The transition from algorithmic to memory-based performance is a core component of cognitive skill learning. There has been debate about the temporal dynamics of strategy execution, with some models assuming a race (i.e., independent, capacity unconstrained parallel processing) between algorithm and retrieval, and others assuming a choice mechanism. The authors investigated this issue using a new approach that allows the latency of each algorithm step to be measured, in turn providing new insight into (a) whether there is slowing of 1 or more algorithm steps on trials immediately preceding the 1st retrieval trial for an item, as might be expected if there is a competitive strategy execution process of some type other than a race, and (b) whether there is partial algorithm completion on retrieval trials, as would be expected if the 2 strategies are executed in parallel. Results are uniquely consistent with a strategy choice mechanism involving a competition between the retrieval strategy and the 1st step of the algorithm.Keywords: skill, learning, cued recall, strategy execution, strategy choice An important component of cognitive skill learning-indeed, arguably the signature learning event for many tasks-is the shift from initial use of a slow, multistep algorithm to a faster and subjectively less effortful memory look-up of the answer (direct retrieval). The classic example is arithmetic learning. In doing single-digit multiplication, children may initially perform a repeated addition algorithm, but with sufficient practice they will transition to direct retrieval (e.g., Siegler, 1988). Multiple laboratory studies have confirmed the ubiquity of this shift for arithmetic and arithmetic-like tasks (Delaney, Reder, Staszewski, & Ritter, 1998;Jenkins & Hoyer, 2000;Logan, 1988Logan, , 1992Onyper, Hoyer, & Cerella, 2006;Palmeri, 1997;Reder & Ritter, 1992;Rickard, 1997Rickard, , 1999Rickard, , 2004Rogers, Hertzog, & Fisk, 2000;Schunn, Reder, Nhouyvanisvong, Richards, & Stroffolino, 1997;Touron, Hoyer, & Cerella, 2001.Similar shifts from algorithmic (defined broadly) to retrievalbased performance are believed to occur in a wide variety of nonarithmetic domains, including recall from episodic memory (Rickard & Bajic, 2006), the shift from mnemonically mediated to unmediated memory retrieval (Kole & Healy, 2007;Rickard & Bajic, 2003), lexical decision (Logan, 1988), word reading (e.g., Tao & Healy, 2002), and text comprehension (Rawson, 2004). Similar shifts may occur under item repetition conditions for visuospatial tasks such as mental rotation (Kail, 1986). A reasonable argument can be made, in fact, that any efficiently executed cued recall is a consequence of this shift.Recent efforts to characterize the mechanism underlying this shift make diametrically opposing claims about the dynamics of strategy execution on each trial. One class of models, exemplified by the instance theory of automaticity (Logan, 1988) and its theoretically allied successor, the exemplar-based random walk (EBRW) model (Nosofsky & Palmeri, 199...