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Perspectives on Designing Human Interfaces for Automated Systems
Published in Richard L. Shell, Ernest L. Hall, Handbook of Industrial Automation, 2000
Anil Mital, Arunkumar Pennathur
where H is the height of the stimulus detail, and D is the distance from the eye, both H and D measured in the same units of distance. Besides minimum separable visual acuity, there are other types of visual acuity measure, such as vernier acuity (ability to differentiate lateral displacements), minimum perceptible acuity (ability to detect a spot from its background), and stereoscopic acuity (ability to differentiate depth in a single object). In general, an individual is considered to have normal visual acuity if he or she is able to resolve a separation between two signs 1′ of arc wide. Visual acuity has been found to increase with increasing levels of illumination. Luckiesh and Moss [73] showed that increasing the illumination level from approximately 101× to 1001× increased the visual acuity from 100 to 130%, and increasing the illumination level from approximately 101× to 10001× increased the visual acuity from 100 to 170%. For provision of maximum visual acuity, it is recommended that the illumination level in the work area be 10001×. Providing adequate contrast between the object being viewed and the immediate background, and making the signs and characters (in the object being viewed) sharp, will also increase visual acuity. The general recommendation is to use dark symbols and characters on a bright background than vice versa, as the former increases the visual acuity. Visual acuity has also been shown to decrease with age [74]. Figure 10 illustrates how visual acuity decreases with age.
Spatialized Vibrotactile Feedback Improves Goal-Directed Movements in Cluttered Virtual Environments
Published in International Journal of Human–Computer Interaction, 2018
Céphise Louison, Fabien Ferlay, Daniel R. Mestre
Subjects were naïve as concerns the purpose of the experiment. All subjects reported normal vision and sense of touch and were free from any locomotor or postural disorder. Their stereoscopic acuity was tested using the Randot® Graded Circles test (Stereo Optical Company Inc, Chicago, IL, USA). Their inter-pupillary distance (IPD) was measured using the Oculus configuration utility software. IPD ranged from 60.6 to 67.9mm (mean = 64.1; SD = 2.2), and was used to adjust stereoscopic rendering to each individual. The subjects were not selected regarding their stature. Their standing height ranged from 163 to 190 cm (mean = 177.6; SD = 7.1).