When performing visually demanding tasks such as reading on a smartphone, users can incur excessive ocular stress because of small image size. Such stress is likely exacerbated by lower display resolution, improper ambient lighting, and less ideal subpixel arrangement that further degrade image appearance. Senior users (40 years and older) should be more affected by these factors because of their degraded accommodation ability. The present study evaluated effects of these smartphone properties on visual performance, discomfort, and preference of young and senior adult viewers.
To this end, young (age 18 to 30) and senior (age 40 to 65) adults performed visual discrimination and reading tasks on three phones with vertical strip LCD, PenTile OLED, and vertical strip OLED displays that differed on resolution and subpixel structures. Their viewing distance and visual performance were measured in visual discrimination task, and also perceived discomfort in reading task. Subjective comparisons of display properties for the tested phones were also conducted with text, photo, and video images.
Our findings revealed that LCD resulted in better discrimination of Landolt C orientation (with fixed target distance) and enabled longer viewing distances in the reading task compared to OLEDs. OLED displays were better in displaying red and blue text, whereas LCD was better in displaying black&white and green text. Senior viewers performed more poorly on the Landolt Ring task with fixed viewing distance, but less so with LCD display and self-adjusted distance. Viewing symptoms were mostly greater with higher illumination, and not affected by tested phones alone. Young viewers preferred LCD displays to OLEDs, but seniors showed no preference.
The present findings suggest that screens with higher resolution and better subpixel structure afford farther viewing distance and better visual discrimination, allowing senior viewers to match the performance of younger viewers. These indicate the importance of smartphone display quality, especially for senior viewers and those with poorer visual abilities. avoiding excessive ambient light is also important for attenuating visual comfort.
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