Resolution of screens (pixels), physical screen sizes (cm), pixels per cm and viewing distance (cm) required to permit testing 1.0 min of visual angle subtended per pixel (cm) for the 3 tablets tested.

<p>Resolution of screens (pixels), physical screen sizes (cm), pixels per cm and viewing distance (cm) required to permit testing 1.0 min of visual angle subtended per pixel (cm) for the 3 tablets tested.</p

Available contrasts on the 3 tablet computers for black letters (Weber Contrast, left) and gratings (Michelson Contrast, right).

<p>Where contrast resolution meant that fewer than 5 luminance steps were available to draw the grating on the tablet computer, the symbols are shown in black. The grey band represents normal ranges for the Vistech and Pelli-Robson charts.</p

Setup for measurement of effect of reflections on displayed contrast.

<p>The light source was initially placed directly above tablet (condition a) and then moved to 45° from screen (condition b). The photospectroradiometer was placed directly in front of the display for measurement of luminance. In condition (c) the light source was placed directly above the tablet screen which was then rotated to 45° with respect to the photospectroradiometer.</p

Errors in luminance (cd/m²) and contrast at different locations on the tablet screens measured if an observer were viewing all peripheral targets from a central location.

<p>Centre square shows target luminance (top value), background luminance (middle value) and contrast (bottom value) for the iPad (red values), Nexus 10 (green values) and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0095074#pone-0095074-t002" target="_blank">Tab 2</a> 10.1 (blue values). Peripheral squares display the percentage change in these values compared to the centre for each of the three tablets.</p

Box plots showing % change in luminance in the target when measured against 8 different backgrounds.

<p>Note that the mean change for the iPad and Nexus 10 are close to zero while mean change for the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0095074#pone-0095074-t002" target="_blank">Tab 2</a> 10.1 is −5%.</p

Warm up time (minutes) required for luminance to stabilize on screen after 3 different “off” periods.

<p>Warm up time (minutes) required for luminance to stabilize on screen after 3 different “off” periods.</p

Change in luminance (L) (%) and contrast (C) (%) under the three different conditions shown in figure 5 for the three devices.

<p>Major changes in contrast and luminance occurred only under condition C.</p

Phase data.

<p>Averaged phase values (left plots) for L- (red circles) and M- cone (green triangles) driven ERG responses as a function of stimuli configuration at 5 different temporal frequencies. The right plots correspond to the averaged L-M phase difference estimated from phase responses at each temporal frequency.</p

Amplitudes as a function of stimulus diameter.

<p>Linear regression analysis between the logarithm of amplitude and the logarithm of stimulus diameter for L-cone (red circles) and M-cone (green triangles) driven ERGs at 5 different temporal frequencies. The regression coefficient (R²) and the linear regressions are showed for each regression.</p

Original ERG traces.

<p>Original ERG traces for L- (10% cone contrast, dark red traces) and M- cone (10% cone contrast, green dashed traces) isolating stimuli, measured in one subject. The responses from two temporal frequencies (500 ms excerpts at 12 Hz and 200 ms excerpts at 36 Hz) and five different spatial configurations (20°, 50°, FF, AN10°, AN50°) are shown.</p