evaluation of tablet-based methods for assessment of
TRANSCRIPT
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2/1/2020 HVEI - Jan 2020
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Evaluation of Tablet-Based Methods for Assessment of Contrast Sensitivity
on Mobile Touch-Screens
Jeffrey B. Mulligan
NASA Ames Research Center
Human Vision and Electronic Imaging - January 2020
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1/23/2020 Motivation: SANS
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Motivation: SANS
From https://humanresearchroadmap.nasa.gov/Risks/risk.aspx?i=105
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1/23/2020 Orthostatic pressure and gravity
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Orthostatic pressure and gravity
Figure from wikipedia page "Space Medicine," attributed to NASA.
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1/23/2020 Effects on the eye
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Effects on the eye
Figure from Marshall-Bowman, K., Barratt, M. R., and Gibson, C. R. (2013). "Ophthalmic changes and increased intracranial pressureassociated with long duration spaceflight: An emerging understanding." Acta Astronautica, v. 87, pp. 77-87.
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1/23/2020 Effects on the eye
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Effects on the eye
Figure from Marshall-Bowman, K., Barratt, M. R., and Gibson, C. R. (2013). "Ophthalmic changes and increased intracranial pressureassociated with long duration spaceflight: An emerging understanding." Acta Astronautica, v. 87, pp. 77-87.
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1/23/2020 Goals
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Rapid vision assessment for daily use
Simple hardware with low up-mass
Approach: contrast sensitivity on Apple iPad
Goals
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1/23/2020 What is Contrast Sensitivity?
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What is Constrast Sensitivity?
From http://www.telescope-optics.net/aberrations_extended.htm
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1/23/2020 The double-sweep grating
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The double-sweep grating
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1/23/2020 Early public appearances
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Described for use in optical testing(Washer & Rosberry, 1951)
Shown at 1964 OSA meeting(Robson & Campbell)
Appeared in "Mach Bands"
by F. Ratliff (1965)
Appeared in "Visual Perception"
by T. N. Cornsweet (1970)
IOVS cover image, 1978-1982
Early public appearances
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1/23/2020 Jeff's idea for a rapid test
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Display sweep grating on touch screen
Use finger to indicate edge of visibility
Advantages: portable, fast (1-2 seconds for entire curve)
Problems: unknown criterion, motor noise, cheating, reduction of phase uncertainty
Mulligan, J. B. (2016). "A method for rapid measurement ofcontrast sensitivity on mobile touch-screens." Proc. HVEI.
Jeff's idea for a rapid test
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1/23/2020 Repeatability
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Repeatability
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1/23/2020 The present study: validate against other methods
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Traditional quick-and-dirty: method of adjustment
The gold standard: 2AFC
Gabor patch stimuli
The present study: validate against othermethods
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2/1/2020 Method of adjustment
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Variable-contrast static Gabor patch
Subject swipes up or down to increase or decrease contrast
Adaptive contrast increment/decrement
Effectively a yes/no experiment with 50 trials
DEMO
Method of adjustment
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2/1/2020 Adjustment data psychometric function
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Adjustment data psychometric function
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2/1/2020 Parabolic fit to adjustment thresholds
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Parabolic fit to adjustment thresholds
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2/1/2020 Two-alternative forced choice (2AFC)
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Gabor patch pulsed with a Gaussian temporal contrast window
Two temporal intervals indicated by audio tones
Stimulus presented in one of the two intervals
Subject indicates stimulus interval with response buttons
2-to-1 staircase with adaptive step size
DEMO
Two-alternative forced choice (2AFC)
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2/1/2020 Staircase raw data
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Staircase raw data
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2/1/2020 2AFC data psychometric function
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2AFC data psychometric function
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2/1/2020 Parabolic fit to 2AFC thresholds
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Parabolic fit to 2AFC thresholds
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2/1/2020 The updated swipe method
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15 slightly different images presented
Subject is shown swipe, can accept or redo
DEMO
The updated swipe method
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2/1/2020 Parabolic fit to swipes
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Parabolic fit to swipes
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2/1/2020 Comparing the methods
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Comparing the methods
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2/1/2020 Comparing the methods
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Comparing the methods
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2/1/2020 Comparing the methods
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Comparing the methods
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2/1/2020 Comparing the methods
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Comparing the methods
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2/1/2020 Comparing the methods
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Comparing the methods
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2/1/2020 Comparing the methods
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Comparing the methods
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2/1/2020 Comparing the methods
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Comparing the methods
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2/1/2020 Comparing the methods
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Comparing the methods
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2/1/2020 Summary
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2AFC estimates greater sensitivity than adjustment
Swipe method estimates more sensitivity still?
SF differences may be explained by temporal factors
Swipe method variability comparable to 2AFC
Caveat: more efficient 2AFC methods availablee.g. QuickCSF, Lesmes et al.
Summary
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2/1/2020 Conclusions
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The swipe method is a viable choice for CSF estimation
Accuracy probably sufficient for longitudinal monitoring
Gamification?
THANKS FOR LISTENING!
Conclusions