Visibility Is Not Equivalent to Confidence in a Low Contrast Orientation Discrimination Task

Abstract

In several visual tasks, participants report that they feel confident about discrimination responses at a level of stimulation at which they would report not seeing the stimulus. How general and reliable is this effect? We compared subjective reports of discrimination confidence and subjective reports of visibility in an orientation discrimination task with varying stimulus contrast. Participants applied more liberal criteria for subjective reports of discrimination confidence than for visibility. While reports of discrimination confidence were more efficient in predicting trial accuracy than reports of visibility, only reports of visibility but not confidence were associated with stimulus contrast in incorrect trials. It is argued that the distinction between discrimination confidence and visibility can be reconciled with both the partial awareness hypothesis and higher order thought theory. We suggest that consciousness research would benefit from differentiating between subjective reports of visibility and confidence.

Keywords: confidence; consciousness; metacognition; signal detection theory; visibility; visual awareness.

FIGURE 1

Trial structure.

FIGURE 2

(Upper) Mean discrimination performance as a function of stimulus contrast and scale order (visibility first vs. confidence first, in separate columns). (Lower) Mean subjective reports as a function of trial accuracy (correct vs. incorrect trials, in separate rows), scale order (visibility first vs. confidence first, in separate columns), stimulus contrast (on the x-axis), and scale (visibility vs. confidence, in different colors). Errors bars ⇔ 1 SEM.

FIGURE 3

Distribution of visibility (Left) and confidence (Right) in trials when the other subjective report in the same trial fell below 25% of the scale range.

FIGURE 4

Discrimination sensitivity and metacognitive sensitivity as a function of scale order (visibility first vs. confidence first, in separate panels) and contrast (on the x-axis). Metacognitive sensitivity of visibility and confidence is depicted in different colors. Errors bars ⇔ 1 SEM.

FIGURE 5

Mean metacognitive bias as a function of scale order (visibility first vs. confidence first, in separate panels), contrast (on the x-axis), and scale (visibility vs. confidence, in different colors). Greater values indicate a more conservative reporting strategy. Errors bars ⇔ 1 SEM.

FIGURE 6

Mean gamma correlation coefficients between subjective reports and contrast as a function of scale (visibility vs. confidence, in different colors), scale order (visibility first vs. confidence first, in separate columns), and trial accuracy (correct vs. incorrect trials, in separate rows). Errors bars ⇔ 1 SEM.