Among the many artforms within the visual arts, Solso focuses exclusively on painted works (paintings, cave paintings, etc.). He completely ignores other forms, such as sculpture, cinema, and dance. His notion of what is "art" is not unproblematic: art is what is exhibited in art museums. Solso draws a line between art and non-art and assumes that certain cognitive processes are operating only in the "art" case. What difference there is between perceiving a face in a Renaissance painting and perceiving a face of someone in the street, is not explained.
In Solso's explanation of how one "understands art", he focus on the cognitive processes. He avoids the area of aesthetics, which to me seems strange. About the only thing he says about differences in aesthetics experience/preference is that people use different background knowledge (having different past experiences) and in that way "understand art" differently. Can't people "understand" a piece of art in the same way but still have totally different aesthetic experiences?
Solso gives his guideline of how to approach art in good faith. But I cannot see how the guideline can be a conclusion from his theoretical framework, which only describes what cognitive processes are at work when art is "understood". Going from descriptive statements to a normative statement is a leap too large in my mind.