Subjective and objective measures of visual awareness converge across feature types and task modes
Tue—HZ_9—Talks4—3701
Presented by: Markus Kiefer
In consciousness research, such as the study of masked priming, various methods are used to measure the content of visual awareness: Subjective measures rely on the observer's introspection regarding the perceptual experience, whereas objective measures rely on the observer's performance in accurately detecting or discriminating the stimulus of interest over a series of trials. The most appropriate measure of awareness is currently debated. To contribute to this debate, we compared subjective and objective awareness measures across different stimulus features using a temporal two-alternative forced-choice (2-AFC) task mode as well as a classical two-category task mode on single stimuli. Compared to the two-category single-stimulus task mode, the temporal 2-AFC task mode is thought to specifically minimize biases due to unconscious processing. Thresholds based on subjective ratings with the Perceptual Awareness Scale (PAS) and on performance accuracy were determined for detection (stimulus presence, only temporal 2AFC task mode) and discrimination (letter case, both task modes) tasks, performed on masked word stimuli. We found a comparable pattern of thresholds across tasks and task modes for objective and subjective measurements of awareness. Although subjective measures have sometimes lagged behind objective measures in previous studies, the present experiments demonstrate a convergence of measures. The observed similarity of thresholds across task modes confirms that psychophysical and subjective measures of awareness provide converging, and thus most likely equally veridical, measures of awareness. Our work thus refutes arguments that subjective measures should be preferred to objective measures in consciousness research because of their greater specificity.
Keywords: psychophysics, consciousness, visual masking, visual awareness ratings, perceptual awareness scale