Eisner (1970), too, was concerned with the element of resemblance of symbols to their referents. However, his taxonomy
classified symbols into four classes that reflect more than the simple polarity of the continuum. His classes of symbols
are: conventional symbols (abstract signs/symbols with finite referents), representational symbols (iconic symbols
that faithfully depict their referents), connotative symbols (those that distort the image of the referent), and qualitative
symbols (those that are neither signs nor icons per se, but rather are images that establish an atmosphere or evoke feelings). Theorists have quibbled over how and why symbols represent referents and over such points as the functional
imperatives of symbols as either descriptive or depictive (Goodman, 1968; Salomon, 1979b). However, these issues
have not been an object of research, and the categorization
schemes serve research only as obvious variables to be used
in all manner of visual representation studies.