Interacting with virtual objects via embodied avatar hands reduces pain intensity and diverts attention

Abstract

The current study introduces a new paradigm for exploring cognitive factors in pain. Interacting with virtual objects via embodied avatar hands increased the illusion of "being there" in the virtual world, increased VR analgesia for acute pain, and reduced accuracy on an attention demanding task. Twenty-four healthy volunteer college students participated in this within-subject randomized crossover design study. During Phase 1, each participant received brief thermal pain stimuli during interactive embodied avatar VR vs. passive VR (no avatar and no interactivity), VR treatment order randomized. After each pain stimulus, participants provided subjective 0-10 ratings of pain. Compared to the passive VR condition, during the interactive avatar VR, participants reported significant reductions in (1) worst pain, (2) pain unpleasantness, (3) time thinking about pain and (4). they had significantly more fun during the pain stimulus (p = .000 for each). During Phase 2, participants performed a divided attention task in each of the two VR conditions. Participants made significantly more errors on the divided attention task during the interactive avatar VR condition, compared to passive VR, implicating an attention mechanism for how virtual reality reduces pain and helping understand how VR influences pain perception.Trial registration: NCT04245475. Date of registration: 29/01/2020.

Figure 1

Increasing the illusion of “being there” in VR may increase the amount of attention drawn into VR, leaving less attention available to process incoming nociceptive signals. If so, participants may feel less pain during Avatar VR. Copyright Hunter Hoffman, www.vrpain.com.

Figure 2

Participants’ enrollment flowchart.

Figure 3

A detailed description of the stimulus sequence. Participants are randomly assigned to either Treatment Order 1 or Treatment Order 2.

Figure 4

While wearing the XTAL VR helmet, any movements of the hands or fingers in the real world are seen by the participant in the virtual world (the image on the right is from the Architecture World demo by VRgineering.com). Photo and image copyrights Hunter Hoffman, U.W., vrpain.com.

Figure 5

Phase 1. Compared to a passive VR version of the same world, interactive avatar VR was significantly more effective at reducing pain intensity (worst pain ratings).

Figure 6

Boxplot showing lower quartile, median, upper quartile, and outliers for Phase 1 results. Interactive avatar VR was significantly more effective at increasing the illusion of “being there” in the virtual world.

Figure 7

Compared to passive VR, interactive avatar VR significantly reduced participants’ accuracy on an attention demanding task.

Figure 8

Phase 1. On an n = 12 side study to test important assumptions of my thermal pain paradigm, consistent with my assumptions, as predicted, no significant differences were found between No VR, passive VR on Test 1 vs. passive VR again on Test 2 reducing pain intensity (worst pain ratings).