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Abstract:
Pre-attentive comparisons of pitch in auditory sensory memory
are usually investigated by comparing event-related potentials
(ERPs) to standard and deviant stimuli presented in oddball blocks.
Pitch mismatch detection results in mismatch negativity (MMN). This
procedure might overestimate a MMN contribution reflecting pre-
attentive memory processes because of differential states of
refractoriness of respectively recruited neural populations, as has
been repeatedly argued. In this vain, Schröger and Wolff
(1996, NeuroReport) demonstrated minimal memory-comparison-based
MMN contributions for first-order stimuli by investigating
Location-MMN in a controlled paradigm. In addition to standard
procedure, they created a control condition by equiprobably
presenting sounds binaurally with seven different ITDs (each p =
.14), including the standards (p = .86) and deviants (p = .14) of
the MMN conditions. Comparing deviants and controls excluded
potential refractoriness effects and a decomposition of minimal
memory-comparison-based MMN and residual MMN was demonstrated. The
present experiment investigated memory-comparison-based first-
order Frequency-MMN using three conditions: (a) descending Deviant
(500 Hz, p = .1) with a 550 Hz Standard, (b) ascending Deviant
(1179 Hz) with a 1072 Hz Standard and (c) control comprised of a
tonal succession of 10 frequencies between 500 and 1178 Hz (p = .1,
SOA 500ms, duration 50 ms, 70 dB SPL). Controls were physically
identical to Deviants. Results revealed differences between
Deviant-Standard and Deviant-Control comparisons. The data revealed
a decomposition of a memory-comparison-based MMN under the
controlled protocol and a memory-comparison-unrelated residual
MMN.
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