Augmented reality (AR) displays often reduce the visual capabilities of the user. This reduction can be measured both objectively and through user studies. We acquired objective measurements with a color meter and conducted two user studies for each of two key measurements. First was the combined effect of resolution and display contrast, which equate to the visual acuity and apparent brightness. The combined effect may be captured by the contrast sensitivity function and measured through analogs of optometric exams. We expanded the number of commercial devices tested in previous studies, including higher resolution and video-overlay AR displays. We found patterns of reduced contrast sensitivity similar to previous work; however, we saw that all displays enabled users to achieve the maximum possible acuity with at least moderate levels of contrast. The second measurement was the perception of color. Objective measurements showed a distortion of color, notably in the blue region of color space. We devised a color matching task to quantify the distortion of color perception, finding that the displays themselves were poor at showing colors in the blue region of color space and that the perceptual distortion of such colors was even greater than the objective distortion. We noted significantly different distortions and variability between displays.

Head-worn displays have been an integral part of augmented reality since the inception of the field. However, due to numerous difficulties with designing using such unique hardware, the perceptual capabilities of users suffer when looking at either the virtual or real portions of the augmented reality. We discuss the perceptual background and a series of experiments-in the literature and in our laboratoriesmeasuring the degradation of basic functions of the human visual system when using head-worn augmented reality displays. In particular, we look at loss of visual acuity and contrast (and how these in turn affect text legibility), distortion of perceived colors, and difficulties of fusing stereo imagery. We discuss the findings and the implications for head-worn display design.

When designing spatial information displays and warning systems, particularly those with an auditory component, designers should ensure that either verbal-directional or nonverbal-spatial information is utilized by all alerts to reduce interference.

Summary:A spatial auditory Stroop paradigm was used to examine the effects of verbal-spatial cue conflict on response accuracy, reaction time, and driving performance. Participants responded to either the semantic meaning or the spatial location of a directional word, which were either congruent (i.e. the word "right" being presented from the right) or incongruent (i.e. the word "right" being presented from the left), while following a lead car in a simulated driving scenario. Accuracy was worse when participants were responding to the spatial location of a word in an incongruent trial, indicating that participants experienced significant interference when trying to ignore the semantic meaning of the word when it conflicted with the presentation location. Implications for the design of collision-avoidance warning systems are discussed.

An auditory spatial Stroop paradigm was used to examine the effects of semantic and spatial audio cue conflict on accuracy and response time. Participants responded to either the semantic meaning or the spatial location of a directional word, which was either congruent (i.e. the word “right” being presented from the right) or incongruent (i.e. the word “right” being presented from the left). Navigational strategy was also assessed to determine if individual differences on this measure could affect responses to semantic or location information. An interaction between task type and navigational strategy indicated that people who preferred a verbal strategy responded faster to semantic content and people who preferred a spatial strategy responded faster to location information. Implications of these results are discussed in terms of the design of collision avoidance systems.