Psychon Bull Rev 2019 Apr;26(2):693-698
University of Richmond, Richmond, VA, USA.
Duffy, Huttenlocher, Hedges, and Crawford (2010, Psychonomic Bulletin & Review, 17, 224-230) examined whether the well-established central tendency bias in people's reproductions of stimuli reflects bias toward the mean of an entire presented distribution or bias toward only recently seen stimuli. They reported evidence that responses were biased toward the long-run mean and found no evidence that they were biased toward the most recent stimuli. Duffy and Smith (2018) reexamine the data using a different analytical strategy and argue that estimates are biased by recent stimuli rather than toward the long-run mean. I argue that this reanalysis misses a true effect of the running mean and that the data are (mostly) consistent with the claims in the original work. I suggest that these results, and many other null results presented by Duffy and Smith, do not have major theoretical significance for the category adjustment model and similar Bayesian models. (Code and data available: https://osf.io/tkqvn .).