Visual Receptors and Color Vision Theories

Study Notes

Visual Receptors

Rods are responsible for vision in low light conditions and are primarily located in the periphery of the retina.
Cones are responsible for color vision and detail, are concentrated in the fovea.

Theories of Colour Vision

Trichromatic theory proposes that color perception is created by the activation ratios of three types of cones, each sensitive to a different wavelength: short, medium, and long.
Opponent-process theory posits that colors are perceived in pairs (red-green, blue-yellow, black-white), with each pair being antagonistic.
Retinex theory suggests that the cortex compares retinal data to achieve color consistency across different lighting conditions.

Visual Pathways

The dorsal pathway, also known as the "where/how" pathway, travels through the parietal cortex and is crucial for spatial awareness and movement guidance.
The ventral pathway, also known as the "what" pathway, travels through the temporal cortex and is responsible for object recognition.

Retinal Structure

The fovea has a high spatial resolution due to each receptor connecting to a single bipolar and ganglion cell.
The periphery has a low spatial resolution because multiple receptors converge onto a single bipolar and ganglion cell, which enhances light sensitivity.

Auditory Theories of Pitch Perception

Place theory proposes that different frequencies activate specific locations along the basilar membrane in the cochlea.
Frequency theory suggests that the basilar membrane vibrates at the same frequency as the sound, creating action potentials at that frequency.
Combined theory suggests that low frequencies are processed by frequency theory, while high frequencies are processed by place theory.

Sound Localization

Sound localization relies on cues such as the time of arrival differences between the ears (interaural time difference) and the intensity difference due to the head blocking sound (interaural intensity difference), creating a "sound shadow."

Visual Receptors

Rods are responsible for vision in low light conditions and are primarily located in the periphery of the retina.
Cones are responsible for color vision and detail perception, concentrated in the fovea.

Theories of Color Vision

The Trichromatic Theory proposes that three types of cones, sensitive to short, medium, and long wavelengths, work together to create our perception of color.
The Opponent-Process Theory suggests that colors are perceived in opposing pairs (red-green, blue-yellow, black-white).
The Retinex Theory explains color constancy, the ability to perceive consistent color despite varying lighting conditions, by suggesting that the cortex compares retinal data to adjust for these changes.

Visual Pathways

The Dorsal Pathway, also known as the "where/how" pathway, travels through the parietal cortex and is crucial for spatial awareness and guiding movement.
The Ventral Pathway, also known as the "what" pathway, extends through the temporal cortex and is responsible for object recognition.

Retinal Structure

The fovea, a central region of the retina, offers high spatial resolution because each receptor connects directly to a single bipolar and ganglion cell.
The periphery of the retina, with its lower spatial resolution, utilizes receptor convergence, increasing sensitivity to light.

Auditory Theories of Pitch Perception

Place Theory stipulates that different frequencies activate specific locations along the basilar membrane within the cochlea.
Frequency Theory suggests that the basilar membrane vibrates at the same frequency as the incoming sound, generating action potentials at that specific frequency.
The Combined Theory combines aspects of both theories, explaining that Place Theory governs high frequencies while Frequency Theory is more applicable to low frequencies.

Sound Localization

Humans localize sound based on two primary cues: Interaural Time Differences (ITDs) - differences in the arrival time of sound at each ear - and Interaural Intensity Differences (IIDs) - differences in sound intensity due to the head blocking sound, creating a "sound shadow".

Description

This quiz covers the essential elements of visual receptors such as rods and cones, and their functions in different light conditions. It also explores various theories of color vision, including the trichromatic, opponent-process, and retinex theories, and discusses visual pathways in the brain. Test your understanding of how we perceive color and movement!