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This study compares two groups of university students with differing instructions participating in an object drawing task as a part of an art therapy-based self-help online intervention. The intervention aimed to help participants enhance positive mood and subjective feeling of self-control and reduce negative mood. The object task contained suggestive elements in the instructions similar to self-hypnosis with an indirect and a direct way of formulation. Quantitative (positive affect and negative affect scale and Self-Assessment Manikin scale) and qualitative methods (text and picture rating) were used to investigate the difference between the outcome effects on the two groups. The results found a significant decrease in negative mood for indirect suggestion, while a significant increase of positive mood for the direct suggestion condition. Based on qualitative analyses, findings indicated that hidden implications in the art-making instructions modified the chosen imaginary and emotional changes related to art-making. Suggestions in the instructions can make a difference in one's mood and this should also be considered while designing guidelines for self-hypnosis.

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Different types of feedback are used during gait training in children with cerebral palsy (CP), including verbal (VB) and virtual reality (VR) feedback. Previous studies on VR feedback showed positive effects on the targeted gait parameter. However, both positive and negative side effects on other parameters were seen as well. The literature on the effect of VB feedback is lacking and, to our knowledge, both feedback methods have not yet been compared. In this monocentric study with a single-session intervention protocol, children with CP completed a training session on the Gait Real-Time Analysis Interactive Lab (GRAIL) and received both VB and VR feedback on hip extension, in randomized order. Outcome parameters were continuous gait curves of sagittal kinematics and hip kinetics, specific features of hip angle and moment, sagittal gait variable scores and gait profile scores. Improvement of the targeted gait parameter was seen both after VB and VR feedback, with a small advantage for VR over VB feedback. Furthermore, positive side effects on knee and ankle sagittal kinematics were seen. However, the overall gait profile score did not improve, most likely due to negative compensatory strategies. In conclusion, children with CP can adapt gait in response to both VB and VR feedback, with VR feedback producing a slightly better effect. Due to secondary effects on parameters other than the targeted parameter, the overall gait did not improve.

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LAY ABSTRACT: Individuals with autism spectrum disorder can find behavioural flexibility challenging, often exhibited in terms of repetitive behaviours or restricted ranges of interests and activities. An inability to shift efficiently from one situation to another is connected with problems in daily life, and identifying factors associated with this ability may help develop teaching strategies to improve behavioural flexibility. Some existing findings imply shifting performance for individuals with autism spectrum disorder is better with nonverbal, compared to verbal, feedback - even for those with strong verbal abilities. Unfortunately, there are few behavioural examinations that further explore these findings, which is the aim of this study. In this study, 28 children with a diagnosis of autism spectrum disorder and 28 typically developing children matched on cognitive and verbal abilities learned to sort cards according to one out of a possible three dimensions (colour, shape and number), and then had to relearn the sorting rule. One group of typically developing children, and one group of autism spectrum disorder children, received verbal feedback on their performance, and one group received nonverbal feedback. Children with autism spectrum disorder learned an initial categorisation rule as fast as matched typically developing children, and there was little difference in the impact of the type of feedback on acquisition. However, on shifting the classification rule, children with autism spectrum disorder showed slower rates of learning the new rule, which was worse when verbal feedback was used compared to nonverbal feedback. This finding has implications for the interpretations of set-shifting performance and for classroom use of feedback strategies.

