Postural adjustment as a function of scene orientation

2021 ◽  
Author(s):  
Kanon Fujimoto ◽  
Hiroshi Ashida
Keyword(s):  
Postural Control ◽  
Visual Cues ◽  
Head Tilt ◽  
Visual Orientation ◽  
Postural Adjustment ◽  
Postural Response ◽  
Everyday Objects ◽  
Head Mounted Display ◽  
Visual Vertical ◽  
Vector Sum

Visual orientation plays an important role in postural control, but the specific characteristics of postural response to orientation remain unknown. In this study, we investigated the relationship between postural response and the subjective visual vertical (SVV) as a function of scene orientation. We presented a virtual room including everyday objects through a head mounted display and measured head tilt. The room orientation varied from 165° left to 180° right in 15° increments. In a separate session, we also conducted a rod adjustment task to record the participant’s SVV in the tilted room. We applied a weighted vector sum model to head tilt and SVV error, and obtained the weight of three visual cues to orientation: frame, horizon and polarity cues. We found substantial contributions of all visual cues to head tilt and SVV error. For SVV error, frame cues made the largest contribution, whereas polarity contribution made the smallest. Head tilt tended to follow a similar pattern to SVV error, but the pattern was unclear. These findings suggest that multiple visual cues to orientation are involved in postural control, and imply different representations of environmental coordinates across postural control and verticality perception.

Visual Orientation as a Function of Head Tilt

1969 ◽  
Vol 29 (2) ◽  
pp. 573-574 ◽  
Author(s):  
N. J. Wade
Keyword(s):  
Head Tilt ◽  
Visual Orientation ◽  
Visual Vertical ◽  
Gravitational Vertical

The visual vertical was measured in two experiments for head tilts from 40° left to 40° right in 10° intervals. For all tilts the visual vertical was located on the opposite side of the gravitational vertical to tilt (E-effect), with maximum values at 30° left and 40° right tilt.

scholarly journals Larger head displacement to optic flow presented in the lower visual field.

2019 ◽  
Author(s):  
Kanon Fujimoto ◽  
Hiroshi Ashida
Keyword(s):  
Visual Field ◽  
Postural Control ◽  
Field Condition ◽  
Optic Flow ◽  
Postural Adjustment ◽  
Lower Visual Field ◽  
Postural Response ◽  
Head Displacement ◽  
Upper Visual Field ◽  
Self Motion

Optic flow that simulates self-motion often produces postural adjustment. Although literature suggested that human postural control considerably depends on visual inputs from the lower field in the environment, effects of the vertical location of optic flow are not well investigated on postural response. Here, we examined whether optic flow presented in the lower visual field produces a stronger postural response than optic flow in the upper visual field. Either expanding or contracting the optic flow was presented in three visual locations (upper, lower, and full visual fields) on an Oculus Rift head-mounted display. Head displacement and vection strength was measured. Results showed larger head displacement under the optic flow presentation in the lower visual field, than in the upper visual field, but only for the early period of the presentation of the contracting optic flow. Full visual field condition also produced larger head displacement than the upper visual field condition, but for contraction only. Vection was stronger for the lower visual field than the upper visual field, stronger for full visual field than upper and lower visual field. Our findings support the notion that more ecologically relevant information has a more important role in human postural control and self-motion perception.

Underestimation of self-tilt increases in reduced gravity conditions

2021 ◽  
pp. 1-8
Author(s):  
Arjan J. H. Meskers ◽  
Mark M. J. Houben ◽  
Helena J. M. Pennings ◽  
Gilles Clément ◽  
Eric Groen
Keyword(s):  
Parabolic Flight ◽  
Head Tilt ◽  
Body Axis ◽  
Reduced Gravity ◽  
Head Mounted Display ◽  
Longitudinal Body Axis ◽  
Partial Gravity ◽  
Visual Vertical ◽  
Regression Slopes ◽  
Head Roll

BACKGROUND: During large angles of self-tilt in the roll plane on Earth, measurements of the subjective visual vertical (SVV) in the dark show a bias towards the longitudinal body axis, reflecting a systematic underestimation of self-tilt. OBJECTIVE: This study tested the hypothesis that self-tilt is underestimated in partial gravity conditions, and more so at lower gravity levels. METHODS: The SVV was measured in parabolic flight at three partial gravity levels: 0.25, 0.50, and 0.75 g. Self-tilt was varied amongst 0, 15, 30, and 45 deg, using a tiltable seat. The participants indicated their SVV by setting a linear array of dots projected inside a head mounted display to the perceived vertical. The angles of participants’ body and head roll tilt relative to the gravito-inertial vertical were measured by two separate inertial measurement units. RESULTS: Data on six participants were collected. Per G-level, a regression analysis was performed with SVV setting as dependent variable and head tilt as independent variable. The latter was used instead of chair tilt, because not all the participants’ heads were aligned with their bodies. The estimated regression slopes significantly decreased with smaller G-levels, reflecting an increased bias of the SVV towards the longitudinal body axis. On average, the regression slopes were 0.95 (±0.38) at 0.75 g; 0.84 (±0.22) at 0.5 g; and 0.63 (±0.33) at 0.25 g. CONCLUSIONS: The results of this study show that reduced gravity conditions lead to increased underestimation of roll self-tilt.

