E V ector-related sequence learning in a bimanual-bisequential serial reaction time task

In a bimanual-bisequential version of the serial reaction time (SRT) task participants performed two uncorrelated key-press sequences simultaneously, one with Wngers of the left hand and the other with Wngers of the right hand. Participants responded to location-based imperative stimuli. When two such stimuli appeared in each trial, the results suggest independent learning of the two sequences and the occurrence of intermanual transfer. Following extended practice in Experiment 2, transfer of acquired sequence knowledge was not complete. Also in Experiment 2, when only one stimulus appeared in each trial specifying the responses for both hands so that there was no basis for separate stimulus–stimulus or separate response–eVect learning, independent sequence learning was again evident, but there was no intermanual transfer at all. These Wndings suggest the existence of two mechanisms of sequence learning, one handrelated stimulus-based and the other motor-based, with only the former allowing for intermanual transfer. EVector-related sequence learning in a bimanual-bisequential serial reaction time task The ability to acquire knowledge about sequential regularities is one of the characteristic features of human cognition. Since its introduction by Nissen and Bullemer (1987) the serial reaction time (SRT) task has become the dominant tool for exploring the mechanisms underlying sequence learning (for reviews see, e.g., Clegg, DiGirolamo, & Keele, 1998; HoVmann, 2001; Rhodes, Bullock, Verwey, Averbeck, & Page, 2004). On each trial in a typical SRT experiment a stimulus appears in one of several locations, and participants are instructed to press the key assigned to that location as quickly as possible. The critical manipulation entails the introduction of structural redundancies in the stimulus sequence, typically the repetition of a Wxed sequence. Following suYcient practice, sequence learning is usually demonstrated by a decrease of performance when the Wxed sequence is replaced with a random sequence. Because of the nature of a typical SRT task a Wxed sequence of stimuli (S1–S2–S3–S4.) is confounded with a Wxed sequence of responses (R1–R2–R3–R4.) as well as with regularities between responses and subsequent stimuli (Ri–Si+1). Therefore, performance beneWts for structured sequences can result both because participants learn to anticipate forthcoming stimuli (S–S learning; R– S learning) and because they learn to prepare forthcoming responses in advance (R–R learning). Indeed, there is evidence that each of these regularities contributes to sequence learning (S–S learning: e.g., Howard, Mutter, & Howard, 1992; Koch & HoVmann, 2000; Remillard, 2003; R–R learning: e.g., HoVmann & Koch, 1997, 1998; HoVmann, Martin, & Schilling, 2003; HoVmann & Sebald, 1996; Nattkemper & Prinz, 1997; Rüsseler & Rösler, 2000; R–S learning: e.g., Hazeltine, 2002; HoVmann, Sebald, & Stöcker, 2001; Stöcker & HoVmann, 2004; Stöcker, Sebald, & HoVmann, 2003; Ziessler, 1998; Ziessler & Nattkemper, 2001). The question, then, arises to M. P. Berner · J. HoVmann Department of Psychology, University of Würzburg, Würzburg, Germany M. P. Berner (&) Institut für Psychologie III der Universität Würzburg, Röntgenring 11, 97070 Würzburg, Germany e-mail: berner@psychologie.uni-wuerzburg.de