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Justin Duncan, Caroline Blais, Daniel Fiset; Right hemisphere horizontal tuning during face processing. Journal of Vision 2019;19(10):229. doi: https://doi.org/10.1167/19.10.229.
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© ARVO (1962-2015); The Authors (2016-present)
Left visual field (LVF) superiority refers to greater face processing accuracy and speed, compared to faces presented in the right VF (e.g., Sergent & Bindra, 1981). It is generally attributed to right hemisphere dominance (e.g., Kanwisher et al., 1997), but few mechanisms have been proposed for this phenomenon (e.g., global/local or low/high spatial frequency processing differences). Recent forays in the face processing literature have however revealed a critical role for horizontal spatial orientations (e.g., Goffaux & Dakin, 2010; Pachai et al., 2013). In line with these results, we verified whether orientation tuning might differ across hemispheres. Thirty participants completed two tasks measuring tuning profiles with orientation bubbles (Duncan et al., 2017). The first task was a 10 AFC identification, to generate a reference profile. The second task introduced lateralized presentations. In this task, a filtered probe face half (one of ten familiar individuals) was presented to either the LVF or RVF, while the other side viewed an average face half (randomized across trials). A target was then presented bilaterally, and participants indicated whether the probe and target were the same person. Central fixation was enforced with eye tracking (M = 97.7%, SD = 3.1% compliant trials) during the probe presentation (60 ms). Classification images were generated to extract diagnostic orientations. The statistical threshold (Zcrit = 2.101, p < 0.05) was established with the Stat4CI toolbox (Chauvin et al., 2005). As expected, horizontals predicted the best accuracy in the reference task (Z = 3.38). This relationship was also observed for the LVF (Z = 3.45), but not for the RVF (Z = −1.92). These results provide novel evidence for right hemisphere horizontal tuning for faces.
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