A central feature of consciousness is the association between external events and subjective experiences of content. These experiences range from low level (detection) to high level (identification). For example, a visual experience may range from seeing something on a computer screen (detection) to seeing the digit 3 (identification). In research, neural processes that correlate with these experiences are called neural correlates of consciousness (NCCs). In vision, a candidate NCC is the visual awareness negativity (VAN) that is derived from event-related potentials, occurring about 200 ms after stimulus onset over posterior electrode sites. Because previous research does not resolve whether VAN is more sensitive to low-level experiences (detection awareness) than high-level experiences (identification awareness), we conducted two preregistered experiments. In both experiments, two staircases continuously adjusted stimulus opacity to separately target detection awareness and identification awareness. In Experiment 1, subjects viewed either individual digits (N = 15) or individual letters or digits (N = 15). For both types of stimuli, VAN was similarly sensitive to detection awareness and identification awareness. As a follow up, Experiment 2 (N = 28) examined whether stimulus size affects VAN to identification awareness using digit stimuli. Results showed identification VAN for both digit sizes, and VAN was unaffected by stimulus size. These results confirm the sensitivity of VAN to both low-level experiences (detection) and high-level experiences (identification). However, results emphasize the limited specificity of VAN in separating between low-level and high-level experiences, suggested by the similarity of VAN in both conditions.

The neurological basis for perceptual awareness remains unclear, and theories disagree as to whether sensory cortices per se generate awareness. Critically, neural activity in the sensory cortices is only a neural correlate of consciousness (NCC) if it closely matches the contents of perceptual awareness. Research in vision and touch suggest that contralateral activity in sensory cortices is an NCC. Similarly, research in hearing with two sound sources (left and right) presented over headphones also suggests that a candidate NCC called the auditory awareness negativity (AAN) matches perceived location of sound. The current study used 13 different sound sources presented over loudspeakers for natural localization cues and measured event-related potentials to a threshold stimulus in a sound localization task. Preregistered Bayesian mixed models provided moderate evidence against an overall AAN and very strong evidence against its lateralization. Because of issues regarding data quantity and quality, exploratory analyses with aggregated data from multiple loudspeakers were conducted. Results provided moderate evidence for an overall AAN and strong evidence against its lateralization. Nonetheless, the interpretations of these results remain inconclusive. Therefore, future research should reduce the number of conditions and/or test over several sessions to procure a sufficient amount of data. Taken at face value, the results may suggest issues with AAN as an NCC of auditory awareness, as it does not laterally map onto experiences in a free-field auditory environment, in contrast to the NCCs of vision and touch.

Humans have conscious experiences of the events in their environment. Previous research from electroencephalography (EEG) has shown visual awareness negativity (VAN) at about 200 ms to be a neural correlate of consciousness (NCC). However, when considering VAN as an NCC, it is important to explore which particular experiences are associated with VAN. Recent research proposes that VAN is an NCC of lower-level experiences (detection) rather than higher-level experiences (identification). However, previous results are mixed and have several limitations. In the present study, the stimulus was a ring with a Gabor patch tilting either left or right. On each trial, subjects rated their awareness on a three-level perceptual awareness scale that captured both detection (something vs. nothing) and identification (identification vs. something). Separate staircases were used to adjust stimulus opacity to the detection threshold and the identification threshold. Bayesian linear mixed models provided extreme evidence (BF10 = 131) that VAN was stronger at the detection threshold than at the identification threshold. Mean VAN decreased from -2.12 microV [-2.86, -1.42] at detection to -0.46 microV [-0.79, -0.11] at identification. These results strongly support the claim that VAN is an NCC of lower-level experiences of seeing something rather than of higher-level experiences of specific properties of the stimuli. Thus, results are consistent with recurrent processing theory in that phenomenal visual consciousness is reflected by VAN. Further, results emphasize that it is important to consider the level of experience when searching for NCC.