Reviews and inspections of software artifacts throughout the development life cycle are effective techniques for identifying defects and improving software quality. While review methods for text-based artifacts (e.g., code) are well understood, very little guidance is available for performing reviews of software diagrams, which are rapidly becoming the dominant form of software specification and design. Drawing upon human cognitive theory, we study how 12 experienced software developers perform individual reviews on a software design containing two types of diagrams: entity-relationship diagrams and data flow diagrams. Verbal protocol methods are employed to describe and analyze defect search patterns among the software artifacts, both text and diagrams, within the design. Results indicate that search patterns that rapidly switch between the two design diagrams are the most effective. These findings support the cognitive theory thesis that how an individual processes information impacts processing success. We conclude with specific recommendations for improving the practice of reviewing software diagrams.