Expectations and Beliefs in Immersive Virtual Reality Environments: Managing of Body Perception

Real and Perceived Feet Orientation Under Fatiguing and Non-Fatiguing Conditions in an Immersive Virtual Reality Environment ABSTRACT Lower limbs position sense is a complex yet poorly understood mechanism, influenced by many factors. Hence, we investigated the position sense of lower limbs through feet orientation with the use of Immersive Virtual Reality (IVR). Participants had to indicate how they perceived the real 1050 orientation of their feet by orientating a virtual representation of the feet that was shown in an IVR 1051 scenario. We calculated the angle between the two virtual feet (α-VR) after a high-knee step-in-1052 place task. Simultaneously, we recorded the real angle between the two feet (α-R) (T1). Hence, we 1053 assessed if the acute fatigue impacted the position sense. The same procedure was repeated after 1054 inducing muscle fatigue (T2) and after 10 minutes from T2 (T3). Finally, we also recorded the time 1055 needed to confirm the perceived position before and after the acute fatigue protocol. Thirty healthy 1056 adults (27.5 ± 3.8: 57% female, 43% male) were immersed in an IVR scenario with a representation 1057 of two feet. We found a mean difference between α-VR and α-R of 20.89° [95% CI: 14.67°, 27.10°] 1058 in T1, 16.76° [9.57°, 23.94°] in T2, and 16.34° [10.00°, 22.68°] in T3. Participants spent 12.59, 17.50 1059 and 17.95 seconds confirming the perceived position of their feet at T1, T2, T3, respectively. 1060 Participants indicated their feet as forwarding parallel though divergent, showing a mismatch in the 1061 perceived position of feet. Fatigue seemed not to have an impact on position sense but delayed the 1062 time to accomplish this task.The Effect of Context on Eye-Height Estimation in Immersive Virtual Reality: a Cross-Sectional Study ABSTRACT Eye-height spatial perception provides a reference to scale the surrounding environment. It is the result of the integration of visual and postural information. When these stimuli are discordant, the perceived spatial parameters are distorted. Previous studies in immersive virtual reality (IVR) showed that spatial perception is influenced by the visual context of the environment. Hence, this study explored how manipulating the context in IVR affects individuals’ eye-height estimation. Two groups of twenty participants each were immersed in two different IVR environments, represented by a closed room (Wall - W) and an open field (No Wall - NW). Under these two different conditions, participants had to adjust their virtual perspective, estimating their eye height. We calculated the perceived visual offset as the difference between virtual and real eye height, to assess whether the scenarios and the presence of virtual shoes (Feet, No Feet) influenced participants’ estimates at three initial offsets (+100 cm, +0 cm, -100 cm). We found a mean difference between the visual 1679 offsets registered in those trials that started with 100 cm and 0 cm offsets (17.24 cm [8.78; 25.69]) 1680 and between 100 cm and -100 cm offsets (22.35 cm [15.65; 29.05]). Furthermore, a noticeable mean difference was found between the visual offsets recorded in group W, depending on the presence or absence of the virtual shoes (Feet VS No Feet: -6.12 [-10.29, -1.95]). These findings describe that different contexts influenced eye-height perception.Positive Expectations led to Motor Improvement: an Immersive Virtual Reality Pilot Study ABSTRACT This pilot study tested the feasibility of an experimental protocol that evaluated the effect of different positive expectations (verbal and visual-haptic) on anterior trunk flexion. Thirty-six participants were assigned to 3 groups (G0, G+ and G++) that received a sham manoeuvre while immersed in Immersive Virtual Reality (IVR). In G0, the manouvre was paired with by neutral verbal statement. In G+ and G++ the manouvre was paired with a positive verbal statement, but only G++ received a visual-haptic illusion. The illusion consisted of lifting a movable tile placed in front of the participants, using its height to raise the floor level in virtual reality. In this way, participants experienced the perception of touching the floor, through the tactile and the virtual visual afference. The distance between fingertips and the floor was measured before, immediately after, and after 5 minutes from the different manouvres. A major difference in anterior trunk flexion was found for G++ compared to the other groups, although it was only significant compared to G0. This result highlighted the feasibility of the present study for future research on people with mobility limitations (e.g., low back pain or kinesiophobia) and the potential role of a visual-haptic illusion in modifying the performance of trunk flexion

What Physiotherapists Specialized in Orthopedic Manual Therapy Know About Nocebo-Related Effects and Contextual Factors: Findings From a National Survey

none10siopenRossettini, Giacomo; Geri, Tommaso; Palese, Alvisa; Marzaro, Chiara; Mirandola, Mattia; Colloca, Luana; Fiorio, Mirta; Turolla, Andrea; Manoni, Mattia; Testa, MarcoRossettini, Giacomo; Geri, Tommaso; Palese, Alvisa; Marzaro, Chiara; Mirandola, Mattia; Colloca, Luana; Fiorio, Mirta; Turolla, Andrea; Manoni, Mattia; Testa, Marc

Real and perceived feet orientation under fatiguing and non-fatiguing conditions in an immersive virtual reality environment

Lower limbs position sense is a complex yet poorly understood mechanism, influenced by many factors. Hence, we investigated the position sense of lower limbs through feet orientation with the use of Immersive Virtual Reality (IVR). Participants had to indicate how they perceived the real orientation of their feet by orientating a virtual representation of the feet that was shown in an IVR scenario. We calculated the angle between the two virtual feet (α-VR) after a high-knee step-in-place task. Simultaneously, we recorded the real angle between the two feet (α-R) (T1). Hence, we assessed whether the acute fatigue impacted the position sense. The same procedure was repeated after inducing muscle fatigue (T2) and after 10 min from T2 (T3). Finally, we also recorded the time needed to confirm the perceived position before and after the acute fatigue protocol. Thirty healthy adults (27.5 ± 3.8: 57% women, 43% men) were immersed in an IVR scenario with a representation of two feet. We found a mean difference between α-VR and α-R of 20.89° [95% CI: 14.67°, 27.10°] in T1, 16.76° [9.57°, 23.94°] in T2, and 16.34° [10.00°, 22.68°] in T3. Participants spent 12.59, 17.50 and 17.95 s confirming the perceived position of their feet at T1, T2, T3, respectively. Participants indicated their feet as forwarding parallel though divergent, showing a mismatch in the perceived position of feet. Fatigue seemed not to have an impact on position sense but delayed the time to accomplish this task

Constraints on the χ_(c1) versus χ_(c2) polarizations in proton-proton collisions at √s = 8 TeV

The polarizations of promptly produced χ_(c1) and χ_(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8  TeV. The χ_c states are reconstructed via their radiative decays χ_c → J/ψγ, with the photons being measured through conversions to e⁺e⁻, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χ_(c2) to χ_(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ → μ⁺μ⁻ decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum