Electrophysiological correlates of detection and identification awareness for digits and letters

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. Previous research suggests that VAN is more sensitive to low-level experiences (detection) than high-level experiences (identification). Because previous results are limited, two preregistered experiments were conducted. In both experiments, two separate staircases continuously adjusted stimulus opacity to either detection- or identification thresholds. Detection awareness referred to experiencing something rather than nothing. Identification awareness referred to experiencing the identity of the stimulus rather than not experiencing its identity. Experiment 1 (N = 30) showed that VAN was similarly sensitive to detection awareness and identification awareness. This was shown for a digit task and for a letter task. Experiment 2 (N = 28) used the same digit task as in Experiment 1 with two stimulus sizes. Results found 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.