RESUMO
The current study investigated whether consonance (imperfect consonance: major third) and dissonance (minor second) would capture attention differently when they occurred as chords (combinations of two tones) that were deviant from their context. In addition, we also examined how task demand would modulate these chords' attentional capture. For this investigation, we used an auditory three-stimulus oddball paradigm in which these chords were presented as deviant stimuli (5% each) among frequent standard (80%) and infrequent target (10%) pure tones. The task difficulty was manipulated by changing pitch intervals between standard and target tones. The results showed that these chords elicited dual-peak P3a, and that consonance enhanced the late phase of P3a compared to dissonance, only when the task demand was high. These findings revealed that deviant consonance and dissonance captured attention differently; in particular, consonance captured attention more strongly than dissonance, and this effect was induced by high task demand. This attentional capture difference between the chord categories was induced through enhanced focus of attention on the pitch dimension of oddball stimuli. In addition, the deviant chords might have been processed by a mechanism similar to that which processes novel stimuli, and these chords' differences might have affected not the novelty detection process, but a process which orients attentional resources to deviant chords, which were recognized as novel stimuli.