Assessing optimal colour and illumination to facilitate reading: an analysis of print size.

Abstract

This study examined how optimal colour/illuminationconditions and the efficacy of theiPad, LuxIQ and Smart Bulb varied as afunction of print sizein younger,older and visually impairedadults. Participants with visual impairments and simulatedlow vision (SLV) read the MNRead using the iPad, LuxIQ and SmartBulb. In the impairment condition at 1.20logMAR,the iPad (M=9.49, 95% CI [3.18, 19.42]) andLuxIQ (M=15.95, 95% CI [9.54, 24.86]) improved the readingspeeds. At 0.80logMAR (SLV), alldevices improved reading speeds of older adults(iPad (M=28.70, 95% CI [14.65, 42.51]); LuxIQ (M=49.63, 95% CI [30.04, 69.68]); Smart Bulb (M=23.11, 95%CI [3.33, 42.11])),but in younger adultsonly the LuxIQ (M=13.04, 95% CI [3.21, 21.27]) did so. In the impairmentcondition, the iPad (M=5.54,95% CI [0.31, 12.13]) and LuxIQ (M=13.90, 95% CI [7.88, 23.49])improved reading speeds. IntheSLV condition, age was a significant predictor of reading speed at 1.20logMAR(F3,164 =10.74,p<0.001,Adj. R2 =0.16). At 0.80logMAR, age andluminance, but not colour, were significant predictors(F3,164 =52.52,p< 0.001,Adj. R2 =0.49). In the impairmentcondition, both age and lux weresignificant predictors of reading speed at 1.20(F3,85 =7.14,p<0.001,Adj. R2 =0.20)and 0.80logMAR(F3,85 =7.97,p<0.001,Adj. R2 =0.22), but colour was not. Light sourceeffectiveness and optimal colour/illumination vary as a function of printsize.It appears that print size isthe most important factorfor improving reading speed. As print sizedecreases, luminance becomes crucial,and only at the smallest print sizes does the effect of colourbecome useful.