Journal of cognition
January 1, 2024
Markus Kiefer, Thomas Kammer
In consciousness research, subjective measures (reports of sensory experience) and objective measures (performance on detection or discrimination tasks) are both used to assess visual awareness. While subjective measures sometimes lag behind objective ones, many studies show they converge. Five aspects relevant to achieving convergence are identified, and future work should test the boundary conditions under which convergence or divergence occurs.
PLoS ONE
October 6, 2023
Markus Kiefer, Verena Frühauf, Thomas Kammer
Objective performance measures and subjective ratings of visual awareness yield similar thresholds for detecting and discriminating visual stimuli, supporting the validity of both approaches. In a temporal two-alternative forced choice task, participants' accuracy in detecting stimulus presence and discriminating letter case was compared with their subjective ratings using the Perceptual Awareness Scale (PAS) at high and low contrast. Thresholds for objective and subjective measures showed a comparable pattern across tasks and contrast levels, suggesting that both methods provide converging information about the feature-content of a percept and are likely veridical measures of awareness.
Journal of experimental psychology. Learning, memory, and cognition
February 1, 2023
Markus Kiefer, Marcel Harpaintner, Michaela Rohr et al.
Asking participants to rate their awareness of a briefly flashed, masked word during a semantic priming experiment changes the underlying cognitive processes. In two groups performing a lexical decision task, masked primes were shown for 20, 40, or 60 milliseconds. One group also rated prime visibility trial-by-trial using the Perceptual Awareness Scale; the other did not. Reaction-time and drift-diffusion modeling showed general priming effects on reaction time and drift rate only in the group without the rating task. In the rating group, residual priming effects appeared only on trials where participants reported seeing the prime, and affected non-decisional processing time. The concurrent rating task interferes with semantic priming, likely because it diverts attention to identifying the masked prime.