Is it possible to use highly realistic virtual reality in the elderly? A feasibility study with image-based rendering

Abstract

Background: Virtual reality (VR) opens up a vast number of possibilities in many domains of therapy. The primary objective of the present study was to evaluate the acceptability for elderly subjects of a VR experience using the image-based rendering virtual environment (IBVE) approach and secondly to test the hypothesis that visual cues using VR may enhance the generation of autobiographical memories.

Methods: Eighteen healthy volunteers (mean age 68.2 years) presenting memory complaints with a Mini-Mental State Examination score higher than 27 and no history of neuropsychiatric disease were included. Participants were asked to perform an autobiographical fluency task in four conditions. The first condition was a baseline grey screen, the second was a photograph of a well-known location in the participant's home city (FamPhoto), and the last two conditions displayed VR, ie, a familiar image-based virtual environment (FamIBVE) consisting of an image-based representation of a known landmark square in the center of the city of experimentation (Nice) and an unknown image-based virtual environment (UnknoIBVE), which was captured in a public housing neighborhood containing unrecognizable building fronts. After each of the four experimental conditions, participants filled in self-report questionnaires to assess the task acceptability (levels of emotion, motivation, security, fatigue, and familiarity). CyberSickness and Presence questionnaires were also assessed after the two VR conditions. Autobiographical memory was assessed using a verbal fluency task and quality of the recollection was assessed using the "remember/know" procedure.

Results: All subjects completed the experiment. Sense of security and fatigue were not significantly different between the conditions with and without VR. The FamPhoto condition yielded a higher emotion score than the other conditions (P<0.05). The CyberSickness questionnaire showed that participants did not experience sickness during the experiment across the VR conditions. VR stimulates autobiographical memory, as demonstrated by the increased total number of responses on the autobiographical fluency task and the increased number of conscious recollections of memories for familiar versus unknown scenes (P<0.01).

Conclusion: The study indicates that VR using the FamIBVE system is well tolerated by the elderly. VR can also stimulate recollections of autobiographical memory and convey familiarity of a given scene, which is an essential requirement for use of VR during reminiscence therapy.

Keywords: elderly; image-based rendering; immersive environment; memory; reminiscence therapy; virtual reality.

Figure 1

Four visual conditions used during the experiment and presented to participants in the following order. Notes: (A) Baseline condition (gray, a medium gray blank screen). In accordance with the classical use of pictures in reminiscence therapy, participants were presented with (B) a photograph of a well-known location in the participant’s home city in Nice (FamPhoto). The two conditions of virtual reality are presented in a random order; ie, (C) a familiar image-based virtual environment (FamIBVE) consisting of an image-based representation of a known landmark in the center of the city of experimentation (Nice), and (D) an unknown image-based virtual environment (UnknoIBVE) captured in a public housing neighborhood, containing unrecognizable building fronts. Abbreviation: IBVE, image-based virtual environment.

Figure 2

Hardware setup used for the experiments. Notes: To avoid any risk of unsteadiness or falling, each participant sat on a chair installed in front of the display screen, at a 1 meter distance. The IBVEs were captured by taking 90 photographs for each scene (FamIBVE and UnknoIBVE, respectively). In order to allow in-place navigation and interactive manipulation of objects, the photographs used for the IBVEs have a narrow field of view to provide a scale 1 immersive experience on the large screen. A small stool is placed next to the chair for the experimenter. The projectors use passive Infitec stereo via glasses, which are tracked using the ART tracking system (http://www.ar-tracking.com). In addition, we use the ART wireless finger-tracking of the orientation of the hand and the position of the fingers. We use the three-finger (thumb-index-middle finger) version. In order to increase the sensation of immersion in the virtual environment and allow participants to become familiar with finger tracking, we start the two IBVE sessions with an interactive manipulation task. This involves manipulating three-dimensional synthetic objects in the IBVEs. Specifically a plate with two dishes (one next to the other) is presented to the participant. The right dish contains three apples. The apples are dynamic rigid objects following gravity rules, controlled by a physics engine. Finally, to enrich the sensation of immersion in the virtual reality environment, we added ambient spatialized three-dimensional sound rendering (eg, street, car, and ambient noise, crowds walking and talking). Spatialized sound feedback related to the dynamic virtual objects is provided when the apples are removed or placed on the dishes. Abbreviation: IBVE, image-based virtual environment; FamIBVE, familiar image-based virtual environment; UnknoIBVE, unknown image-based virtual environment.