Hierarchical timescales of statistical learning revealed by mismatch negativity to auditory pattern deviations

Publication date: Available online 27 September 2018Source: NeuropsychologiaAuthor(s): Kaitlin Fitzgerald, Juanita ToddAbstractThe amplitude of mismatch negativity (MMN) elicited following an unexpected sound reflects a pattern-violation signal that will increase with estimated precision. Precision is inversely related to environmental variance, and should be higher the longer that current regularities have been stable. However, MMN amplitude can be impacted by initial learning such that the relative probability of sounds when first encountered distorts the precision estimates later associated with those sounds. The present study tested the hypothesis that MMN to a pattern violation would be differentially sensitive to both local and global patterning within a sequence, depending on whether the sound was common or rare at sequence onset. Sound sequences consisted of two levels of nested regularity: (1) two tones alternated probabilities as the local standard (p = 0.875) and deviant (p = 0.125), and (2) these alternations occurred regularly across four blocks of 2.4 mins (stable components) or twelve blocks of 0.8 mins (unstable components). Sequences were delivered first in an unstable-stable (“increasing-stability”) and next a stable-unstable (“decreasing-stability”) structure, both inducing a violation to the regular block length at the transition between components. MMN to the tone initially heard as a common repeating standard when later heard as a devia...

Source: Neuropsychologia - October 5, 2018 Category: Neurology Source Type: research