Visual representations are a familiar element of daily life and particularly beneficial as illustrations in science textbooks. In this case, learners draw on human dimensions such as cognitive style (CS) and prior knowledge (PK) when engaging in visual thinking. This study aimed to compare and explore the relationships among the format aspect (e.g. searching process), the content aspect (e.g. comprehension and interpretation), and the subject aspect (CS and PK) as applied when viewing two given hierarchical chromosome structure illustrations: the Mami version and the miMa version. Interviews were conducted with 7th graders given the illustrations. Participants' CS and PK were determined by Group Embedded Figures Test and Prior Knowledge Assessment. The results were consonant with the framework that most participants' searching process was conducted from top to bottom for both illustrations. Second, participants from both CS groups and low PK score group (PKL) were more capable of comprehending the Mami version than the miMa version. Third, learners typically applied a decomposed strategy in interpreting the Mami version. Fourth, the field dependent group and PKL group require further guidance when interpreting the miMa version. The implications of this study will focus on curriculum design, textbook or instructional materials, and instruction.