AUTHOR=Venezia Jonathan H., Saberi Kourosh , Chubb Charles , Hickock Greg TITLE=Response Bias Modulates the Speech Motor System during Syllable Discrimination JOURNAL=Frontiers in Psychology VOLUME=3 YEAR=2012 URL=https://www.frontiersin.org/journals/psychology/articles/10.3389/fpsyg.2012.00157 DOI=10.3389/fpsyg.2012.00157 ISSN=1664-1078 ABSTRACT=
Recent evidence suggests that the speech motor system may play a significant role in speech perception. Repetitive transcranial magnetic stimulation (TMS) applied to a speech region of premotor cortex impaired syllable identification, while stimulation of motor areas for different articulators selectively facilitated identification of phonemes relying on those articulators. However, in these experiments performance was not corrected for response bias. It is not currently known how response bias modulates activity in these networks. The present functional magnetic resonance imaging experiment was designed to produce specific, measureable changes in response bias in a speech perception task. Minimal consonant-vowel stimulus pairs were presented between volume acquisitions for same-different discrimination. Speech stimuli were embedded in Gaussian noise at the psychophysically determined threshold level. We manipulated bias by changing the ratio of same-to-different trials: 1:3, 1:2, 1:1, 2:1, 3:1. Ratios were blocked by run and subjects were cued to the upcoming ratio at the beginning of each run. The stimuli were physically identical across runs. Response bias (criterion,