Research Article When Memory Fails, Intuition Reigns Midazolam Enhances Implicit Inference.pdfVIP

PSYCHOLOGICAL SCIENCE Research Article When Memory Fails, Intuition Reigns Midazolam Enhances Implicit Inference in Humans Michael J. Frank,1 Randall C. O’Reilly,2 and Tim Curran2 1Department of Psychology and Program in Neuroscience, University of Arizona, and 2Department of Psychology, University of Colorado at Boulder ABSTRACT—People often make logically sound decisions hippocampus (Frank, Rudy, Levy, O’Reilly, 2005; Frank, using explicit reasoning strategies, but sometimes it pays to Rudy, O’Reilly, 2003; Frank, Seeberger, O’Reilly, 2004). rely on more implicit ‘‘gut-level’’ intuition. The transitive This explains why pigeons with hippocampal damage continue inference paradigm has been widely used as a test of ex- to respond transitively (Strasser, Ehrlinger, Bingman, 2004), plicit logical reasoning in animals and humans, but it can and why humans can respond transitively even when they are also be solved in a more implicit manner. Some researchers prevented from becoming explicitly aware of hierarchical rela- have argued that the hippocampus supports relational tionships (and therefore from employing logical reasoning; memories required for making logical inferences. Here we Frank, Rudy, et al., 2005). In the study reported here, we in- show that the benzodiazepene midazolam, which inacti- vestigated in humans the effects of the drug midazolam, which vates the hippocampus, causes profound explicit memory has potent amnestic properties and transiently deactivates the deficits in healthy participants, but enhances their ability hippocampus (Hirshman, Passannante, Arndt, 2001; Ko- in making implicit transitive inferences. These results are bayashi, Fujito, Matsuyama, Aoki,