Since each individual’s thinking is idiosyncratic, the teaching of thinking and thinking skills is problematic and
controversial. Salomon (1979b, reprinted 1994) set a theoretical base for discussions of visual thinking in his comments
on symbol systems: “Symbols serve as characters or coding elements . . . (p. 29), [and] . . . some coding elements
of symbol systems can become internalized to serve as vehicles of thought (p. 84).
Conclusions about visual thinking evolve in strange ways. For example, Richard Mayer participated in two very different
studies. One related to conceptual models for teaching computer programming (Bayman & Mayer, 1988). The other
involved cognitive processing during reading (Mayer, 1987). From the two studies, he concluded that “Illustrations may
help readers build useful mental models” (Mayer, 1989, p.240).