Methods

There were 26 adult volunteers (19 male, 7 female). the experimental hypothesis. Three reported more than 10 minutes prior experience with virtual environments. The participants are summarized in Table 5.2.

  

Table 5.2: Participant Overview for Experiment AIIE1

Id	Gn	Prev	Id	Gn	Prev
33	M	0	46	M	0
34	F	0	47	F	0
35	M	0	48	F	0
36	M	1	49	F	0
37	M	0	50	F	0
38	M	1	51	M	0
39	M	0	52	M	0
40	M	0	53	M	0
41	M	0	54	M	0
42	M	0	55	M	0
43	M	0	56	F	0
44	M	0	57	F	0
45	M	0	58	M	1

Id is the participant number, Gn gives the gender, and Prev is ``1'' if the participant had more than 10 minutes of prior experience in virtual environments, ``0'' otherwise. Age data was not collected for this experiment, beyond noting that all participants were over 18.

See Section 3.7 for an overview of the equipment and Section 3.8.1 for a discussion of the presence questionnaire. Participants were exposed to the ``Sharkworld'' environment run on a Division ProVision 100 using a dVisor HMD. A foreground occlusion was provided with a pair of Lucas Products ``Super Sunnies'' tanning goggles with the central ultra-violet protector removed. As the tanning goggles were worn directly over the eyes and blocked peripheral vision, they removed visual cues surrounding the screen in the HMD. Thus, the tanning goggles met the ``foreground occlusion'' definition of blocking out all cues at the same or greater distance than the display.

The tanning goggles limited the FOV to about 60$^{\circ}$. A matching FOV for the non-foreground occlusion condition was provided by masking the HMD screen with construction paper affixed directly to the screen's surface.

Each participant was run for 2.5 minutes in each of the foreground occlusion and non-foreground occlusion conditions with the condition order counterbalanced across participants. They were shown how to catch moving sharks with a virtual net attached to the hand. However, their activity in the virtual environment was not constrained by any particular task. After viewing both conditions, participants completed a presence questionnaire.

Before filling out the presence questionnaire, but after exposure to the virtual environment, participants were introduced to the idea of presence with the following paragraph.

Experiencing a virtual world can lead to a conflict in where you focus your attention. For instance, in the Sharkworld, you may feel like you are in the ocean, near a shark-infested shipwreck. At the same time, you may be aware of the contradictory fact that you are just standing in the laboratory, wearing a virtul reality helmet. The following questions assess the extent to which you felt ``immersed'' in the virtual world, and the relative intensity of this feeling when wearing the tanning goggles compared to when the screen was masked with paper. There are no ``correct'' answers, please make your ratings as honestly as possible. Circle one of the numbers.

Human Interface Technology Lab