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Background and Objectives: Verbal encouragement (VE) can be used to enhance performance in several sports, even though no studies have been conducted among swimmers and only a few effects have been reported in elite athletes. Besides influencing motor performance, VE is also known to enhance the physical load, thus potentially increasing the probability of developing fatigue. With this in mind, this study aimed to explore the effects of VE in swimmers in order to fill in the knowledge gap concerning the aquatic environment. Materials and Methods: Each athlete swam a maximal 200 m freestyle trial under two different conditions: one trial with VE and the other without VE. The two main outcome measures were: (1) performance velocity (m/s); and (2) muscle fatigue, investigated by means of surface electromyography. Sixty swimmers were recruited, aged 18.63 ± 3.46 years (median 18 years), 28 men (47%), and 32 women (53%), with 7.03 ± 3.9 years of experience. Results: With VE, performance significantly improved in the swim trial (p < 0.001, effect size (ES) −0.95, large). When breaking the results down into the first half (first (0−100 m) vs. the second half (100−200 m)), the ES was large in the first part (−1.11), indicating an improvement in performance. This worsened, however, in the second part of the trial (ES 0.63). In the multivariate analysis, years of experience were found to be a significant predictor of the change in overall performance (p = 0.011). There was a significant increase in muscle fatigue induced by VE, overall, and during the second half, but not during the first half of the trial. Conclusions: The present study indicates that VE during a middle-distance event (200 m) increases performance most in swimmers with little experience. However, it has a negative impact on fatigue.

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Pelvic floor muscle training (PFMT) has been recommended as the first choice as one of the effective methods for preventing and improving urinary incontinence (UI). We aimed to determine whether pressure biofeedback unit training (PBUT) improves short term and retention performance of pelvic floor muscle contraction. The muscle activities of the external oblique (EO), transversus/internal oblique (TrA/IO), multifidus (MF) and the bladder base displacement were measured in the verbal feedback group (n = 10) and PBU group (n = 10) three times (baseline, post-training, and at the 1-week follow-up). Surface electromyographic activity was recorded from the EO, TrA/IO, and MF muscles. The bladder base displacement was measured using ultrasound. The results were analyzed using two way mixed ANOVA. The bladder base displacement may have elevated more in the PBU group than in the verbal feedback group due to decreased TrA/IO activity. These findings indicate that PBUT is a better method than verbal feedback training.

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[This corrects the article DOI: 10.3389/frai.2021.703504.].

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Trust is the foundation of successful human collaboration. This has also been found to be true for human-robot collaboration, where trust has also influence on over- and under-reliance issues. Correspondingly, the study of trust in robots is usually concerned with the detection of the current level of the human collaborator trust, aiming at keeping it within certain limits to avoid undesired consequences, which is known as trust calibration. However, while there is intensive research on human-robot trust, there is a lack of knowledge about the factors that affect it in synchronous and co-located teamwork. Particularly, there is hardly any knowledge about how these factors impact the dynamics of trust during the collaboration. These factors along with trust evolvement characteristics are prerequisites for a computational model that allows robots to adapt their behavior dynamically based on the current human trust level, which in turn is needed to enable a dynamic and spontaneous cooperation. To address this, we conducted a two-phase lab experiment in a mixed-reality environment, in which thirty-two participants collaborated with a virtual CoBot on disassembling traction batteries in a recycling context. In the first phase, we explored the (dynamics of) relevant trust factors during physical human-robot collaboration. In the second phase, we investigated the impact of robot's reliability and feedback on human trust in robots. Results manifest stronger trust dynamics while dissipating than while accumulating and highlight different relevant factors as more interactions occur. Besides, the factors that show relevance as trust accumulates differ from those appear as trust dissipates. We detected four factors while trust accumulates (perceived reliability, perceived dependability, perceived predictability, and faith) which do not appear while it dissipates. This points to an interesting conclusion that depending on the stage of the collaboration and the direction of trust evolvement, different factors might shape trust. Further, the robot's feedback accuracy has a conditional effect on trust depending on the robot's reliability level. It preserves human trust when a failure is expected but does not affect it when the robot works reliably. This provides a hint to designers on when assurances are necessary and when they are redundant.

