Digitized photographs of snowflakes were presented for a recognition test after retention intervals of varying durations. While overall accuracy and discrimination remained constant, as the retention interval increased, primacy increased from chance to reliably better than chance while recency decreased to chance levels. A variation of Murdock's (1960) distinctiveness model accounted for the changing primacy and recency effects observed in both between-and within-subjects designs. The generality of the model was examined in two different paradigms: lexical access during sentence processing, and free recall in the continual distractor paradigm. In both cases, the model made accurate qualitative predictions for both latency and accuracy measures.Recently, there has been a flurry of articles concerned with the idea that recollection of an item, in a variety of different tasks and paradigms, depends critically on its distinctiveness-that is, on the degree to which a given item stands out among the other items in the set (e.g., Crowder & Neath, 1991; Gardiner & Hampton, 1988;Glenberg & Swanson, 1986; Johnson, 1991;McDaniel & Einstein, 1986;Neath & Crowder, 1990;Schmidt, 1991). The idea, of course, is not new: first formulated verbally by Koffka (1935), and then quantitatively by Murdock (1960), the central idea can be traced back to Aristotle (Burnham, 1888). In this paper, I demonstrate that a variation of Murdock's model of distinctiveness can account for serial position effects observed in recognition memory and that this model can be applied to other paradigms as well.Murdock (1960) defined distinctiveness as the extent to which a given stimulus "stands out" (p. 17) from other stimuli and noted that "the concept of distinctiveness refers to the relationship between a given stimulus and one or more comparison stimuli, and if there are no comparison stimuli the concept of distinctiveness is simply not applicable" (p. 21). By means of an analogy with visual perception, one can demonstrate that just as the insertion of space between items in the visual field should make them more distinctive spatially, the addition of an interval between items in a list will make them more distinctive temporally (Glenberg & Swanson, 1986;Neath & Crowder, 1990). An item can also be made more disSome of these results were presented at the 33rd annual meeting of the Psychonomic Society, St. Louis, November 1992. I wish to thank Vincent Biedron, Michelle Hrabovsky, and Victoria Smejkal for running the subjects in Experiment I, and Kimberly Croley for running the subjects in Experiment 2. In addition, I thank Robert G. Crowder and Aimee M. Surprenant for helpful and insightful discussions. Correspondence concerning this article may be addressed to 1. Neath, 1364 Psychological Sciences Building, Purdue University, West Lafayette, IN 47907-1364 (e-mail: neath@brazil.psych.purdue.edu).tinct by the manipulation of physical properties (Calkins, 1894;von Restorff, 1933), or, presumably, of any other dimension of interest. This view of distincti...