Effects of Sensory Information and Prior Experience on Direct Subjective Ratings of Presence

We report three experiments using a new form of direct subjective presence evaluation that was developed from the method of continuous assessment used to assess television picture quality. Observers were required to provide a continuous rating of their sense of presence using a handheld slider. The first experiment investigated the effects of manipulating stereoscopic and motion parallax cues within video sequences presented on a 20 in. stereoscopic CRT display. The results showed that the presentation of both stereoscopic and motion parallax cues was associated with higher presence ratings. One possible interpretation of Experiment 1 is that CRT displays that contain the spatial cues of stereoscopic disparity and motion parallax are more interesting or engaging. To test this, observers in Experiment 2 rated the same stimuli first for interest and then for presence. The results showed that variations in interest did not predict the presence ratings obtained in Experiment 1. However, the subsequent ratings of presence differed significantly from those obtained in Experiment 1, suggesting that prior experience with interest ratings affected subsequent judgments of presence. To test this, Experiment 3 investigated the effects of prior experience on presence ratings. Three groups of observers rated a training sequence for interest, presence, and 3-Dness before rating the same stimuli as used for Experiments 1 and 2 for presence. The results demonstrated that prior ratings sensitize observers to different features of a display resulting in different presence ratings. The implications of these results for presence evaluation are discussed, and a combination of more-refined subjective measures and a battery of objective measures is recommended

CountMeIn: Evaluating Social Presence in a Collaborative Pervasive Mobile Game Using NFC and Touchscreen Interaction

This paper presents the motivation, design and evaluation of CountMeIn, a mobile collaborative pervasive memory game to revive social interactions in public places (e.g. a train station or bus stop). Two versions of CountMeIn were tested; an NFC-based and a touchscreen version. In a 2×1 within-subject (NFC vs. Touch) experiment (N = 20), postexperiment group interviews and findings indicate the NFC version led to increased perception of social presence while participants were more aware of others' actions and intentions (mode of co-presence). However, we did not find quantitative evidence that attributes of social presence were higher from the Social Presence Game Questionnaire. Together, our findings suggest that placement of a physical NFC interface does not necessarily increase perceived social presence when users play collaboratively. However, social expansion in mobile collaborative pervasive games can greatly benefit from people's mutual awareness from such an interface. This mutual awareness has the potential to both attract users and spectators, and reduce anxiety of users to invite spectators, or accept an invite from users

Multi-user 3D display

A 3D display that incorporates an RGB laser projector as the backlight for an LCD and a head position tracker is described. The display provides 3D to several viewers who do not need to wear special glasses and are able to move freely over a large region. It operates on the principle of forming regions in the viewing field, referred to as exit pupils, where either a left image or a right image is seen on the screen. These exit pupils follow the positions of the viewers' eyes by using the output of the head tracker to control the backlight optics. The stereo image pair is displayed on a direct-view LCD and a steering optics array behind this forms the pupils. Frame sequential operation is being investigated as this enables higher resolution and simplified optics. An RBG laser source illuminates a binary phase hologram on an LCOS device that directs light to the appropriate positions on the array. The information on this device is derived from a high-precision single-user 3D video head tracker that employs an appearance-based method for initial head detection and a modified adaptive block-matching technique for head and eye location measurements in the tracking phase