Differential processing of local and global
visual features is well established. Global precedence effects, differences in
event-related potentials (ERPs) elicited when attention is focused on local versus global levels, and hemispheric specialization for local and global features all indicate that relative scale of detail is an important distinction in
visual processing. Observing analogous differential processing of local and global auditory information would suggest that scale of detail is a general organizational principle of
the brain. However, to date the research on auditory local and global processing has primarily focused on music
perception or on the
perceptual analysis of relatively higher and lower
frequencies. The study described here suggests that
temporal aspects of auditory stimuli better capture the local-global distinction. By combining short (40 ms)
frequency modulated tones in series to create global auditory patterns (500 ms), we independently varied whether pitch increased or decreased over short time spans (local) and longer time spans (global).
Accuracy and reaction time measures revealed better performance for global judgments and asymmetric interference that were modulated by amount of pitch change. ERPs recorded while participants listened to identical
sounds and indicated the direction of pitch change at the local or global levels provided evidence for differential processing similar to that found in ERP studies employing hierarchical
visual stimuli. ERP measures failed to provide evidence for
lateralization of local and global auditory
perception, but differences in distributions suggest preferential processing in more
ventral and
dorsal areas respectively.