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Studies indicate that providing subjects with positiveaugmented feedback (PAF) enhances motor learning and performance compared to negative- (NAF), or no-feedback. However, in the majority of these studies, the performance feedback was provided relative to a peer-group (e.g., "your performance is higher/lower than the norm"). Here we examined how different, and less explored types of PF and NF, influenced repeated force production of 22 resistance-trained subjects (50%-males). On three occasions, subjects completed 12 isometric maximal voluntary contractions (MVC) with their elbow flexors, while electromyography (EMG) was collected from their biceps and triceps brachii muscles. After every second repetition, subjects received either PF (e.g., "You are looking great."), NF (e.g., "You are not trying."), or no-feedback. All measurements were normalized to pre-test MVCs and reported aspercentages. Subjects applied greater forces in the NF condition compared to the PF (4.3%, 95%CI: 2.8, 5.8) and no-feedback (7.9%, 95%CI: 6.4, 9.4) conditions. Similarly, subjects demonstrated greater biceps EMG activity in the NF compared to the PF (6.6%, 95%CI: 3.7, 9.4) and no-feedback (2.8%, 95%CI: 9.9, 15.6) conditions. We speculate that NF can lead subjects to exert greater forces bysignaling that their efforts are lacking. These results indicate that under some circumstances, NF can have practical benefits over no-feedback and even PF; however, we note that NF should be delivered with caution since it may also hinder motivation and self-efficacy over time.

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Wearable sensing technology is a new way to deliver corrective feedback. It is highly applicable to gait rehabilitation for persons with Parkinson's disease (PD) because feedback potentially engages spared neural function. Our study characterizes participants' motor adaptation to feedback signaling a deviation from their normal cadence during prolonged walking, providing insight into possible novel therapeutic devices for gait re-training. Twenty-eight persons with PD (15 with freezing, 13 without) and 13 age-matched healthy elderly (HE) walked for two 30-minute sessions. When their cadence varied, they heard either intelligent cueing (IntCue: bouts of ten beats indicating normal cadence) or intelligent feedback (IntFB: verbal instruction to increase or decrease cadence). We created a model that compares the effectiveness of the two conditions by quantifying the number of steps needed to return to the target cadence for every deviation. The model fits the short-term motor responses to the external step inputs (collected with wearable sensors). We found some significant difference in motor adaptation among groups and subgroups for the IntCue condition only. Both conditions were instead able to identify different types of responders among persons with PD, although showing opposite trends in their speed of adaptation. Increasing rather than decreasing the pace appeared to be more difficult for both groups. In fact, under IntFB the PD group required about seven steps to increase their cadence, whereas they only needed about three steps to decrease their cadence. However, it is important to note that this difference was not significant; perhaps future work could include more participants and/or more sessions, increasing the total number of deviations for analysis. Notably, a significant negative correlation, r = -0.57 (p-value = 0.008), was found between speed of adaptation and number of deviations during IntCue, but not during IntFB, suggesting that, for people who struggle with gait, such as those with PD, verbal instructions rather than metronome beats might be more effective at restoring normal cadence. Clinicians and biofeedback developers designing novel therapeutic devices could apply our findings to determine the optimal timing for corrective feedback, optimizing gait rehabilitation while minimizing the risk of cue-dependency.

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OBJECTIVES: The ability to perform a correct pelvic floor muscle contraction (PFMC) is necessary to start pelvic floor muscle training after delivery. COMMOV are "c"ontractions of "o"ther "m"uscles (m. rectus abdominus, the gluteal muscles, and the adductors), and other "mov"ements (pelvic tilt, breath holding, and straining) performed in addition to or instead of the PFMC. COMMOV are probably the most common errors in attempt to contract the pelvic floor muscles during the first days after delivery. The aims of this study were to observe the prevalence of COMMOV, to investigate whether COMMOV influence the ability to perform a PFMC, and whether verbal instructions are effective to unlearn the COMMOV postpartum. STUDY DESIGN: A Prospective Observational Study was performed in women during the first through sixth day postpartum. PFMC and COMMOV were evaluated with visual observation. Women who did not show correct isolated PFMC received verbal instructions and were re-evaluated. Interobserver variability and agreement were calculated. Chi-square, Kappa, Risk Ratio, and McNemar were used. RESULTS: A total of 382 women participated, 2.36 (±1.2) days postpartum. Twohundred sixteen, 57%, CI (52-62%), showed COMMOV. The chance to perform a correct PFMC was 2.65 times higher without COMMOV (p=0.0001). Verbal feedback was effective (57% reduced to 3%) to abandon COMMOV during PFMC. CONCLUSION: COMMOV are common errors performed during attempts to contract the pelvic floor muscles after delivery. They can reduce the ability to contract the pelvic floor muscles, but can easily been unlearned with visual observation and verbal feedback.

