| Abstract: | G. R. Loftus (see record 1986-05498-001), R. S. Bogartz (see record 1990-09037-001), and others have questioned forgetting comparisons based on tests of interaction between retention and a second variable. A method for comparing forgetting between conditions on the basis of an article by N. H. Anderson (1963) is presented here. The shape method compares the underlying "shapes" of the performance curves. Anderson's shape method is outlined for memory studies, and its inherent assumptions are stated. A statistical test is developed to apply the shape method to realistic situations in which zero retention interval or asymptotic performance data are not available. A power analysis varied the memory curve shape, sample size, and standard deviation and demonstrated the method's ability to detect shape differences. Application to a recent study claiming a forgetting difference yielded the opposite conclusion. Theoretical and practical limitations of Loftus's and Bogartz's methods are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) |
