title: On the interpretation of removable interactions: a survey of the field 33 years after Loftus.
abstract: In a classic 1978 Memory &                         Cognition article, Geoff Loftus explained why noncrossover interactions are removable. These removable interactions are tied to the scale of measurement for the dependent variable and therefore do not allow unambiguous conclusions about latent psychological processes. In the present article, we present concrete examples of how this insight helps prevent experimental psychologists from drawing incorrect conclusions about the effects of forgetting and aging. In addition, we extend the Loftus classification scheme for interactions to include those on the cusp between removable and nonremovable. Finally, we use various methods (i.e., a study of citation histories, a questionnaire for psychology students and faculty members, an analysis of statistical textbooks, and a review of articles published in the 2008 issue of Psychology and                         Aging) to show that experimental psychologists have remained generally unaware of the concept of removable interactions. We conclude that there is more to interactions in a 2 × 2 design than meets the eye.
authors: Department of Psychology, University of Amsterdam, Roetersstraat 15, 1018 WB, Amsterdam, The Netherlands. EJ.Wagenmakers@gmail.com
authors: Eric-Jan
authors: EJ
authors: Wagenmakers
authors: Angelos-Miltiadis
authors: AM
authors: Krypotos
authors: Amy H
authors: AH
authors: Criss
authors: Geoff
authors: G
authors: Iverson
mesh_terms: D003072:Cognition Disorders / Q000266:history; D049673:History, 20th Century; D006801:Humans; D011939:Mental Recall / Q000502:physiology; D008960:Models, Psychological; D011589:Psychology, Experimental / Q000266:history; D012107:Research Design / Q000592:standards / Q000639:trends