For students with severe learning disabilities such as visual impairment, unidentified cognitive skill or brain trauma, color-coding the alphabet has been shown to be beneficial to learning versus a monochrome set. It has also been beneficial for students with learning disabilities relating to attention, such as attention deficit hyperactivity disorder.
Color-coding systems such as ABC letters, subjects or parts of the classroom have shown to be useful for the majority of children, specifically those with special needs. However, there are a few rare conditions in which color-coding is obsolete (such as color blindness) or distracting. A student with a sensory processing disorder or an autism spectrum disorder may become overwhelmed or absorbed by the input of letters in varying colors and become incapable of accessing learning. For students with these types of disorders, monochromatic schemes are best.