Table 1 Hard- and software settings to consider to achieve comparable results to CRT monitors with LCD monitors.

LCD panel type

IPS (in-plane switching): true-color and contrast less dependent on viewing angle, slower response time;

TN (twisted nematic): fast response time, colors fade with non-optimal viewing angle.

Whenever timing is an issue: Use TN panels

In the present study, TN panels were used.

Native resolution, screen diagonal, and aspect ratio

With constant screen diagonal and aspect ratio: The higher the resolution, the smaller objects and stimuli that are measured in pixels appear on the screen.

To achieve results as close as possible to a CRT experiment, calculate the size (e.g., in mm) of one native pixel and resize the stimuli if necessary, so that the real size (in mm) on the CRT corresponds to the real size on the LCD.

Take the aspect ratio into account to avoid distortions like they would appear when a resolution with an aspect ratio of 4:3 (e.g., 1024 * 768) is applied to a monitor with a native aspect ratio of 16:9 (e.g., native resolution of 1920 * 1080). If you need to do the latter, consider letterboxing.

In the present study, CRT resolution was 1024 * 768 (visible area 324 * 243 mm, aspect ratio 4:3), diagonal 17”, dimensions of 1 pixel: 0.316 * 0.316 mm. LCD resolution was 1024 * 768 (visible area 531 * 299 mm, aspect ratio 16:9, dimensions of 1 pixel (letterboxed to 4:3) was 0.389 * 0.389 mm). LCD stimulus size thus needed to be enlarged by a factor of 1.23. Stimuli were adjusted to match sizes.

Monitor brightness (as can be set in the monitor’s user menu)

Provides the same amount of radiated energy in a single frame compared to CRTs.

Measure the brightness of a used (and warmed up) experimental CRT with a luminance meter with both a completely black and a completely white screen. Try to match both values with the LCD.

When an exact match is not possible, try to adjust the monitor’s contrast setting accordingly (i.e., usually downregulate the LCD).

In the present study, CRT settings used an on-screen-display brightness setting of 100%; LCDs were set to 9%.

Refresh rate

Multiple complex effects are dependent on the choice of the correct refresh rate, particularly the multiples of the presentation time of a single frame.

Choose the refresh rate to match your CRT or, when designing a new experiment, to match your desired stimulus presentation times as closely as possible.

Example: Stimulus presentation 30 ms; typical refresh rates are 60, 70, 100, 120, 144 Hz. Possible choices are two frames of 60 Hz = 2 * (1/60) = ca. 33 (ms). A better choice would be three frames of 100 Hz = 3 * (1/100) = 30 (ms).

The experiment in the present study used a refresh rate of 100 Hz with presentation times consisting of multiples of 10 ms.

DCC (dynamic capacitance compensation)

Faster gray-to-gray response times at the cost of a constant delay of approx. one frame.

Turn on when possible.

Signals tend to slightly overshoot a few percent brighter than intended, typically for approx. 1 ms.