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Table 1 Summary of task design, manipulations, results and implications for the Local Features papers included in the review

From: How can basic research on spatial cognition enhance the visual accessibility of architecture for people with low vision?

Local features
Citation Low vision type Task paradigm Main manipulations Results Implications for design
Bochsler et al. (2012) Blur: 2 severity levels
Mild: P–R = 0.8
logMAR = 0.88
Severe: P–R = 0.6
logMAR = 1.65
Viewed and identified steps up or down, ramps up or down, or flat surfaces Distance: 1.52, 3.05, and 6.10 m
Blur severity
Locomotion versus static viewing
High-contrast checkerboard texture versus uniform gray surface
1. Poorer performance with textured compared to uniform surface with severe blur
2. Locomotion improved accuracy over static viewing
Avoid high contrast texture on ground surfaces
Designing for active locomotion could facilitate feature recognition
Bochsler et al. (2013) LV individuals (variety of types)
Acuity range from logMAR 0.98 to 2.18 (20/191–20/3000)
Field loss range of peripheral, central, or both
Viewed and identified steps up or down, ramps up or down, or flat surfaces Distance: 1.52, 3.05, and 6.10 m
Lighting: near and far
Target-background contrast
Locomotion versus static viewing
1. People with LV outperformed those with simulated LV and were not strongly affected by target-background contrast
2. Similar to simulated LV, people with LV showed better identification for step-up compared to step-down and benefited from closer distances and locomotion
Designing for active locomotion could facilitate feature recognition
Kallie et al. (2012) Blur (severe)
P–R = 0.6
Snellen 20/900
Viewed boxes and cylinders (2–6 ft)
Detection, confidence for detection, shape, and height
Distance: 3.05, 5.18, 7.32 m
Lighting: overhead or window
Color: White, gray
Object height: short, medium, tall
Shape: box, cylinder
1. Cylinders were easier to identify compared to boxes
2. Advantage for color (white vs gray) depended on the lighting
3. Better performance resulted with larger and closer objects
Consider potential interactions of color, object shape, and lighting
Overhead and window lighting may not differentially affect performance
Legge et al. (2010) Blur: 2 severity levels
Mild: P–R = 0.8
logMAR = 0.81–.85
Severe: P–R = 0.6
logMAR = 1.64–1.67
Viewed and identified steps up or down, ramps up or down, or flat surfaces
Uniform gray surface with varying backgrounds
Distance: 1.52, 3.05, and 6.10 m
Lighting: overhead, near window, far window
Blur severity
Background color: black or gray
1. Steps up were more visible than steps down
2. Local geometric cues for identification (e.g., shape of edge contours of a walkway in an image) were dependent on viewing distance and contrast
3. A cue for identifying a ramp was its elevation in the image
Visibility of steps down is of particular concern and may be enhanced by contrast between riser and contiguous surface, and directional lighting
Rand et al. (2011) Blur (severe) logMAR = 1.60 (20/791) Distance perception to targets Visual horizon height (wall-floor boundary): actual or raised
Distance: 3, 4.5, 6 m
1. When the “horizon” was raised, the angle of declination to the target increased, and viewers judged the distance to targets on the ground to be closer Create high contrast between wall and floor to make the visual horizon salient
Rand et al. (2012) Blur (severe)
P–R = 0.46
logMAR = 1.51 (20/647)
Distance and size perception of targets on stands Distance: 1.5, 2.7, 4 m
Color of stands that the targets were placed on–created high or low contrast with ground plane
Blur versus normal vision
1. Distance and size judgments were accurate to the targets presented on the visible black stands
2. When the stands were not visible (painted gray and viewed through blur goggles), participants overestimated size and distance to the target
Increase visibility of information for grounding targets when they are located above the ground surface
Tarampi et al. (2010) Blur (severe)
P–R = 0.36
logMAR = 1.53
Distance perception by blind walking to targets Distance: 1.5, 3.1, 6 m
Blur versus normal vision
1. Relatively accurate distance perception with blur, although with increased variability Accuracy in distance estimation may be increased with salient visual horizon cues
  1. P–R Pelli–Robson contrast sensitivity value, LV low vision, Blur simulated reduced acuity and contrast sensitivity, Snellen values are in parentheses