Effects of sad mood on time-based prospective memory Matthias Kliegel and Theodor Ja Èger University of Zurich, Switzerland Louise H. Phillips University of Aberdeen, UK Esther Federspiel, Adrian Imfeld, Marianne Keller, and Daniel Zimprich University of Zurich, Switzerland Very little is known about the influence of emotional factors on prospective memory (PM) performance. We used a mood induction (neutral or sad) to examine the effects of sad mood on time-based PM performance. Based on Ellis and Ashbrook's (1988) resource allocation model, we hypothesised an adverse effect of sad mood on PM performance. Results revealed that participants who responded to the sad mood induction procedure showed reduced PM performance that mainly resulted from a decreased timeliness of PM responses, but only in the first half of the task. Mood effects on PM could be explained in terms of reduced and less accurate monitoring. Implications for concepts of PM and the assessment of emotional after-effects are discussed. Prospective memory (PM) is defined as the ability to remember to perform activities in the future (Brandimonte, Einstein, & McDaniel, 1996). Remem- bering to attend a meeting or to post a letter are everyday examples of PM tasks. In fact, PM problems are the most frequent memory failures in everyday life (Kliegel & Mi. Martin, 2003). The literature (e.g., Einstein & McDaniel, 1996) distinguishes between event-based PM tasks which demand the self-initiated execution of the intended action after the appearance of an externally presented cue (e.g., the appearance of a target word), and time-based PM tasks demand the Correspondence should be addressed to Matthias Kliegel, Department of Psychology, University of Zurich, Freiensteinstrasse 5, CH-8032 Zu Èrich, Switzerland; e-mail: m.kliegel@psychologie.unizh.ch We thank Caroline Bra Èndli for her assistance in data collection # 2005 Psychology Press Ltd http://www.psypress.com/cogemotion DOI:10.1080/02699930500233820 COGNITION AND EMOTION 2005, 19 (8), 1199±1213