Abstract
Purpose :
Hands-free phone calls while driving are common but can increase response time and error rate for detection of low contrast targets.1 Automobile displays require shifts in fixation particularly during navigation. Our purpose was to determine if a display simulating a navigation task impairs response time and sensitivity to low contrast color & luminance targets.
Methods :
A computer-based program (Innova Systems, Inc.) on a Microsoft Surface display (17x11 deg., 3 feet viewing distance) was used to measure color (L, M & S cone) contrast sensitivity (CS) and black-white luminance CS (20/200) and low contrast (6%) visual acuity (VA). Each subject was tested with and without visual distraction from an iPad mini display (13x8 deg.) immediately to the right of the main CS display. During distraction an auditory cue “look” occurred every 10 sec. and the subject was required to look at the iPad to verbally identify a figure in one of four quadrants of a simulated intersection. Subjects were tested with and without distraction in randomized order. Repeated measures ANOVA and paired t-tests assessed effects of distraction.
Results :
24 visually normal subjects (mean age ± SD = 27 ± 5 YO, 14 females, 10 males) participated after providing written informed consent in accord with our IRB approved protocol. Mean CS and VA were slightly higher without distraction, but t-tests indicated that this was limited to L cone CS (P < .02). Response time after visual distraction was significantly increased with no significant difference between color and luminance tests (F = 50.53, P < .0001). Mean [SE] response time with distraction (1.80 [.07] sec.) was higher than without distraction (1.56 [.06] sec.; mean increase with distraction: 0.24 [.06] sec., 95% confidence interval: 0.12 to 0.36 sec., P < .0001).
Conclusions :
These results, wherein response time was significantly delayed by visual distraction, are comparable to those for verbal distraction during hands-free phone calls.1 If a vehicle is traveling 65 miles/hour (95.33 feet/sec.), then a visual distraction lasting 0.24 sec. would diminish direct visibility for 22.88 feet (1.6 car lengths), large enough to render low contrast targets undetectable, posing a formidable threat to safety.
1Rabin JC. et al., Am Journal of Preventive Medicine, Volume 51, Issue 4, e117 - e118
This is a 2020 ARVO Annual Meeting abstract.