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Published: Jun.11.2011

The Decline Effect: Exploring Why Effects Sizes often Decline Following Repeated Replications

Jonathan Schooler

Although researchers in parapsychology have long acknowledged the peculiar observation that effect sizes tend to decrease with repeated replication of the same or similar paradigms, the more general observation of decline effects across broad swaths of science has yet to receive adequate attention. This talk will review decline effects in parapsychology, biology, and medicine, and consider alternative factors that may underpin this surprisingly broad and currently unexplained phenomenon. Ways to scientifically address this issue will be considered including the development of open repositories for scientific findings in which scientists log study designs before their implementation, and then subsequently report all findings regardless of outcome.

Bio: Jonathan Schooler, PhD is a Professor of Psychology at the University of California at Santa Barbara, where he pursues research on consciousness, memory, the relationship between language and thought, problem-solving, and creativity. He is particularly interested in phenomena at the intersection of psychology and philosophy such as how fluctuations in people’s awareness of their experience mediate mind-wandering and how exposing individuals to philosophical positions alters their behavior. A graduate of Hamilton College, he received his Ph.D. from the University of Washington in 1987 and then joined the psychology faculty of the University of Pittsburgh. He moved to the University of British Columbia in 2004 as a Canada Research Chair in Social Cognitive Science and joined the faculty at UCSB in 2007. He is co- editor of Scientific Approaches to Consciousness, which was published in 1997 by Lawrence Erlbaum.