A study of Active Navigation and Object Recognition in Virtual Environments

We investigated the importance and efficiency of active and passive exploration on the recognition of objects in a variety of virtual environments (VEs). In this study, 54 participants (19 males and 35 females) were randomly allocated into one of two navigation conditions (active and passive navigation). The 3D visual display was presented through HMD and participants used keyboard to navigate VEs in active navigation condition. The VEs consisted of exploring four rooms (library, office, lounge, and conference room), each of which had 15 objects. ‘Active navigation’ was performed by allowing participants to self-pace and control their own navigation within a predetermined time limitation for each room. ‘Passive navigation’ was conducted by forced navigation of the four rooms in random order. Total navigation duration and objects for both navigations were identical. After navigating VEs, participants were asked to recognize the objects that had been in the four rooms. Recognition for objects was measured by response time and the percentage of hit, miss, correct rejection, and false alarm responses. Those in the active navigation condition had a significantly higher percentage of hit responses (t (52) = 4.000 p < 0.01), and a significantly lower percentage of miss responses (t (52) = –3.763, p < 0.01) in object recognition than those in the passive condition. These results suggest that active navigation plays an important role in spatial cognition as well as providing a better explanation about the efficiency of learning in a 3D-based program. ANNUAL REVIEW OF CYBERTHERAPY AND TELEMEDICINE 68 ample, a study of hundreds of city inhabitants using different types of navigation in an urban area found that car passengers learned less than automobile drivers about the layout of a town route (Appleyard, 1970). There was also a small but significant advantage in wayfinding ability following active navigation of a VE compared with a condition in which participants passively watched a prerecorded route through the environment (Peruch, Vercher, & Gauthier, 1995). These results imply that active navigation plays an important role in determining how vision is used to assist spatial knowledge and learning. However, not all studies have shown superiority of activity over passivity (Ito & Matsunaga, 1990; Gaunet, Vidal, Kemeny, & Berthoz, 2001). There has been a failure to find a beneficial effect of active exploration on orientation in VEs. Moreover, a recent study compared experimental conditions which were active, passive, and snapshot, in directing exploration using a driving simulator (Gaunet et al., 2001). The active and passive exploration conditions led to similar performances for path memory but the snapshot exploration condition resulted in lower performance. There were no differences in performance between the active and passive exploration, although continuous visual stimulation was essential for the acquisition of spatial abilities. These inconsistent results suggest that factors such as the amount of attention directed to the task and the kinds of information available may influence the active-passive navigation (Flach, 1990). In other words, these studies have failed to show a superiority of active navigation in VEs; the driving simulator environment was limited in its ability to test exact spatial abilities and the amount of attention in active and passive conditions were not identical (e.g., only the participants in the active navigation condition were limited to the visual and tactile simulated apparatus). In the present study, therefore, we examine the role of active navigation in the efficient acquisition of spatial knowledge, and further investigate the relative effectiveness of active navigation and passive navigation by controlling for the previously mentioned limitations. MATERIALS AND METHODS Participants Participants were 54 adults in the range of 19– 29 years of age (M = 22.72, SD = 2.5) who were recruited at K University in Korea. Nineteen (35.2%) were males and 37 (64.8%) were females; mean ages were 24 years (SD = 2.13) and 22 years (SD = 2.45) respectively. All participants gave written consent. Instruments and measures The virtual environments were created using the Direct X, Pentium IV PC, with an Open CL Accelerator VGA card. The 3D visual display was presented through an Olympus FMD-250W Head Mounted Display (HMD) with resolution of 800 x 600 pixels. The virtual environments consisted of four rooms (library, office, lounge, and conference room). Participants were required to complete a demographic form and a Simulator Sickness Questionnaire (Kennedy, Lane, Berbaum, & Lillienthal, 1993) designed to measure the incidence of simulator sickness symptoms in a variety of task performance environments. Procedure Before the experiment, participants were asked to complete and return their demographic questionnaire. Participants were randomly divided into one of two VE navigation conditions; 22 were in the active navigation group and 32 were in the passive navigation group. The VE consisted of four rooms (library, office, lounge, and conference room), and each room had 15 objects (total of 60 objects). The rooms were identical in size. The participants in the active navigation group were shown how to move around the virtual environment using the HMD and keyboard and asked to explore at their own pace within the predetermined time limitation for each room. Participants in the passive navigation group passively explored the four rooms in random order. During the passive navigation, each target object was presented for 2000 ms without motion, and the Inter-Stimulus Interval (ISI) between objects was 5000 ms. The total duration of navigation was limited to 125 s and objects presented in both conditions were identical. After navigation, all participants were asked to complete the recognition task with 60 old items, which had previously been shown during the navigation, and 60 new items, which had not been presented before. The familiarity, emotional valence and arousal dominance items were matched on two categories (old and new objects) in a previous survey. Before the recognition task, participants were instructed to com-