brachii and m. deltoid was higher for the three-dimensional feedback (P < .05). In conclusion, the three-dimensional feedback reduced the pain-related functional distortion at the cost of a more complex control of synergistic muscles.     

Reflexivity in Teams: A Review and New Perspectives

Team reflexivity posits that the extent to which teams reflect upon and adapt their functioning is positively related to team performance. While remarkable progress has been made to provide evidence of this relationship, the underlying framework is missing elements of current theoretical streams for analyzing and describing teamwork, leaving the diversity of effects of team reflexivity often untouched. In this article, we present an update for this framework, by reviewing previous research on reflexivity, addressing gaps in the literature, and revising the original model by integrating feedback and dynamic team effectiveness frameworks for describing temporal developments of reflexivity. We furthermore propose a new dimensional structure for reflexivity, relying on prior work conceptualizing teams as information-processing systems that learn and advance through social-cognitive elements. Our model is therefore not only suitable for explaining the diverse set of relationships between team reflexivity on outcomes, but also provides valuable directions for viewing reflexivity as process that takes place during both transition and action phases of teamwork. We conclude with implications for managers, identify limitations, and propose an agenda for further research into this area. This article contributes an extended perspective relevant for further theory development and for effectively managing reflexivity in teams.     

Decreasing bouts of prolonged sitting among office workers

Many workers in industrialized nations spend their day seated at a desk. Research suggests that accumulated sitting time increases risk for certain diseases (van der Ploeg, Chey, Korda, Banks, & Bauman, 2012). To reduce risk, health researchers recommend frequent standing or walking breaks during the workday. In the current study, we evaluated 3 behavioral interventions to decrease bouts of prolonged sitting among office workers. Information alone was not as effective as a treatment package that consisted of a tactile prompt, feedback, and goal setting.     

Impacts of delayed feedback on eco-driving behavior and resulting environmental performance changes

Several ways have been developed and applied to improve the environmental footprint of road transportation while contributing to a better road efficiency and safety. However, independently of these measures, the individual’s behavior as a commuter and/or as a driver is also a major issue that cannot be ignored. As a result, the aim of this paper was to assess the impacts of delayed feedback on driving performance considering indicators such as average speed, excess speeding, extreme braking and acceleration; fuel consumption and CO₂ emissions, among others. Data on driving behavior was collected over a period of 6 months through the use of an on-board device installed in 40 light-duty vehicles in the region of Lisbon, Portugal. Two driving monitoring periods of 3 months each were considered: without feedback (Phase 1) and with feedback (Phase 2). Additionally, the short-term (weekly and bi-weekly) impact of feedback on performance was also assessed.The major findings indicate that both experimental and control groups increased fuel consumption and CO₂ emissions over 5%. Both male and female drivers presented increases in these indicators with female drivers presenting higher values (up to 8%, as opposed to the 4% presented by male drivers). These results are related with increases in the number of accelerations, idling and number of small trips (below 2 km) between monitoring periods. Regarding the immediate impact of feedback on driving behavior, results indicate that when receiving negative feedback (revealing a performance decline), behavior would improve the following week. The opposite was found for positive feedback, with drivers worsening performance after being informed they had improved the previous week. Such findings might give an indication that people react differently to the feedback provided, and might depreciate the information provided when negative results are reached.     

Why doesn’t feedback correct Vierordt’s law?

Vierordt [(1868). Der zeitsinn nach versuchen. Tübingen: Laupp] observed that participants over-reproduce short durations and under-reproduce long durations within a test range of sample durations (Vierordt’s law). Similar phenomena have been reported for sensory and other processing (e.g. [Helson (1964 Helson, H. (1964). Adaptation-level theory. New York, NY: Harper &; Row. [Google Scholar]). Adaptation-level theory. New York: Harper &; Row; Stevens, and Greenbaum (1966). Regression effect in psychophysical judgment. Perception &; Psychophysics, 1, 439–446]. Performance feedback (knowledge of results) does not correct this performance distortion although it does correct other errors. In Experiment 1, I tested the hypothesis that a random presentation order of the standard durations makes feedback on one trial inappropriate for the next trial preventing correction of the Vierordt effect. In Experiment 2, participants performed two consecutive reproductions after each standard duration. Having the opportunity to immediately utilize the feedback from the first reproduction did not eliminate the Vierordt effect, although participants did attempt to correct the error on the first reproduction. In Experiment 3, the Vierordt effect was reduced in a blocked presentation design. Feedback produced more veridical performance. I conclude that the resistance of the Vierordt effect to correction by feedback may result, in part, from feedback on a given trial being misapplied to correcting performance on the next trial. Ironically, the Vierordt effect, which produced the differing directions and magnitudes of performance errors reported by the feedback, may be what prevents feedback from correcting for the Vierordt effect.     