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Rhythmic auditory cueing is a well-accepted tool for gait rehabilitation in Parkinson's disease (PD), which can now be applied in a performance-adapted fashion due to technological advance. This study investigated the immediate differences on gait during a prolonged, 30 min, walk with performance-adapted (intelligent) auditory cueing and verbal feedback provided by a wearable sensor-based system as alternatives for traditional cueing. Additionally, potential effects on self-perceived fatigue were assessed. Twenty-eight people with PD and 13 age-matched healthy elderly (HE) performed four 30 min walks with a wearable cue and feedback system. In randomized order, participants received: (1) continuous auditory cueing; (2) intelligent cueing (10 metronome beats triggered by a deviating walking rhythm); (3) intelligent feedback (verbal instructions triggered by a deviating walking rhythm); and (4) no external input. Fatigue was self-scored at rest and after walking during each session. The results showed that while HE were able to maintain cadence for 30 min during all conditions, cadence in PD significantly declined without input. With continuous cueing and intelligent feedback people with PD were able to maintain cadence (p = 0.04), although they were more physically fatigued than HE. Furthermore, cadence deviated significantly more in people with PD than in HE without input and particularly with intelligent feedback (both: p = 0.04). In PD, continuous and intelligent cueing induced significantly less deviations of cadence (p = 0.006). Altogether, this suggests that intelligent cueing is a suitable alternative for the continuous mode during prolonged walking in PD, as it induced similar effects on gait without generating levels of fatigue beyond that of HE.

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The purpose of this Letter was to investigate the influence of real-time verbal feedback to optimise push arc during over ground manual wheelchair propulsion. Ten healthy non-wheelchair users pushed a manual wheelchair for a distance of 25 m on level paving, initially with no feedback and then with real-time verbal feedback aimed at controlling push arc within a range of 85°-100°. The real-time feedback was provided by a physiotherapist walking behind the wheelchair, viewing real-time data on a tablet personal computer received from the Sensewheel, a lightweight instrumented wheelchair wheel. The real-time verbal feedback enabled the participants to significantly increase their push arc. This increase in push arc resulted in a non-significant reduction in push rate and a significant increase in peak force application. The intervention enabled participants to complete the task at a higher mean velocity using significantly fewer pushes. This was achieved via a significant increase in the power generated during the push phase. This Letter identifies that a lightweight instrumented wheelchair wheel such as the Sensewheel is a useful adjunct to wheelchair skills training. Targeting the optimisation of push arc resulted in beneficial changes in propulsion technique.

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The present research attempts to ascertain the impact of immediate verbal feedback (IVF) on modifications of stroke length (SL). In all swimming styles, stroke length is considered an essential kinematic parameter of the swimming cycle. It is important for swimming mechanics and energetics. If SL shortens while the stroke rate (SR) remains unchanged or decreases, the temporal-spatial structure of swimming is considered erroneous. It results in a lower swimming velocity. Our research included 64 subjects, who were divided into two groups: the experimental - E (n=32) and the control - C (n=32) groups. A pretest and a post-test were conducted. The subjects swam the front crawl over the test distance of 25m at Vmax. Only the E group subjects were provided with IVF aiming to increase their SL. All tests were filmed by two cameras (50 samples•s-1). The kinematic parameters of the swimming cycle were analyzed using the SIMI Reality Motion Systems 2D software (SIMI Reality Motion Systems 2D GmbH, Germany). The movement analysis allowed to determine the average horizontal swimming velocity over 15 meters. The repeated measures analysis of variance ANOVA with a post-hoc Tukey range test demonstrated statistically significant (p<0.05) differences between the two groups in terms of SL and swimming velocity. IVF brought about a 6.93% (Simi method) and a 5.09% (Hay method) increase in SL, as well as a 2.92% increase in swimming velocity.