Stimulus properties and visual field location interact to drive performance-independent perceptual confidence

Perceptual confidence tracks decision accuracy, yet it is also systematically shaped by both stimulus properties and spatial location. Using a luminance comparison task, we assessed how multiple stimulus dimensions influence observers' relative brightness judgments and perceptual confidence. These dimensions included visual field location (eccentricity and polar angle) in Experiments 1 and 2, and additionally stimulus noise and overall stimulus strength in Experiment 1. We applied the recently developed relative psychometric function approach to characterize these dimensions' effects on confidence across a range of matched task accuracies, rather than at a single fixed performance level. Observers’ confidence increased with both stimulus noise and visual eccentricity, even as performance range was matched across all conditions. These effects depended on stimulus strength -- i.e., the overall luminance of the stimuli -- revealing interactions among different sources of uncertainty in shaping metacognitive judgments. Together, these results extend previous accounts of the relationship between confidence and accuracy to reveal integration of multiple uncertainty sources and to include suprathreshold stimuli in brightness perception.