Cognitive failures are lapses in attention, cognition, and actions that everybody experiences in everyday life. Self-reports are mainly used for assessment but those instruments are memory-biased and more related to personality aspects than to actual behavior. Ambulatory assessment is already used for capturing emotions or addictive behavior, but not yet for cognitive failures. The newly developed Questionnaire for Cognitive Failures in Everyday Life was applied via mobile phones wherein an acoustic signal asked participants 4 times daily to answer 13 questions (...) for 1 week. The new instrument showed satisfying reliability and was compared with a self-report method in terms of correlations with cognitive abilities , personality traits, and demographical aspects. Although further validation is needed, first results are promising and eKFA enriches cognitive failures research. (shrink)