Humans treat unreliable filled-in percepts as more real than veridical ones

Abstract

Humans often evaluate sensory signals according to their reliability for optimal decision-making. However, how do we evaluate percepts generated in the absence of direct input that are, therefore, completely unreliable? Here, we utilize the phenomenon of filling-in occurring at the physiological blind-spots to compare partially inferred and veridical percepts. Subjects chose between stimuli that elicit filling-in, and perceptually equivalent ones presented outside the blind-spots, looking for a Gabor stimulus without a small orthogonal inset. In ambiguous conditions, when the stimuli were physically identical and the inset was absent in both, subjects behaved opposite to optimal, preferring the blind-spot stimulus as the better example of a collinear stimulus, even though no relevant veridical information was available. Thus, a percept that is partially inferred is paradoxically considered more reliable than a percept based on external input. In other words: Humans treat filled-in inferred percepts as more real than veridical ones.DOI: http://dx.doi.org/10.7554/eLife.21761.001

Controlling for Participants’ Viewing Distance in Large-Scale, Psychophysical Online Experiments Using a Virtual Chinrest

“…4. Since the mean blind spot diameter is around 4.5°2 2,25 , the center of the blind spots from our results is then 15.84° ± 0.96°, comparable to prior work, in which the blind spot locations are ranged between 14.33 • and 15.52°2 2,23,25 .…”

“…To tackle this issue, we devised a method in which we leverage the fact that the entry point of the optic nerve on the retina produces a blind spot where the human eye is insensitive to light. The center of the blind spot is located at a relatively consistent angle of α = 15° horizontally (14.33° ± 1.3° in Wang et al 22 , 15.5° ± 1.1° in Rohrschneider 23 , 15.48° ± 0.95° in Safran et al 24 , and 15.52° ± 0.57° in Ehinger et al 25 ). Given this, we can calculate an individual's viewing distance from simple trigonometry, as shown in Fig.…”

“…We then calculate the distance between the center of the black square and the center of the red dot (when it disappears from the eye sight). Instead of using α = 15° as the average horizontal blind spot location as found in previous work [22][23][24][25] , we use 13.5° as the average blind spot angle because (1) our method captures the entry point of blind spots (of which the angle should be smaller) instead of the blind spot center, and (2) we calibrated our method by conducting preliminary experiments with a few participants and found that using 13.5° provided us with the most accurate results. The complete formula to calculate the individual viewing distance is…”

An investigation of detection biases in the unattended periphery during simulated driving

“…Traditionally, it is thought that much of peripheral vision is 'filled in' via top-down mechanisms (Komatsu, 2006). However, it has also been reported that people trust unreliable, filledin percepts more than percepts based on external input (Ehinger et al, 2017), suggesting that filling-in may not be the complete mechanism to explain peripheral phenomenology, and that decisional or metacognitive mechanisms are also involved. In our study, perhaps the findings of detection bias in the unattended periphery can also be interpreted as congruent with this account involving mechanisms at the decisional or metacognitive level.…”

Subjective inflation: phenomenology’s get-rich-quick scheme

“…For example, inflation appears to be very similar to perceptual filling-in [10,59] . A recent study showed that filled-in percepts at the blindspot are rated as more reliable than perceptually equivalent, but externally veridical percepts [60] . Though, operationally speaking, this is not necessarily an inflation effect, it shows a similar pattern in which a percept that is based on a less veridical representation of the external world is actually granted a subjective boost.…”