scholarly journals Fooling the size–weight illusion—Using augmented reality to eliminate the effect of size on perceptions of heaviness and sensorimotor prediction

2021 ◽  
Author(s):  
Nina Rohrbach ◽  
Joachim Hermsdörfer ◽  
Lisa-Marie Huber ◽  
Annika Thierfelder ◽  
Gavin Buckingham
Keyword(s):  
Augmented Reality ◽  
Visual Cues ◽  
Equal Mass ◽  
Small Object ◽  
Verbal Reports ◽  
Fully Integrated ◽  
Head Mounted Display ◽  
Lift Off ◽  
Cognitive Knowledge ◽  
Weight Illusion

AbstractAugmented reality, whereby computer-generated images are overlaid onto the physical environment, is becoming significant part of the world of education and training. Little is known, however, about how these external images are treated by the sensorimotor system of the user – are they fully integrated into the external environmental cues, or largely ignored by low-level perceptual and motor processes? Here, we examined this question in the context of the size–weight illusion (SWI). Thirty-two participants repeatedly lifted and reported the heaviness of two cubes of unequal volume but equal mass in alternation. Half of the participants saw semi-transparent equally sized holographic cubes superimposed onto the physical cubes through a head-mounted display. Fingertip force rates were measured prior to lift-off to determine how the holograms influenced sensorimotor prediction, while verbal reports of heaviness after each lift indicated how the holographic size cues influenced the SWI. As expected, participants who lifted without augmented visual cues lifted the large object at a higher rate of force than the small object on early lifts and experienced a robust SWI across all trials. In contrast, participants who lifted the (apparently equal-sized) augmented cubes used similar force rates for each object. Furthermore, they experienced no SWI during the first lifts of the objects, with a SWI developing over repeated trials. These results indicate that holographic cues initially dominate physical cues and cognitive knowledge, but are dismissed when conflicting with cues from other senses.

The role of vision on postural strategy evaluated in patients affected by congenital nystagmus as an experimental model

1999 ◽  
Vol 9 (6) ◽  
pp. 445-451
Author(s):  
S. Di Girolamo ◽  
W. Di Nardo ◽  
A. Cosenza ◽  
F. Ottaviani ◽  
A. Dickmann ◽  
...  
Keyword(s):  
Visual System ◽  
Postural Control ◽  
Visual Stimulus ◽  
Postural Balance ◽  
Visual Cues ◽  
Normal Subjects ◽  
Congenital Nystagmus ◽  
Dynamic Posturography ◽  
Normal Controls

The role of vision in postural control is crucial and is strictly related to the characteristics of the visual stimulus and to the performance of the visual system. The purpose of this investigation was to evaluate the effects of chronically reduced visual cues upon postural control in patients affected by Congenital Nystagmus (CN). These patients have developed since birth a postural strategy mainly based on vestibular and somatosensorial cues. Fifteen patients affected by CN and 15 normal controls (NC) were enrolled in the study and evaluated by means of dynamic posturography. The overall postural control in CN patients was impaired as demonstrated by the equilibrium score and by the changes of the postural strategy. This impairment was even more enhanced in CN than in NC group when somatosensorial cues were experimentally reduced. An aspecific pattern of visual impairment and a pathological composite score were also present. Our data outline that in patients affected by CN an impairment of the postural balance is present especially when the postural control relies mainly on visual cues. Moreover, a decrease in accuracy of the somatosensory cues has a proportionally greater effect on balance than it has on normal subjects.

scholarly journals Different Visual Weighting due to Fast or Slow Vestibular Deafferentation: Before and after Schwannoma Surgery

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Fredrik Tjernström ◽  
Per-Anders Fransson ◽  
Babar Kahlon ◽  
Mikael Karlberg ◽  
Sven Lindberg ◽  
...  
Keyword(s):  
Postural Control ◽  
Spatial Orientation ◽  
Visual Cues ◽  
Time Course ◽  
Vestibular Function ◽  
Sensory Systems ◽  
Vestibular Loss ◽  
Group 3 ◽  
Group 2 ◽  
Group 1

