Falko Rheinberg is a motivation psychologist at the University of Potsdam and one of the central figures in the German-language flow research tradition. His most significant contribution to the field is the flow-short-scale (Kurzskala Flow-Erleben, FKS), developed with Regina Vollmeyer and engeser in the early 2000s. The FKS enabled the field to measure flow efficiently in everyday contexts and became the dominant instrument for ESM studies outside sport psychology.
Theoretical orientation
Rheinberg's approach to flow sits at the intersection of motivation psychology and the study of subjective experience. He has consistently treated flow as related to but distinct from intrinsic motivation — not a synonym for it. In his analysis, intrinsic motivation can persist even without the full absorption and effortlessness characteristic of flow, and flow can be experienced by people who began an activity extrinsically motivated. This distinction matters for measurement: scales that conflate flow with intrinsic motivation introduce construct validity problems.
This theoretical independence distinguishes Rheinberg's position from some American treatments of flow that fold it together with self-determination-theory constructs. deci and ryan's framework treats intrinsic motivation as the motivational basis for flow, while Rheinberg's model allows them to co-vary without being identical.
The Flow Short Scale
Rheinberg, Vollmeyer, and engeser developed the flow-short-scale as a practical solution to a specific measurement problem: the dominant instruments at the time, jackson's flow-state-scale and dispositional-flow-scale, were designed for sport contexts and contained too many items for use in ecological momentary assessment. The FKS's 13-item format, with two dimensions (flow experience proper and an anxiety subscale), was brief enough to complete in the two or three minutes available during an ESM signal without disrupting the activity being studied.
The FKS has been validated in multiple languages and used in hundreds of studies, particularly in German-speaking countries. Its brevity and non-sport design made it the natural instrument for studying flow in academic work, creative tasks, and everyday activities.
Critical contributions
Rheinberg's longitudinal ESM work produced findings that complicated simpler accounts of flow. His data showed that challenge-skill balance, while a reliable predictor on average, does not universally produce flow across individuals or moments — some individuals report flow outside the theoretically predicted challenge-skill zone. This contributed to the flow-state-vs-spectrum-debate about whether flow is a categorical state or a continuous dimension. moneta's parallel ESM analyses developed similar critical arguments using different datasets.
Position in the lineage
Rheinberg connects the experience-sampling-method tradition developed by csikszentmihalyi to European motivation psychology, bringing rigorous psychometric discipline to measurement while maintaining theoretical independence on the intrinsic motivation question. His collaboration with engeser produced the most widely used academic reference in the field, advances-in-flow-research, and his FKS remains the instrument of choice when brevity and non-sport applicability are required.