Experience can change the 'light-from-above' prior

Abstract

To interpret complex and ambiguous input, the human visual system uses prior knowledge or assumptions about the world. We show that the 'light-from-above' prior, used to extract information about shape from shading is modified in response to active experience with the scene. The resultant adaptation is not specific to the learned scene but generalizes to a different task, demonstrating that priors are constantly adapted by interactive experience with the environment.

Where is the light? Bayesian perceptual priors for lighting direction

“…In each case, the estimated prior is biased towards the upper left, in agreement with previous findings on group average data (Mamassian & Landy 2001). Thus, the left biases observed in each posterior in figure 4 and in Mamassian & Goutcher (2001), as well as the left and right biases reported in Sun & Perona (1998) and Adams et al (2004), are probably due to a bias in each observer's prior, rather than a bias in the likelihood function. The estimated prior concavity preferences for all observers were within the rangepðc 1 ÞZ 0:49-0:51, compared with findings for the posterior in Adams et al (2004) (0.44), which used similar stimuli.…”

Demonstration of cue recruitment: Change in visual appearance by means of Pavlovian conditioning

“…Experience with a visual scene can systematically bias how shading cues are used to infer the shapes of new 3D objects in the scene (48). Y 3D interpretations of images.…”

Crossmodal correspondences between odors and contingent features: odors, musical notes, and geometrical shapes

“…Although it is not often highlighted in the literature, the latter fact is crucial to olfaction: Smelling a perfume is often done with the bottle held below the nostrils, grounding a perception (then helped by tactile, proprioceptive, and visual cues) of smells as also coming from below. More generally, and even if odors are not phenomenologically experienced as coming from below, humans have certainly evolved with a "natural constraint" to expect smells to come from the ground, as they expect, for instance, the illuminant to come from above (Adams, Graf, & Ernst, 2004). The persistent notes that are experienced first are progressively complemented by other notes, also emanating from below-thus perhaps encouraging the impression that smells "pile up" in the nose, with first notes being "pushed up" when new notes also come from below.…”