Abolishing the effect of reinforcement delay on human causal learning Marc J. Buehner and Jon May University of Sheffield, Sheffield, UK Associative learning theory postulates two main determinants for human causal learning: contin- gency and contiguity. In line with such an account, participants in Shanks, Pearson, and Dickinson (1989) failed to discover causal relations involving delays of more than two seconds. More recent research has shown that the impact of contiguity and delay is mediated by prior knowledge about the timeframe of the causal relation in question. Buehner and May (2002, 2003) demonstrated that the detrimental effect of delay can be significantly reduced if reasoners are aware of potential delays. Here we demonstrate for the first time that the negative influence of delay can be abolished completely by a subtle change in the experimental instructions. Temporal contiguity is thus not essential for human causal learning. An associative learning analysis of human causal learning postulates two main determinants of judged causal strength: the contingency and the contiguity between the potential cause (cue) and the effect (outcome) (e.g., see Shanks & Dickinson, 1987). Empirical research in the last decades has largely focused on the congruency between cue–outcome contingency and judged causal strength. Early reports suggested that human causal judgements closely track variations in cue-outcome contingency (e.g., Jenkins & Ward, 1965), while more recent studies revealed a more complex picture (e.g., Chapman & Robbins, 1990). In fact, the theoretical and empir- ical relations between contingency and judged causality are still the subject of a hot debate (e.g., Buehner & Cheng, 1997; Cheng, 1997; Dickinson, 2001; Lober & Shanks, 2000; for an overview, see Shanks, Holyoak, & Medin, 1996). In comparison to contingency, contiguity has received relatively little attention. In a seminal paper, Shanks, Pearson, and Dickinson (1989) established the importance of temporal contiguity for human causal induction: They reported that participants could no longer distinguish between causal and noncausal actions when actions and outcomes were separated by more than two seconds. A few follow-up studies employing a similar paradigm (Reed, 1992, 1999) replicated the effect: Reinforcement delays always impaired causal learning. The notion that temporal contiguity is important, or even essential, for human causal learning has been widely accepted in the literature (for the classic Correspondence should be addressed to Marc J. Buehner, School of Psychology, Cardiff University, PO Box 901, Cardiff CF10 3YG, UK. Email: BuehnerM@cardiff.ac.uk This work was funded by ESRC grant R000223692. We thank David Shanks, Helena Matute, and one anony- mous reviewer for helpful comments on an earlier draft.  2004 The Experimental Psychology Society http://www.tandf.co.uk/journals/pp/02724995.html DOI:10.1080/02724990344000123 THE QUARTERLY JOURNAL OF EXPERIMENTAL PSYCHOLOGY, 2004, 57B (2), 179–191 Q2195—QJEP(B)02b18 / Mar 3, 04 (Wed)/ [?? pages – 1 Tables – 2 Figures – 1 Footnotes – 1 Appendix] . Centre single caption • cf. [no comma] Omnipagepro - WTG.