Visual awareness negativity is an early neural correlate of awareness: A preregistered study with two Gabor sizes.
Cognitive, affective & behavioral neuroscience February 1, 2018 DOI: 10.3758/s13415-018-0562-z via PubMed
Summary
AI-generated from the abstractElectrophysiological recordings are commonly used to study the neural correlates of consciousness. Previous research is inconsistent as to whether awareness can be indexed with visual awareness negativity (VAN) at about 200 ms or if it occurs later. This preregistered study tested for VAN and whether stimulus size may account for inconsistent findings. Subjects viewed low-contrast Gabor patches in four visual quadrants; Gabor size (large and small) was varied and calibrated to each subject's threshold. Event-related potentials were derived from trials where subjects localized Gabors correctly, comparing trials with reported awareness versus no awareness. Bayesian analyses revealed very strong evidence for VAN for both sizes, but no evidence for or against an effect of stimulus size. The findings provide evidence for VAN as an early neural correlate of awareness.
Study at a glance
| Characteristics | Experimental study Preregistered Peer reviewed |
|---|---|
| Keywords | Event-related potentials Gabor size Late positivity Visual awareness negativity |
| Key finding | Bayesian analyses revealed very strong evidence for the presence of visual awareness negativity (VAN) for both large and small Gabor sizes, with no evidence for or against an effect of stimulus size. |
Abstract
Electrophysiological recordings are commonly used to study the neural correlates of consciousness in humans. Previous research is inconsistent as to whether awareness can be indexed with visual awareness negativity (VAN) at about 200 ms or if it occurs later. The present study was preregistered with two main aims: First, to provide independent evidence for or against the presence of VAN, and second, to study whether stimulus size may account for the inconsistent findings. Subjects were shown low-contrast Gaussian filtered gratings (Gabor patches) in the four visual quadrants. Gabor size (large and small) was varied in different sessions and calibrated to each subject's threshold of visual awareness. Event-related potentials were derived from trials in which subjects localized the Gabors correctly to capture the difference between trials in which they reported awareness versus no awareness. Bayesian analyses revealed very strong evidence for the presence of VAN for both Gabor sizes. However, there was no evidence for or against an effect of stimulus size. The present findings provide evidence for VAN as an early neural correlate of awareness.