The BCL-100 is a two color LED light source that can provide visual cues of two different colors during tests of visual reflexes in human subjects. The BCL-100 is useful in determining reaction times to light cues of different wavelengths. The device is also useful in determining if reaction times change when subjects are presented with light cues of a different wavelength after the subjects have been habituated to light cues of a familiar color. The intensity, duration, frequency, and color of the light signals emitted by the BCL-100 can be controlled by the same LabScribe2 software used to record the reaction times of subjects. When the light source is connected to the stimulus output of an iWorx Data Recorder, the BCL-100 will emit a green light signal when the polarity of the stimulus voltage is positive, and a red light signal when the polarity of the stimulus voltage is negative.