Related Experiment Video
Updated: Jun 24, 2026
14:38
Creating Objects and Object Categories for Studying Perception and Perceptual Learning
Published on: November 2, 2012
Where is the light? Bayesian perceptual priors for lighting direction.
J V Stone1, I S Kerrigan, J Porrill
1Department of Psychology, University of Sheffield, Sheffield S10 2TP, UK. j.v.stone@shef.ac.uk
Proceedings. Biological Sciences
|March 28, 2009
Summary
The brain resolves ambiguity in 3D figure perception by assuming a light source direction. This study reveals individual observers have unique, but biased, priors favoring light from above left.
Area of Science:
- Visual Perception
- Computational Neuroscience
- Bayesian Inference
Background:
- Perception of 3D shapes is ambiguous due to lighting.
- The brain resolves this ambiguity by assuming a consistent light source direction.
- Bayesian models incorporate prior probabilities for light-source direction.
Purpose of the Study:
- To develop a non-parametric maximum-likelihood estimation method for determining lighting direction priors.
- To investigate individual differences in perceptual priors for light-source direction.
- To understand the implications for general perceptual prior estimation.
Main Methods:
- Non-parametric maximum-likelihood estimation.
- Analysis of prior probability distributions for lighting direction.
- Investigating observer-specific priors.
Main Results:
- Each observer possesses a distinct prior distribution for light-source direction.
- These priors have non-zero values across all directions.
- A consistent bias was observed, with a peak indicating a preference for light originating from the upper left.
Conclusions:
- The developed method effectively estimates individual lighting direction priors.
- Observer-specific priors demonstrate a general bias towards top-left lighting.
- Findings contribute to understanding the neural basis of perceptual priors in vision.
Related Concept Videos
02:16Light Acquisition
In order to produce glucose, plants need to capture sufficient light energy. Many modern plants have evolved leaves specialized for light acquisition. Leaves can be only millimeters in width or tens of meters wide, depending on the environment. Due to competition for sunlight, evolution has driven the evolution of increasingly larger leaves and taller plants, to avoid shading by their neighbors with contaminant elaboration of root architecture and mechanisms to transport water and nutrients.
01:22Photoreceptors and Visual Pathways
At the molecular level, visual signals trigger transformations in photopigment molecules, resulting in changes in the photoreceptor cell's membrane potential. The photon's energy level is denoted by its wavelength, with each specific wavelength of visible light associated with a distinct color. The spectral range of visible light, classified as electromagnetic radiation, spans from 380 to 720 nm. Electromagnetic radiation wavelengths exceeding 720 nm fall under the infrared category, whereas...
01:12Perceptual Constancy
Perceptual constancy is the ability to recognize that objects remain consistent and unchanged even when their appearance varies due to changes in sensory input. There are four main types of perceptual constancy: size constancy, shape constancy, color constancy, and brightness constancy.
Size constancy is the recognition that an object remains the same size, even when its image on the retina changes. For instance, a bus is perceived to be large enough to carry people, even if it looks tiny from...
Size constancy is the recognition that an object remains the same size, even when its image on the retina changes. For instance, a bus is perceived to be large enough to carry people, even if it looks tiny from...
01:24Vision
Vision is the result of light being detected and transduced into neural signals by the retina of the eye. This information is then further analyzed and interpreted by the brain. First, light enters the front of the eye and is focused by the cornea and lens onto the retina—a thin sheet of neural tissue lining the back of the eye. Because of refraction through the convex lens of the eye, images are projected onto the retina upside-down and reversed.
01:15Depth Perception and Spatial Vision
Depth perception is the ability to perceive objects three-dimensionally. It relies on two types of cues: binocular and monocular. Binocular cues depend on the combination of images from both eyes and how the eyes work together. Since the eyes are in slightly different positions, each eye captures a slightly different image. This disparity between images, known as binocular disparity, helps the brain interpret depth. When the brain compares these images, it determines the distance to an object.
01:21Perceiving Loudness, Pitch, and Location
The human brain perceives pitch through two primary mechanisms reflected in place theory and frequency theory. Each mechanism describes how sound waves are interpreted as specific pitches by the brain, offering insights into the intricate processes of auditory perception.
Place theory, or place coding, suggests that different pitches are heard because various sound waves activate specific locations along the cochlea's basilar membrane. The brain determines the pitch of a sound by identifying...
Place theory, or place coding, suggests that different pitches are heard because various sound waves activate specific locations along the cochlea's basilar membrane. The brain determines the pitch of a sound by identifying...