When quantitatively measuring how humans experience the cooperation with intelligent systems, validated instruments grounded in established fields such as human-automation interaction research are needed. We derived Subjective Information Processing Awareness (SIPA) from core conceptions of Situation Awareness. SIPA describes to what extent interacting with an intelligent system enables users to experience 1) Transparency 2) Understandability and 3) Predictability of the system’s information processing. The SIPA concept was operationalized as a 6-item scale. The goal of the present research was to examine the psychometric characteristics of the SIPA scale as well as the internal structure based on three samples from independent experiments with N = 162 participants. The SIPA scale showed possible applicability both as (a) a three-facet scale (three highly correlated facets) and (b) a one-dimensional scale as well as high reliability. Construct validity with related constructs such as explanation satisfaction or trust was expectedly high. Based on the results, the SIPA scale appears to be a promising tool for research on cooperative AI systems. We discuss what role SIPA and different effects of explanations on experienced traceability may have for future studies of, e.g., Human-AI teams.