Postersession 1
Poster #: 55
Topic: Error signals
Wednesday, Sep 9, 2015
1st floor

Does sequence foreknowledge or concurrent task affect primacy bias in mismatch negativity (MMN)?

Jade Frost1, Kelly McDonnell, Alexander Provost, & Juanita Todd

1Psychology, University of Newcastle, Newcastle, Australia

The auditory system accumulates evidence about regularity across varying timescales to model predictions about subsequent sound. The evoked-potential component mismatch-negativity (MMN) is elicited upon detection of any pattern-deviation and reflects a ‘prediction-error’. MMN amplitude is proportional to ‘confidence’ in underlying predictions; MMN is largest when patterns are very stable. Using a ‘multi-timescale’ paradigm, we have demonstrated that MMN amplitude does not faithfully reflect sequence stability but instead succumbs to a ‘primacy bias’ that is coupled to initial tone roles. In the paradigm participants hear two-tone sequences in which tones alternate roles of standard (p = .875) and deviant (p = .125). In stable sequences, roles alternate every 2.4min (480 tones per block; 420-standard, 60-deviant). In unstable sequences, roles alternate every 0.8min (160 tones per block; 140-standard, 20-deviant). Primacy bias refers to the observation that only MMN in the first stimulus configuration show the expected stability-modulation: stable>unstable. To date all multi-timescale paradigms have been presented while participants have no knowledge of the sequence structure and watch a silent movie. In this study, we attempted to disrupt the bias by modifying engagement of higher-level brain areas in monitoring longer-term patterns thought to underpin it. The primacy bias pattern did not occur when participants performed a demanding concurrent N-Back task (study-1) or were first informed about the sequence structure (study-2) before watching a silent movie. Our results are interpreted as evidence that engagement of higher-order brain areas is required to make predictions about patterning over longer timescales.