Visual comprehension is the characteristic that deals with how efficiently and effectively users are able to grasp the underlying design intent along with the interactions to explore the visually represented information. To assess comprehension i.e. to measure this seemingly immeasurable factor of visualization systems, we are proposing a set of criteria based on a detailed analysis of information flow from the raw data to the cognition of information in human mind. Our comprehension criteria are adapted from thepioneering work of two eminent researchers - Donald A. Norman and Aaron Marcus, who have investigated the issues of human perception and cognition, and visual effectiveness respectively. These proposed criteria are refined by experts? opinion in order to compose a minimal evaluation set that is then applied to a bioinformatics visualization study tool to show the efficacy of criteria in assessing comprehension in a more quantitative manner.