Purchase this article with an account.
Matthias Niemeier, Ada Le, Boge Stojanoski; Contrast-specific neural responses underlying the perceptual bias. Journal of Vision 2008;8(6):995. doi: 10.1167/8.6.995.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Visuo-spatial and attentional functions are assumed to be predominantly represented in the right hemisphere because right-hemisphere lesions cause severe deficits such as spatial neglect. However, there is much debate about which neural mechanisms are affected, partially because in healthy people functional and behavioural right-dominant asymmetries are subtle and across participants inconsistent; e.g., most (though not all) people show a slight leftward bias in tasks that require perceptual comparisons of line length, numerosity, and luminance. Here we used a gratingscales task at different levels of pixel noise and event-related potentials to study biases in spatial frequency judgments. We found that leftward bias increased as contrast decreased with increasing pixel noise and that participants with reduced task sensitivity showed a stronger bias than sensitive participants. Also, task sensitivity was correlated with a more pronounced stimulus contrast-related negativity at posterior electrodes 100 ms after stimulus onset, and we observed a task-related component at about 200–300 ms that was modulated by sensitivity as well as contrast. While our data are consistent with a cognitive, possibly attentional account of perceptual bias, future research is required to unravel the complex interactions between attentional and ‘preattentional’ mechanisms of the right hemisphere.
This PDF is available to Subscribers Only