Memory trace formation for abstract auditory features and its consequences in different attentional contexts

The capacity for abstraction is vital for adaptive behavior. Based on behavioral data and event-related potentials (ERPs), the present study investigates the brain's ability to encode abstract auditory rules with a dynamic approach in which rules constantly emerge and vanish. In successive conditions, abstract rules are task-irrelevant and task-relevant. Results show that as few as two consecutive exemplars of an abstract feature (frequency relation between successive tones) are sufficient for rule extraction. The extraction of just emerging rules is independent of the amount of attention devoted to the rules, and it is not modulated by further rule-conforming exemplars. The extracted rules are immediately applied, as evidenced by the interference of task-irrelevant rule violations with concurrent mental processes (distraction condition) and by the conscious detection of task-relevant violations (detection condition). The ability to rapidly encode abstract rules and to detect presumably important rule-violating events underlines the brain's adaptability to the environmental demands. (C) 2008 Elsevier B.V. All rights reserved.