In the first part of Understanding Media, McLuhan also states that different media invite different degrees of participation on the part of a person who chooses to consume a medium. Some media, such as film, were “hot” - that is, they enhance one single sense, in this case vision, in such a manner that a person does not need to exert much effort in filling in the details of a movie image. McLuhan contrasted this with “cool” TV, which he claimed requires more effort on the part of viewer to determine meaning, and comics, which due to their minimal presentation of visual detail require a high degree of effort to fill in details that the cartoonist may have intended to portray. Wikipedia