How body movement influences

Virtual Reality analgesia?

MARCIN CZUB, JOANNA PISKORZ

INSTITUTE OF PSYCHOLOGY, UNIVERSITY OF WROCLAW

VR - real time simulation of 3d environment, responding to user

actions, and immersing the user in the simulated environment.

Pict: http://en.wikipedia.org/wiki/Virtuix_Omni

https://developer.leapmotion.com/vr

http://en.wikipedia.org/wiki/Kinect

VR & Pain treatment

Analgesic efficacy of VR in the treatment of

pain:

• In oncological setting – children

• Women with breast cancer - chemotherapy

• Dentistry – reduction of pain and fear

• Experimental pain paradigms: thermal pain,

ischemic pain.

Das et al. (2005); Gershon et al., 2004; Hoffman et al., 2001

• Warm vs cold VE - hot / cold pain stimulation

• 1st person vs 3rd person – racing game

• Dynamic game vs slow paced game

• More complex VE vs less complex VE

• Active participation vs passive observation of gameplay

• Looking around and interaction vs passive observation

Comparing different VE’s and interface types:

• The relationship between VR analgesia and the strength of

one’s subjective presence in a virtual world

• Feeling and acting as if a person is located in the virtual

world

• Body movements executed in relation to a given

environment presence in that environment

Hoffman et al,2004; Slater et al,1998

• bodily engagement affective experience

• The interface that allowed for more body movement was more effective in evoking emotional reaction towards the game

Bianchi-Berthouze et al.,2007

Body movement Presence Pain alleviation

Design and methods

Independent variable:

• Type of movement (two levels) – small (mouse)and large (Kinect)

Dependent variables:

• Pain tolerance (the time participants kept their hand in cold water)

• Pain intensity (Visual Analogue Scale)

• Presence (Igroup Presence Questionnaire)

Within participants experimental design

• Without no-VR control condition

Cold Pressor Test

• temperature 0.5-1.5 °C

• water circulator, a separate ice container, and a

digital thermometer

VAS

• a horizontal 10cm continuous line - strength of experienced

pain, expressed on the scale in centimeters, where 0

represented no pain, and 10 extreme pain

• commonly used in CPT, validity similar to other measures

Igroup Presence Questionnaire

Schubert, 2003

• Spatial presence – the sense of being located inside a VE

• Involvement – the level of engagement in a VE

• Realism – the sense of VE realism

• General – an additional item measuring the general “sense of

being there”

• Custom made game

• Steering white sphere, collecting yellow spheres, avoiding collision with red spheres

Game

Equipment

• HMD’s - E-Magin Z-800, SVGA resolution, 40 deg diagonal

FOV (which equals looking at a 2.7m diagonal movie screen

from 3.7 m distance).

• Kinect/mouse - require only the use of a dominant limb

• both are common computer peripherals

Participants

• 30 volunteers, students of Wroclaw universities

• 20 females (average age: 20,55; SD = 1,50; min = 19,

max = 24) and 10 males (average age: 25,60; SD = 9,

26 ; min = 18 ; max = 50)

• Recruited through University’s social media pages

Procedure

• Practice session – Kinect – until 10

points

• 2 conditions, counterbalanced

order

• 4 minutes – maximum time in cold

water

• a 15 minute break between

conditions in order to warm up the

hand

Results

• N = 26; T = 86.5, Z = 2.26, p = 0.024

• On average, in high motion condition participants kept their hand in a

cold water for 25 seconds more.

• Effect size: r = 0.44

N = 22, T = 104, Z = 0.73, p = 0.47

• VAS after removing the goggles attention no

longer distracted by the game

• Focus on the pain experience in order to assess its intensity

• VAS should be implemented into the VR application itself

Negative correlation between pain tolerance and pain intensity Large movement: r = -0.38, p < 0.05 Small movement: r = - 0.42, p < 0.05

• Pain experienced during a cold pressor test increases slowly with time

• But it can be assumed, that participants who kept their hand in cold water longer did so because they felt less pain

Two possible, conflicting predictions could be made about

the pain tolerance/pain intensity relationship:

IPQ results

• No significant correlations between IPQ dimensions and

the pain measures used in the study

• IPQ results did not differ between conditions:

• Spatial presence: t= -1.96; p = 0.059

• Involvement: t = - 1. 21; p = 0.24

• Realism: t = - 0.37, p = 0.72

• General: t = 0.53; p = 0.60)

Other results:

• Kinect steering as significantly more difficult than mouse

steering (t = 8.70; p < 0.0001)

• Significantly more points while steering with the computer

mouse, comparing to Kinect. (t = 4.169; p = 0.0003)

Methodological improvements:

• Precise measurement of the amount of movement

• Implementing VAS inside the VE

• Using behavioural or physiological presence measures

• Better control over difficulty and novelty of interfaces

• Collecting physiological data – heart rate, blood pressure, respiration rate

Questions:

• How important are visual consequences of movement?

• Complexity of movement, number of body parts engaged

• Other experimental pain paradigms – e.g. ischemic pain

• Clinical populations – with various movement restrictions

Thank you