Reported is an Aptitude Treatment Instruction (ATI) Study designed to evaluate the aptitude of verbal comprehension in terms of two unitary complex science diagram types: a single complex block word diagram and a single complex picture word diagram.. ATI theory and research indicate that different effective instructional treatments tend to help some kinds of learners more than others. These findings have cost, facility, and personal implications for the design and implementations of science curriculums and the development of individualized instructional programs. Eighty-two high school science subjects were randomly assigned to a word or word-picture diagram (i.e., pathway or cyclic schema with adjunct questions) treatment. Multiple regression analysis of posttest scores (predictors: verbal ability and pretest scores) supported the a priori hypothesis that low verbal subjects seemed to benefit from certain verbal and pictorial referents. Higher verbal ability subjects appeared to be less dependent on the investigated pictorial referent type in terms of the verbal (nonpictorial) criterion test. (Author/PEB)