Structural meter perception is pre-attentive

A prominent question in timing research is whether meter perception is possible without attention to meter. So far, research has probed attention effects on meter perception with a surface-based approach that may create confounds between meter and rhythm, and not with a structural approach requiring abstraction from surface patterns. The available pattern of findings suggests that different meter dimensions (meter as beat hierarchy vs. meter as regular cycle length) may yield different attention effects: meter as cycle-length regularity may require attention (it is attentive but not pre-attentive), while meter as beat-hierarchy may be pre-attentive. However, it is unknown whether this dissociation prevails under structural meter processing. We examined attention effects on the EEG correlates of structural meter-processing, considering the two dimensions of meter perception: hierarchy and cycle-length. While the results for hierarchy violations were inconclusive, cycle-length violations induced pre-attentive, but not attentive, responses. These pre-attentive responses corresponded to late ERPs (300-600 ms), consistent with deep, structural meter-processing. Our findings highlight the importance of pre-attentive processing in meter perception, and they raise the hypothesis of dissociation between surface- and structure-based meter processing.