Feedback on health status and peer popularity influences social risk decision-making processes in adolescents and young adults

Cognitive and dual-processes models, involving cognitive and socio-emotional components, for adolescents’ risky behaviour have been proposed. This study tested their predictions by manipulating the presence or absence of feedback about gains and losses in health and peer popularity in a decision-making task with peers. Risky (e.g., taking or refusing a drug) and ambiguous decisions (e.g., eating hamburger or hotdog) were examined in 256 adolescents (aged 13–14; 15–16; 17–18) and young adults (aged 19–20). Participants made more risky choices and required less decision time when receiving feedback about the negative consequences on health and positive consequences on peer popularity. Decision times were comparatively larger for risky than for safe options in late adolescence and young adulthood. Results supported the dual-processes model showing that, though late cognitive changes were observed that could eventually lead to the selection of safe options, feedback gains in peer popularity outweighed unhealthy consequences leading to risky decisions.     

Evaluating the impact of real-time coaching programs on drivers overtaking cyclists

Innovative motor insurance schemes involve the use of on-board devices to collect kinematic driving data as part of the so-called ‘Pay-How-You-Drive’ schemes, which charge premiums based on drivers’ behavior. Some of these schemes also involve on-board coaching programs, which give real-time feedback to users.Here, we aimed to investigate the influence of motor insurance on-board real-time coaching programs on drivers’ behavior while overtaking cyclists, as motor vehicle/bicycle interactions are a relevant issue in road safety. The tested programs give real-time feedback to users on their acceleration, promoting smoother and safer driving styles.Data were collected with a driving simulator experiment involving 67 young drivers. The experiment was divided into two trials: in the first, participants drove as normally as possible without receiving any type of feedback; in the second, which took place one month later, they received feedback based on their driving behavior. Using data from the first trial, participants were clustered (k-mean approximation) into two groups, according to their driving style (aggressive vs. defensive). For each group, half of the drivers received contingent positive feedback (when a smooth driving event occurred) and the other half received contingent negative feedback (when a harsh driving event occurred). Feedback was presented in the form of auditory cues (for half of one group) or as visual cues (for the others). Thus, there were eight groups based on driving style, feedback type, and feedback modality.Multiple kinematic variables were studied with mixed ANOVA, and included not only clearance distances, speeds, and acceleration, but also the chosen overtaking strategy (accelerative vs. flying). Driving style, gender, car usage, feedback type and modality were considered as factors in the analysis.Results showed that the coaching programs had a significant positive effect, in terms of safety, reducing acceleration and speeds during the overtaking and inducing drivers to adopt the safer accelerative strategy. It was also particularly effective in improving the performance of aggressive drivers. These results are of high interest for real-world applications because they were obtained with a general-purpose coaching program; conversely, it might be impractical to develop dedicate programs for specific situations such as drivers overtaking cyclists.     

Effects of normative feedback on motor learning are dependent on the frequency of knowledge of results

Studies on normative feedback have shown superior motor learning outcomes for individuals who believe that they are performing better than others through increased self-efficacy. Nevertheless, the effects of normative feedback were never dissociated from the knowledge of results (KR) provided to the learners which potentially interacts with self-efficacy as well. Thus, we investigated whether the effects of normative feedback on motor learning, associated with self-efficacy, would be dependent on the amount of KR provided. Fifty-six participants were randomly assigned to four experimental groups in terms of KR frequency (100% and 33%) and normative feedback (positive and negative). In the acquisition phase, all groups received the average KR of their performance at the end of each block of trials (True feedback) and a fake KR based on their own performance (but said to be from a group of participants who practiced the same task) (False Feedback). The False Feedback indicated better or worse performance of the participant in comparison to the fake group, depending on their experimental group. Retention tests were performed immediately and after 24 h from the acquisition phase. To measure self-efficacy, a questionnaire on participant's efficacy was applied before the first block, after each block of trials and before the retention tests. The results revealed superiority of positive normative feedback and 100% KR frequency, compared to negative normative feedback and 100% KR frequency in the 24h retention test. No difference was found between the groups with a frequency of 33% of KR (positive and negative). All groups increased self-efficacy during practice, but there was no difference between groups at any stage of the study. We conclude that the effects of normative feedback on motor learning are dependent on the KR frequency. However, they were not associated with self-efficacy.     

阈下情绪反馈对结果评价的影响及其性别差异

本研究用互动的决策游戏和脑电技术考察阈下情绪反馈对结果加工的影响。结果表明输钱相对于赢钱诱发更大的FRN/RewP和更小的P300,同时阈下愤怒反馈可以延缓赢钱之后下一次选择的反应时,并在女性被试中诱发更负的FRN/RewP, 但对反馈相关P300没有显著影响。这些结果说明阈下情绪反馈可影响决策结果评价早期的对刺激动机性意义的快速评估,但对晚期的深度评估没有显著影响,且这种影响在女性被试中更为明显。