Passive BCIs allow for the assessment of an operator’s cognitive or affective state in an ongoing human‐computer interaction, without increasing the operator’s task load. The ongoing interaction can then be improved by integrating an implicit information flow from their brain to the machine. The resulting Neuroadaptive Technology optimizes its own state and actions according to changes in the communicated aspects of its operators cognitive and affective state, to support the ongoing interaction. Neuroadaptation can be based on a task‐specific user model that collates mental responses of the user to the associated context. One tool to maintain and refine such a user model during an ongoing interaction is so‐called cognitive probing. I will speak about the development of the research field of Passive Brain‐Computer Interfaces in the last decade and provide an overview of highly‐relevant lab studies in the field of Neuroadaptive Technology and give examples of cognitive probing.