Subjective and objective measures of visual awareness converge.

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.

Study at a glance

Abstract

Within consciousness research, the most appropriate assessment of visual awareness is matter of a controversial debate: Subjective measures rely on introspections of the observer related to perceptual experiences, whereas objective measures are based on performance of the observer to accurately detect or discriminate the stimulus in question across a series of trials. In the present study, we compared subjective and objective awareness measurements across different stimulus feature and contrast levels using a temporal two-alternative forced choice task. This task has the advantage to provide an objective psychophysical performance measurement, while minimizing biases from unconscious processing. Thresholds based on subjective ratings with the Perceptual Awareness Scale (PAS) and on performance accuracy were determined for detection (stimulus presence) and discrimination (letter case) tasks at high and low stimulus contrast. We found a comparable pattern of thresholds across tasks and contrasts for objective and subjective measurements of awareness. These findings suggest that objective performance measures based on accuracy and subjective ratings of the visual experience can provide similar information on the feature-content of a percept. The observed similarity of thresholds validates psychophysical and subjective approaches to awareness as providing converging and thus most likely veridical measures of awareness.