Background. Feedback postural control depends upon information from somatosensation, vision, and the vestibular system that are weighted depending on their relative importance within the central nervous system. Following loss of any sensory component, the weighting changes, e.g., when suffering a vestibular loss, the most common notion is that patients become more dependent on visual cues for maintaining postural control. Dizziness and disequilibrium are common after surgery in schwannoma patients, which could be due to interpretation of the remaining sensory systems involved in feedback-dependent postural control and spatial orientation. Objective. To compare visual dependency in spatial orientation and postural control in patients suffering from unilateral vestibular loss within different time frames. Methods. Patients scheduled for schwannoma surgery: group 1 (n=27) with no vestibular function prior to surgery (lost through years), group 2 (n=12) with remaining vestibular function at the time of surgery (fast deafferentation), and group 3 (n=18) with remaining function that was lost through gentamicin installations in the middle ear (slow deafferentation). All patients performed vibratory posturography and rod and frame investigation before surgery and 6 months after surgery. Results. Postural control improved after surgery in patients that suffered a slow deafferentation (groups 1 and 3) (p<0.001). Patients that suffered fast loss of remaining vestibular function (group 2) became less visual field dependent after surgery (p≤0.035) and were less able to maintain stability compared with group 1 (p=0.010) and group 3 (p=0.010). Conclusions. The nature and time course of vestibular deafferentation influence the weighting of remaining sensory systems in order to maintain postural control and spatial orientation.

Rehabilitation after acute vestibular disorders

2008 ◽  
Vol 123 (4) ◽  
pp. 397-402 ◽  
Author(s):  
R Teggi ◽  
D Caldirola ◽  
B Fabiano ◽  
P Recanati ◽  
M Bussi
Keyword(s):  
Visual Analogue Scale ◽  
Postural Control ◽  
Analogue Scale ◽  
Visual Cues ◽  
Control Group ◽  
Index Test ◽  
Supervised Exercise ◽  
Dynamic Gait Index ◽  
Dynamic Gait ◽  
Gait Index

AbstractObjectives:To assess the efficacy of rehabilitation for dizzy patients after recent acute vestibular disturbance.Methods:Forty patients recently hospitalised for an acute episode of rotational vertigo which lasted days were randomly divided into two groups. The first group (20 patients; group R) underwent active rehabilitation, while the second group (20 patients; group C) were told only to ‘perform their daily activities’. Group R subjects underwent a total of 10 sessions of rehabilitation, including exercises on a stabilometric platform, point de mire and a series of five exercises repeated five times daily. All patients performed static stabilometry (posturography), undertook the dynamic gait index test, and completed a dizziness handicap questionnaire and a visual analogue scale for anxiety, at baseline and on completion.Results:At 25 days, the rehabilitated patients obtained better results for all recorded outcomes, compared with the control group. The greatest difference in the rehabilitated subjects, compared with the control group, was for the dynamic gait index test; however, this difference was not statistically significant. The visual analogue scale anxiety score was statistically significantly more reduced in rehabilitated patients compared with control patients. Control patients maintained a higher visual dependence for postural control.Conclusions:These results would appear to support the effectiveness of a supervised exercise programme for patients following acute onset of vestibular disturbance. A correlation was found in both groups between dynamic gait index results and anxiety. In our experience, a rehabilitation programme seems to reduce dependence on visual cues for postural control.

scholarly journals Postural adjustment errors reveal deficits in inhibition during lateral step initiation in older adults

2013 ◽  
Vol 109 (2) ◽  
pp. 415-428 ◽  
Author(s):  
Patrick J. Sparto ◽  
Susan I. Fuhrman ◽  
Mark S. Redfern ◽  
J. Richard Jennings ◽  
Subashan Perera ◽  
...  
Keyword(s):  
Older Adults ◽  
Visual Cues ◽  
Motor Program ◽  
Postural Adjustment ◽  
Postural Adjustments ◽  
Inhibitory Function ◽  
Step Initiation ◽  
Reaction Forces ◽  
Vertical Ground Reaction Forces ◽  
Step Responses

Postural dual-task studies have demonstrated effects of various executive function components on gait and postural control in older adults. The purpose of the study was to explore the role of inhibition during lateral step initiation. Forty older adults participated (range 70–94 yr). Subjects stepped to the left or right in response to congruous and incongruous visual cues that consisted of left and right arrows appearing on left or right sides of a monitor. The timing of postural adjustments was identified by inflection points in the vertical ground reaction forces (VGRF) measured separately under each foot. Step responses could be classified into preferred and nonpreferred step behavior based on the number of postural adjustments that were made. Delays in onset of the first postural adjustment (PA1) and liftoff (LO) of the step leg during preferred steps progressively increased among the simple, choice, congruous, and incongruous tasks, indicating interference in processing the relevant visuospatial cue. Incongruous cues induced subjects to make more postural adjustments than they typically would (i.e., nonpreferred steps), representing errors in selection of the appropriate motor program. During these nonpreferred steps, the onset of the PA1 was earlier than during the preferred steps, indicating a failure to inhibit an inappropriate initial postural adjustment. The functional consequence of the additional postural adjustments was a delay in the LO compared with steps in which they did not make an error. These results suggest that deficits in inhibitory function may detrimentally affect step decision processing, by delaying voluntary step responses.

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