Compared same-different RTs for matching patterns to patterns (PP condition) and for matching descriptions to the same patterns (DP condition). 3 levels of pattern complexity and 3 interstimulus intervals were employed. Ss were 8 undergraduates. Where RTs for the 2 conditions do not differ, it is argued that S may be converting the 1st stimulus from a description to a visual code to perform the matching task. RTs diverge with increased complexity and with lengthened interval. The DP condition is more sensitive to increased complexity, and the PP condition is more sensitive to lengthened interval. (PsycINFO Database Record (c) 2006 APA, all rights reserved)