“…Response times (RTs) on these "ignored repetition" (IR) trials are usually slower than those on control (C) trials. Since the seminal studies of Neill (1977) and Tipper (1985), a large amount ofresearch has demonstrated that negative priming occurs across a range of stimuli (words, letters, pictures, numbers, nonsense shapes), as well as across a wide variety of task demands (categorization, matching, counting, and target localization; for comprehensive reviews, see Fox, 1995;May, Kane, & Hasher, 1995;Neill & Valdes, 1996;Neill, Valdes, & Terry, 1995;Tipper & Milliken, 1996). Although the methodological variations across many studies have been valuable in demonstrating the generality of negative priming, this diversity has also created difficulties in drawing comparisons across studies (see, e.g., Fox, 1995;May et aI., 1995;Tipper & Milliken, 1996).…”