1. The use of computers to create and display animations/videos in the study of visually guided behaviours has been instrumental in understanding sensory mechanisms underlying complex traits. Using computer displays, scientists are able to create a wide array of colours using three differently coloured lights (Red, Green, Blue [RGB]). While it is possible to generate scenes with RGB displays that mimic animals' colour perceptual experience, this can be problematic because it requires knowledge of the spectral absorbance of the animals' photoreceptor classes, which are often unknown and are difficult to obtain. Even then, stimuli are limited to the central part of the visible spectrum (e.g. ultraviolet (UV) stimuli are not possible).
2. We present a cost‐effective way of modifying a twisted nematic LCD screen that utilizes coloured LEDs, that allows measuring animals' sensitivity to, and discrimination between, wavelengths of light. It has the benefit of not requiring a‐priori knowledge of animals' photoreceptor classes. An LCD screen can be modified by removing the screen's back polarizer (behind the liquid crystal layer) and backlighting the screen with LEDs of two different colours. One of the LED colours transmits through a polarizer with a transmission axis parallel to the screen's front polarizer, and other LED colour transmits through a polarizer orthogonal to the first.
3. To test colour discrimination, one can create a dichromatic stimulus in which both LED colours are ‘ON’ and the current through one LED colour is decreased, while the other is constant, which generated a maximum intensity contrast of 1.84 log units in our setup. To test colour sensitivity, one can create a monochromatic stimulus in which only one LED colour is ‘ON’, which generates a contrast similar to the dichromatic stimulus.
4. This technique overcomes many of the limitations of RGB‐based LCD screens in a cost‐effective way, and allows more accurate testing of the role of colour in visually guided behaviours. Besides the questions in vision research, this setup can answer, it can also be used as an outreach tool in classrooms where children can learn about light, colour, polarization and technology.

中文翻译：

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修改扭曲的向列液晶屏以创建带LED的双色视觉刺激

1. 在视觉引导行为的研究中，使用计算机来创建和显示动画/视频已经有助于理解复杂特征背后的感觉机制。使用计算机显示器，科学家们可以使用三种不同颜色的灯（红色，绿色，蓝色[RGB]）创建各种颜色。尽管可以使用模仿动物的颜色感知经验的RGB显示器生成场景，但这可能会带来问题，因为它需要了解动物感光体的光谱吸收率，而这通常是未知的并且很难获得。即使这样，刺激也仅限于可见光谱的中心部分（例如，不可能进行紫外线（UV）刺激）。
2. 我们提出了一种经济有效的方式来修改利用彩色LED的扭曲向列LCD屏幕，从而可以测量动物对光波长的敏感度和辨别力。它的好处是不需要先验地了解动物的感光体类别。可以通过以下方式修改LCD屏幕：卸下屏幕的后偏光片（位于液晶层的后面），并使用两种不同颜色的LED来对屏幕进行背光照明。其中一种LED颜色通过偏振器透射，且透射轴与屏幕的前偏振器平行，而其他LED颜色通过偏振器透射与第一个偏振器正交的偏振。
3. 为了测试颜色辨别力，可以创建一种双色刺激，其中两个LED颜色均为“ ON”，并且通过一种LED颜色的电流减小，而另一种恒定，这在我们的设置中产生了1.84 log单位的最大强度对比度。为了测试颜色灵敏度，可以创建一种单色刺激，其中只有一种LED颜色为“ ON”，从而产生与二色刺激相似的对比度。
4. 该技术以经济高效的方式克服了基于RGB的LCD屏幕的许多局限性，并允许更准确地测试颜色在视觉引导行为中的作用。除了视觉研究中的问题外，该设置还可以回答问题，还可以用作教室中的外展工具，让孩子们可以学习光，色，偏振和技术。