Peripersonal Visual-Haptic Size Estimation in Virtual Reality

2019 ◽  
Author(s):  
Nikolaos Katzakis ◽  
Lihan Chen ◽  
Fariba Mostajeran ◽  
Frank Steinicke
Keyword(s):  
Virtual Reality ◽  
Size Estimation

scholarly journals Assessing body image in anorexia nervosa using biometric self-avatars in virtual reality: Attitudinal components rather than visual body size estimation are distorted

2017 ◽  
Vol 48 (4) ◽  
pp. 642-653 ◽  
Author(s):  
S. C. Mölbert ◽  
A. Thaler ◽  
B. J. Mohler ◽  
S. Streuber ◽  
J. Romero ◽  
...  
Keyword(s):  
Body Image ◽  
Virtual Reality ◽  
Body Weight ◽  
Anorexia Nervosa ◽  
Three Dimensional ◽  
Normal Weight ◽  
Body Image Disturbance ◽  
Size Estimation ◽  
Eating Disorder Symptoms ◽  
Body Size Estimation

BackgroundBody image disturbance (BID) is a core symptom of anorexia nervosa (AN), but as yet distinctive features of BID are unknown. The present study aimed at disentangling perceptual and attitudinal components of BID in AN.MethodsWe investigated n = 24 women with AN and n = 24 controls. Based on a three-dimensional (3D) body scan, we created realistic virtual 3D bodies (avatars) for each participant that were varied through a range of ±20% of the participants’ weights. Avatars were presented in a virtual reality mirror scenario. Using different psychophysical tasks, participants identified and adjusted their actual and their desired body weight. To test for general perceptual biases in estimating body weight, a second experiment investigated perception of weight and shape matched avatars with another identity.ResultsWomen with AN and controls underestimated their weight, with a trend that women with AN underestimated more. The average desired body of controls had normal weight while the average desired weight of women with AN corresponded to extreme AN (DSM-5). Correlation analyses revealed that desired body weight, but not accuracy of weight estimation, was associated with eating disorder symptoms. In the second experiment, both groups estimated accurately while the most attractive body was similar to Experiment 1.ConclusionsOur results contradict the widespread assumption that patients with AN overestimate their body weight due to visual distortions. Rather, they illustrate that BID might be driven by distorted attitudes with regard to the desired body. Clinical interventions should aim at helping patients with AN to change their desired weight.

scholarly journals The Influence of Visual Perspective on Body Size Estimation in Immersive Virtual Reality

2019 ◽  
Author(s):  
Anne Thaler ◽  
Sergi Pujades ◽  
Jeanine K. Stefanucci ◽  
Sarah H. Creem-Regehr ◽  
Joachim Tesch ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Body Size ◽  
Visual Perspective ◽  
Immersive Virtual Reality ◽  
Size Estimation ◽  
Body Size Estimation

Körperbild bei Magersucht - Wahrnehmung ist nicht gestört

2018 ◽  
Vol 68 (02) ◽  
pp. 54-54
Keyword(s):  
Body Image ◽  
Virtual Reality ◽  
Anorexia Nervosa ◽  
Body Size ◽  
Size Estimation ◽  
Affektive Störung ◽  
Body Size Estimation

Mölbert SC et al. Assessing body image in anorexia nervosa using biometric self-avatars in virtual reality: Attitudinal components rather than visual body size estimation are distorted. Psychol Med 2017 Jul 26; 1–12 Ein gestörtes Körperbild ist ein Schlüsselsymptom bei Magersucht. Haben Magersüchtige eine verzerrte Wahrnehmung? Oder liegt hier eine affektive Störung vor? Eine Tübinger Arbeitsgruppe hat sich das Phänomen genauer angeschaut.

scholarly journals Image-based food portion size estimation using a smartphone without a fiducial marker

2018 ◽  
pp. 1-13 ◽  
Author(s):  
Yifan Yang ◽  
Wenyan Jia ◽  
Tamara Bucher ◽  
Hong Zhang ◽  
Mingui Sun
Keyword(s):  
Virtual Reality ◽  
Error Control ◽  
Imaging System ◽  
Estimation Error ◽  
Dietary Assessment ◽  
Fiducial Marker ◽  
Volume Estimation ◽  
Portion Size ◽  
Estimation Accuracy ◽  
Size Estimation

