Perceptual confidence judgments reflect self-consistency

We present two separate psychophysical experiments that generate perceptual biases, one where adaptation leads to aftereffects and the other where prior stimulus occurrences are manipulated. We show that confidence judgments perfectly follow changes in perceptual reports and response times, regardless of the nature of the bias. These results suggest that perceivers aim at being self-consistent with themselves rather than correct

Stereoscopic Offset Makes Objects Easier to Recognize

<div><p>Binocular vision is obviously useful for depth perception, but it might also enhance other components of visual processing, such as image segmentation. We used naturalistic images to determine whether giving an object a stereoscopic offset of 15-120 arcmin of crossed disparity relative to its background would make the object easier to recognize in briefly presented (33-133 ms), temporally masked displays. Disparity had a beneficial effect across a wide range of disparities and display durations. Most of this benefit occurred whether or not the stereoscopic contour agreed with the object’s luminance contour. We attribute this benefit to an orienting of spatial attention that selected the object and its local background for enhanced 2D pattern processing. At longer display durations, contour agreement provided an additional benefit, and a separate experiment using random-dot stimuli confirmed that stereoscopic contours plausibly contributed to recognition at the longer display durations in our experiment. We conclude that in real-world situations binocular vision confers an advantage not only for depth perception, but also for recognizing objects from their luminance patterns and bounding contours.</p></div

Appearance of the stimulus in the object-based (left) and rectangular (right) stereoscopic contour conditions.

<p>The target has the same disparity in both cases. In the first case the stereoscopic contour matches the shape of the luminance contour, but not in the second case.</p

Examples of stimuli at 3 different disparities (0, 30 and 120 arcmin) and with the 2 types of stereoscopic contour conditions (object-based and rectangular), against a binocular background (synoptic background not shown).

<p>Arranged for crossed fusion. See Methods for stimulus dimensions, viewing distance, etc.</p

Results of Experiment 1.

<p>Lattice plot of the recognition rate as a function of disparity (in abscise) and display duration (from left to right: 33, 67, 100 and 133ms) for the object-based stereoscopic contour condition (red lines) and rectangular stereoscopic contour condition (blue lines). Thick lines are population mean and standard errors, thin lines are individual observers. The gray dashed line plots the recognition rate for chance performance.</p

Results of Experiment 3.

<p>Recognition rate as a function of disparity (in abscise) for two display durations (left 100ms and right 133ms). Thick lines are population mean and standard errors, thin lines are individual observers. The gray dashed line plots the recognition rate for chance performance.</p

Time course of a trial: observers fixated for 500 ms.

<p>The stimulus was then displayed for 33 to 133 ms and immediately followed by a 500 ms mask. Finally the observers had to report which target object was contained in the stimulus and how confident they were in their answer by moving the black circle cursor. Here the black cursor indicates that the pigeon target was displayed and that the observer is not confident in his/her answer. The figure can be cross-fused.</p

Method used to create the rectangular local backgrounds.

<p>The rectangular local backgrounds behind the target object in each eye were averaged across color channels pixel-by-pixel, after the rectangles were horizontally displaced relative to each other by an amount equal to the target’s disparity.</p