Cognitive loading affects motor awareness and movement kinematics but not locomotor trajectories during goal-directed walking in a virtual reality environment.

The primary purpose of this study was to investigate the effects of cognitive loading on movement kinematics and trajectory formation during goal-directed walking in a virtual reality (VR) environment. The secondary objective was to measure how participants corrected their trajectories for perturbed feedback and how participants' awareness of such perturbations changed under cognitive loading. We asked 14 healthy young adults to walk towards four different target locations in a VR environment while their movements were tracked and played back in real-time on a large projection screen. In 75% of all trials we introduced angular deviations of ±5° to ±30° between the veridical walking trajectory and the visual feedback. Participants performed a second experimental block under cognitive load (serial-7 subtraction, counter-balanced across participants). We measured walking kinematics (joint-angles, velocity profiles) and motor performance (end-point-compensation, trajectory-deviations). Motor awareness was determined by asking participants to rate the veracity of the feedback after every trial. In-line with previous findings in natural settings, participants displayed stereotypical walking trajectories in a VR environment. Our results extend these findings as they demonstrate that taxing cognitive resources did not affect trajectory formation and deviations although it interfered with the participants' movement kinematics, in particular walking velocity. Additionally, we report that motor awareness was selectively impaired by the secondary task in trials with high perceptual uncertainty. Compared with data on eye and arm movements our findings lend support to the hypothesis that the central nervous system (CNS) uses common mechanisms to govern goal-directed movements, including locomotion. We discuss our results with respect to the use of VR methods in gait control and rehabilitation

Substitutional Reality System: A Novel Experimental Platform for Experiencing Alternative Reality

We have developed a novel experimental platform, referred to as a substitutional reality (SR) system, for studying the conviction of the perception of live reality and related metacognitive functions. The SR system was designed to manipulate people's reality by allowing them to experience live scenes (in which they were physically present) and recorded scenes (which were recorded and edited in advance) in an alternating manner without noticing a reality gap. All of the naïve participants (n = 21) successfully believed that they had experienced live scenes when recorded scenes had been presented. Additional psychophysical experiments suggest the depth of visual objects does not affect the perceptual discriminability between scenes, and the scene switch during head movement enhance substitutional performance. The SR system, with its reality manipulation, is a novel and affordable method for studying metacognitive functions and psychiatric disorders

Congruent Visuo-Tactile Feedback Facilitates the Extension of Peripersonal Space

Effective tool use relies on the integration of multisensory signals related to one's body and the tool. It has been shown that active tool use results in an extension of peripersonal space, i. e., the space directly surrounding the human body. In the present studies we investigated whether the mere observation of a virtual tool that could be manipulated via a haptic robotic interface would also affect the perception of peripersonal space. Participants passively observed a tool being used (Study 1) and received simple visuotactile feedback related to the tool (Study 2). We assessed the extension of peripersonal space by using the crossmodal congruency task, which measures the interference of observed visual distractors presented at the tool on judgments about tactile stimuli presented to the fingers. We found that passive observation of tool use resulted in a crossmodal congruency effect for both crossed and uncrossed arm/tool use postures (Study 1). This effect was even more pronounced when participants were presented with simple visuo-tactile feedback during the observation phase (Study 2). These findings suggest that additional visuotactile feedback enhances the integration of the tools into the body schema. We discuss the relevance of these findings for the development of surgical robotics, virtual tool use and for motor rehabilitation

Immersive Episodic Memory Assessment with 360\ub0 Videos: The Protocol and a Case Study

Episodic memory has been conceptualized as the memory for personal events with specific spatiotemporal components. The assessment of episodic memory is usually conducted by means of verbal recall tasks, in which the individual is required to repeat what (s)he remembers from a previously presented verbal material (either single words or a brief story). However, the need of a more ecological approach to memory assessment led researchers to investigate the potential use of 360\ub0 videos as a suitable tool to present real life scenes to be remembered. The present study presents the protocol of the assessment of episodic memory employing five 360\ub0 video that represent interpersonal, emotional experiences known to be altered in psychopathological conditions. Furthermore, a case study in which the assessment protocol is applied to a patient with Borderline Personality Disorder is described. The results of the case study seem to indicate that our 360\ub0 videos are able to detect anomalies in remembering the behaviors displayed, the connected emotion together with details regarding the \u201cwhere\u201d and \u201cwhen\u201d components of the episodic recall