Home | Business News | Browse by Publication | H | Human Factors

Comparing effects of 2-D and 3-D visual cues during aurally aided target acquisition.

Article Excerpt
INTRODUCTION

Recent advances in digital signal-processing technology and the development of electromagnetic position trackers have enabled the construction of virtual 3-D audio spatial displays. These displays have been used to aid visual target acquisition in many modern workstations, including aircraft cockpits and training simulators (Begault & Pittman, 1996; Bronkhorst, Veltman, & van Breda, 1996).

A number of studies have investigated the use of 3-D auditory displays to reduce the workload associated with an overloaded visual modality and to enhance the acquisition of visual targets (Bolia, D'Angelo, & McKinley, 1999: Nelson et al., 1998; Perrott, Cisneros, McKinley, & D'Angelo, 1996). For example, Perrott et al. had participants sit at the center of a geodesic sphere and detect a visual target presented at 1 of 264 different locations. Results demonstrated that the addition of a 3-D virtual spatial auditory cue produced a significant reduction in target acquisition time. Similarly, Nelson et al. demonstrated the beneficial effects of 3-D virtually localized auditory cues on performance and perceived workload in a visual target acquisition task. In that study visual targets were presented on a head-mounted display (HMD) in three auditory cue conditions that differed in the amount of information provided: localized auditory cues. nonlocalized auditory cues, or no auditory cues. Results showed that the addition of localized auditory cues led to a significant improvement in target acquisition performance and to significant reductions in workload ratings, as compared with when auditory information was either nonlocalized or absent.

Other studies have investigated possible multisensory integration effects by comparing situations in which 3-D auditory cues were presented in isolation or accompanied by a visual cue (Flanagan, McAnally, Martin, Meehan, & Oldfield, 1998: Bronkhorst et al., 1996). Bronkhorst et al. tested the effectiveness of a 3-D virtual auditory cue presented in isolation or together with a visual cue in a flight simulation experiment in which participants had to locate and track a target aircraft as quickly as possible. The results of their experiment indicated that a 3-D auditory cue could be as effective as a visual cue. A point worth mentioning is that in their study, the visual cue was a top-view radar display located away from the initial line of gaze. This implies that in order to utilize the visual cue, participants had to move their head and eyes. This may have extended the search time because participants had to look away from the search field to examine the visual cue (i.e., the radar screen).

To circumvent this potential problem, Flanagan et al. (1998) designed a 2-D exocentric visual cue in the form of an arrow always presented in the participants' line of sight. The base of the arrow was at the center of a circular visual display, whereas the head of the arrow indicated the direction in which the observer's head should be rotated in order to bring the target into view. This arrow provided information on both target azimuth and elevation. They administered a visual search paradigm in which participants were required to locate a target presented outside the initial field of view on an HMD. The target location was cued by 3-D auditory cues presented in isolation or together with the 2-D visual cue. Their results suggested that both visual and auditory spatial cues reduced search time dramatically, as compared with unaided search.

Although the visual cue designed by Flanagan et al. (1998) was in plain sight and thus easier to use than the off-center radar screen used by Bronkhorst et al. (1996), it nonetheless required a significant amount of cognitive processing. Specifically, in contrast to the auditory cues that are egocentric in nature, the information carried by the arrow needs to be extracted from an exocentric frame of reference and subsequently transformed to an egocentric reference frame that can be used to guide movements.

Thus in the Flanagan et al. (1998) study, the visual and auditory cues were based on noncomparable reference frames, with the former being exocentric and the latter egocentric. The natural question is whether this discrepancy affects target acquisition performance. Consequently the present research was designed to investigate possible differences in target acquisition performance depending on whether visual and auditory cues rely on similar or different reference frames.

EXPERIMENT 1

Experiment 1 was aimed at replicating the effects found by Flanagan et al. (1998) using a 2-D exocentric visual cue. Although this experiment was very similar to that conducted by Flanagan et al., we felt that this partial replication was necessary in order to establish a basis for comparison with Experiment 2, in which a different type of visual cue was utilized. Therefore in Experiment 1 we investigated target acquisition performance in a situation in which target location was cued by virtual 3-D auditory cues presented in isolation or accompanied by a 2-D exocentric visual cue....

View this article FREE - Now for a Limited Time, try Goliath Business News
Free for 3 Days!