AbstractObjectiveCurrent approaches to food volume estimation require the person to carry a fiducial marker (e.g. a checkerboard card), to be placed next to the food before taking a picture. This procedure is inconvenient and post-processing of the food picture is time-consuming and sometimes inaccurate. These problems keep people from using the smartphone for self-administered dietary assessment. The current bioengineering study presents a novel smartphone-based imaging approach to table-side estimation of food volume which overcomes current limitations.DesignWe present a new method for food volume estimation without a fiducial marker. Our mathematical model indicates that, using a special picture-taking strategy, the smartphone-based imaging system can be calibrated adequately if the physical length of the smartphone and the output of the motion sensor within the device are known. We also present and test a new virtual reality method for food volume estimation using the International Food Unit™ and a training process for error control.ResultsOur pilot study, with sixty-nine participants and fifteen foods, indicates that the fiducial-marker-free approach is valid and that the training improves estimation accuracy significantly (P<0·05) for all but one food (egg, P>0·05).ConclusionsElimination of a fiducial marker and application of virtual reality, the International Food Unit™ and an automated training allowed quick food volume estimation and control of the estimation error. The estimated volume could be used to search a nutrient database and determine energy and nutrients in the diet.

Top-Down Processing and Visual Reorientation Illusions in a Virtual Reality Environment

2004 ◽  
Vol 63 (3) ◽  
pp. 143-149 ◽  
Author(s):  
Fred W. Mast ◽  
Charles M. Oman
Keyword(s):  
Virtual Reality ◽  
Visual Processing ◽  
Line Length ◽  
Perceptual Cues ◽  
Virtual Reality Environment ◽  
Top Down ◽  
Test Conditions ◽  
The Subject ◽  
Processing Mechanisms

The role of top-down processing on the horizontal-vertical line length illusion was examined by means of an ambiguous room with dual visual verticals. In one of the test conditions, the subjects were cued to one of the two verticals and were instructed to cognitively reassign the apparent vertical to the cued orientation. When they have mentally adjusted their perception, two lines in a plus sign configuration appeared and the subjects had to evaluate which line was longer. The results showed that the line length appeared longer when it was aligned with the direction of the vertical currently perceived by the subject. This study provides a demonstration that top-down processing influences lower level visual processing mechanisms. In another test condition, the subjects had all perceptual cues available and the influence was even stronger.

Laparoscopic Cholecystectomy

Swiss Surgery ◽  
2002 ◽  
Vol 8 (6) ◽  
pp. 250-254
Author(s):  
Vogelbach ◽  
Bogdan ◽  
Rosenthal ◽  
Pfefferkorn ◽  
Triponez
Keyword(s):  
Virtual Reality ◽  
Laparoscopic Cholecystectomy ◽  
Neue Technik

Fragestellung: Die dieser Untersuchung zugrunde liegende Frage war, ob das angewandte Ausbildungskonzept geeignet war, um am Beispiel der Einführung der laparoskopischen Cholezystektomie eine neue Operationsmethode in einer universitären Ausbildungsklinik mit einer grossen Anzahl Chirurgen zu etablieren. Patienten und Methodik: Seit Einführung der ersten laparoskopischen Cholezystektomie wurden alle Cholezystektomien während zwei Jahren (Mai 1990 bis Mai 1992) prospektiv erfasst. Ein Ausbildungskonzept wurde gewählt, bei dem jeweils ein Operateur durch einen Tutor geschult wurde und so 15 konsekutive Eingriffe durchführte, um dann die Technik einem weiteren auszubildenden Chirurgen zu instruieren. Resultate: In zwei Jahren wurden 355 Patienten cholezystektomiert. 60% der Operationen wurden laparoskopisch durchgeführt oder begonnen. 40% der Operationen wurden offen durchgeführt. In den ersten zwei Jahren konnten 13 Operateure (durchschnittlich 16 Operationen / Operateur , range 1 - 60) in die neue Technik eingeführt werden. Es traten keine schweren Komplikationen, insbesondere keine Gallenwegsverletzungen in dieser Einführungsphase auf. Diskussion: In der Literatur wird dieses Vorgehen bei der Einführungsphase seit 1992 wiederholt vorgestellt, diskutiert und empfohlen. Zwischenzeitlich gibt es Richtlinien von Fachgesellschaften und nationalen Institutionen, welche die Ausbildung zur Ausführung neuer chirurgischer Techniken reglementieren. In den letzten Jahren verlagern sich die ersten Ausbildungsschritte in Richtung Trainingskurse an skill-stations und virtual reality Trainer. Schlussfolgerung: Das beschriebene Ausbildungskonzept bewährte sich in der Einführungsphase der laparoskopischen Cholezystektomie zu Beginn der 90er-Jahre.

Virtual reality-enabled treatment of nightmares.

Dreaming ◽  
2018 ◽  
Vol 28 (3) ◽  
pp. 205-224 ◽  
Author(s):  
Patrick McNamara ◽  
Kendra Holt Moore ◽  
Yiannis Papelis ◽  
Saikou Diallo ◽  
Wesley J. Wildman
Keyword(s):  
Virtual Reality
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