Abstract: Apparatuses and methods are provided for measuring the critical flicker fusion frequency of a subject. The apparatus in one aspect comprises two or more light sources, each flickering at a different predetermined frequency. The subject selects one light source from an array of light sources defining a first range of frequencies, the selection representing the light source of lowest frequency that appears as fused to the subject. The frequencies of the light sources are adjusted to second predetermined frequencies defining a second range. The subject selects the light source of lowest frequency that appears as fused to the subject. The frequency value of the second selection can be assigned as the subject's critical flicker fusion frequency.