Recent research revealed that individual cognitive differences affect visual behavior and task performance of picture passwords within conventional interaction realms such as desktops and tablets. Bearing in mind that mixed reality environments necessitate from end-users to perceive, process and comprehend visually-enriched content, this paper further investigates whether this new interaction realm amplifies existing observed effects of individual cognitive differences towards user interactions in picture passwords. For this purpose, we conducted a comparative eye tracking study (N = 50) in which users performed a picture password composition task within a conventional interaction context vs. a mixed reality context. For interpreting the derived results, we adopted an accredited human cognition theory that highlights cognitive differences in visual perception and search. Analysis of results revealed that new technology realms like mixed reality extend and, in some cases, amplify the effect of human cognitive differences towards users’ visual and interaction behavior in picture passwords. Findings can be of value for improving future implementations of picture passwords by considering human cognitive differences as a personalization factor for the design of user-adaptive graphical passwords in mixed reality.