Dóra Maurer: Proportions & Timing

This paper aims at re-evaluating two of Hungarian artist Dóra Mauer’s films, the video work Proportions (1979) and the 16mm film Timing (1973/80). Both films follow a rigid structure. In Proportions, Maurer uses a paper roll to compare her own body measures repeatedly; in Timing, she repeatedly folds a white linen to compare the rhythm of her arm movements. Through her use of paper and the gesture of folding, the two films can be read as references to the very origin of the term format, as coined in early letterpress printing. When the notion of format is understood as a determination of a ratio and, as such, as an indexical reference to given social relationships (Summers, 2003), these films unfold sociocultural and political meanings. The present paper traces this spectrum of meaning through the pointed inclusion of historical discourses surrounding early motion studies, the art scene in socialist Hungary in the 1970s, and early time experiments before the advent of precision clocks.

Effects of Simulated Microgravity and Hypergravity Conditions on Arm Movements in Normogravity

The human sensorimotor control has evolved in the Earth’s environment where all movement is influenced by the gravitational force. Changes in this environmental force can severely impact the performance of arm movements which can be detrimental in completing certain tasks such as piloting or controlling complex vehicles. For this reason, subjects that are required to perform such tasks undergo extensive training procedures in order to minimize the chances of failure. We investigated whether local gravity simulation of altered gravitational conditions on the arm would lead to changes in kinematic parameters comparable to the full-body experience of microgravity and hypergravity onboard a parabolic flight. To see if this would be a feasible approach for on-ground training of arm reaching movements in altered gravity conditions we developed a robotic device that was able to apply forces at the wrist in order to simulate micro- or hypergravity conditions for the arm while subjects performed pointing movements on a touch screen. We analyzed and compared the results of several kinematic parameters along with muscle activity using this system with data of the same subjects being fully exposed to microgravity and hypergravity conditions on a parabolic flight. Both in our simulation and in-flight, we observed a significant increase in movement durations in microgravity conditions and increased velocities in hypergravity for upward movements. Additionally, we noted a reduced accuracy of pointing both in-flight and in our simulation. These promising results suggest, that locally simulated altered gravity can elicit similar changes in some movement characteristics for arm reaching movements. This could potentially be exploited as a means of developing devices such as exoskeletons to aid in training individuals prior to undertaking tasks in changed gravitational conditions.

Perception of Musicality and Emotion in Signed Songs

This study investigated how signed performances express musical meaning and emotions. Deaf, Hard-of-Hearing (HoH), and hearing participants watched eight translated signed songs and eight signed lyrics with no influence of music. The participants rated these videos on several emotional and movement dimensions. Even though the videos did not have audible sounds, hearing participants perceived the signed songs as more musical than the signed lyrics. Deaf/HoH participants perceived both types of videos as equally musical, suggesting a different conception of what it means for movement to be musical. We also found that participants’ ratings of spatial height, vertical direction, size, tempo, and fluency related to the performer’s intended emotion and participants’ ratings of valence/arousal. For Deaf/HoH participants, accuracy at identifying emotional intentions was predicted by focusing more on facial expressions than arm movements. Together, these findings add to our understanding of how audience members attend to and derive meaning from different characteristics of movement in performative contexts.

Get to grips with motivation: slipping and gripping movements are biased by approach-avoidance context

