Suprathreshold perceptual decisions constrain models of confidence
Fig 3
Confidence manipulation checks.
A) Suprathreshold Type 1 task performance. The mean proportion of correct spatial judgements across observers is shown for different trial categories. The left-most bar shows performance for all trials, and the next two bars for trials sorted by confidence, either being in the interval chosen as more confident or declined. B-C) Raw confidence choices, sorted by stimulus properties across the two intervals of a confidence pair. The colour code represents the proportion of “Interval 2” as more confident choices averaged across observers. Confidence choices are plotted as a function of the difference in distance from centre across intervals and difference in inverse dot spread. The distance from centre and dot spread were calculated using the empirical mean and SD of the dots displayed, and binned in the range ±3° for plotting. Gold line: the confidence-indifference contour, where the observer is equally likely to report Interval 1 or 2, calculated from the Full model in the nested logistic regression analysis. B) Comparisons where the number of dots was the same in each interval. C) Comparisons where the number of dots differed, with stimulus information and confidence selectively flipped so that Interval 2 has more dots for plotting purposes. D) Model comparison for the nested logistic regression analysis. AICc scores are reported relative to the Full model (winner) that contained both quantity and quality predictors. The Basic + Quantity and Basic + Quality models only contained one of these predictors and the Basic model contained neither. The results show that both the quantity and quality manipulations affected confidence. Larger positive scores indicate a worse fit. Error bars: ±SEM.