Cognitive complexity measures based on cognitive informatics are emerging theory in area of software metrics. The first cognitive complexity metric ‘cognitive functional size’ is developed in 2003 by Wang and Shao. This work becomes the milestone of several recent studies in this area. Most of the proposals/proposed metrics uses cognitive weights as the base of their proposals and developed their metrics by adding different features of the programs. This book is the first attempt to combine all the proposed cognitive complexity metrics and present all of them in a formal way. All the presented metrics are compared to each other and evaluated with standards evaluation and validation criteria.