People are better at approaching appetitive cues signalling reward and avoiding aversive cues signalling punishment than vice versa. This action bias has previously been shown in approach-avoidance tasks involving arm movements in response to appetitive or aversive cues. It is not known whether appetitive or aversive stimuli also bias more distal dexterous actions, such as gripping and slipping, in a similar manner. To test this hypothesis, we designed a novel task involving grip force control (gripping and slipping) to probe gripping-related approach and avoidance behaviour. 32 male volunteers, aged 18-40 years, were instructed to either grip (“approach”) or slip (”avoid”) a grip-force device with their right thumb and index finger at the sight of positive or negative images. In one version of this pincer grip task, participants were responding to graspable objects and in another version of the task they were responding to happy or angry faces. Bayesian repeated measures Analysis of variance revealed extreme evidence for an interaction between response type and cue valence (Bayes factor = 296). Participants were faster to respond in affect-congruent conditions (“approach appetitive”, “avoid aversive”) than in affect-incongruent conditions (“approach aversive”, “avoid appetitive”). This bias towards faster response times for affect-congruent conditions was present regardless of whether it was a graspable object or a face signalling valence. Since our results mirror the approach and avoidance effects previously observed for arm movements, we conclude that a tendency favouring affectively congruent cue-response mappings is an inherent feature of motor control and thus also includes precision grip.

Introduction of brain computer interface to neurologists

A brain-computer interface (BCI) is a technology that acquires and analyzes electrical signals from the brain to control external devices. BCI technologies can generally be used to control a computer cursor, limb orthosis, or word processing. This technology can also be used as a neurological rehabilitation tool for people with poor motor control. We reviewed historical attempts and methods toward predicting arm movements using brain waves. In addition, representative studies of minimally invasive and noninvasive BCI were summarized.

A-134 Agile Development of Virtual Reality Treatment for Spatial Neglect: Preliminary Usability and Feasibility

Objective Examine the usability and feasibility of a virtual reality (VR) treatment for persons with spatial neglect using head mounted display (HMD) and hand tracking technologies. Method Recruited from a rehabilitation hospital, 9 stroke survivors with spatial neglect (3 females; mean age = 64.2 years, SD = 9.1; 8 left neglect) participated in user testing for ongoing software development. Participants tested one of four customized treatment modules and completed the System Usability Scale, the Presence Questionnaire, and the Simulator Sickness Questionnaire. Feedback from participants were integrated into iterative prototype revisions. Module 1 (n = 7) required arm movements gradually reaching toward the neglected side of space, while the virtual hand appeared reaching straight ahead. Module 2 (n = 4) required head movements from the non-neglected to the neglected side. Module 3 (n = 6) involved head and arm movements towards both sides of space to collect objects. Module 4 (n = 2) was to stop approaching objects from a distance ahead. Results Despite reporting a lack of realism, participants preferred VR over conventional therapy. Participants felt comfortable and confident engaging in the virtual environment. Module 4 was more difficult than the other modules as participants required more practice to perform the task. Two participants reported Module 3 being tiresome, with one reporting mild shoulder pain and eye strain, and moderate sweating. However, all reported symptoms were temporary and resolved following a short break. Conclusion VR-based rehabilitation for spatial neglect using HMD and hand tracking technologies may be a viable treatment option for stroke survivors with spatial neglect. The modules benefited substantively from modifications based on participants’ feedback.

Contribution of arm movements to recovery after a trip in older adults.

Falls are common in daily life, and our arms play an important role in recovering balance after a trip. Although older adults fall more often with more serious consequence, there is limited research into arm movements during falls in older adults. We investigated how older adults use their arms to recover from a trip and the difference between fallers and non-fallers. Sixteen older participants walked along a walkway and were occasionally tripped using a custom tripping device. A biomechanical model used full-body marker and force-plate data to calculate the body rotation during the trip, and simulated the rotation without arms (Cut) and with transfer of the arms momentum to the body (Transfer & Cut). We only analysed the first trip, distinguishing fallers (n=5) from non-fallers (n=11). Apart from an expected increase in forward body rotation at foot touchdown in fallers, we found no significant differences between fallers and non-fallers in the effects of arm movements on trip recovery. Like earlier studies in young participants, we found that arm movements had most favourable effect in the transversal plane: by delaying the transfer of angular momentum of the arms to the body, participants rotated the tripped leg more forward thereby allowing more room for a larger recovery step. Older adults that are prone to falling might improve their recovery from a trip by learning to [further] prolong ongoing arm movement.