Biopsych- 6.2

Cornea

Focuses light on the pupil

Pupil

An opening that appears as the black part of the eye, changing size with more/less light.

Iris

A series of donut-shaped bands of tissue that can contract to change the size of the pupil.

Sensitivity

The ability to detect the presence of a dimly-lit object.

Acuity

The ability to see the details of an object.

Lens

Focuses light on the retina.

Accommodation

The process by which ciliary muscles adjust the lens to focus visual images sharply on the retina.

Ciliary Muscles

Muscles surrounding the lens that adjust it for focusing.

Nearsightedness

A condition where the lens does not relax enough when looking at near objects, focusing the image before it hits the retina.

Myopia

Another term for nearsightedness.

Farsightedness

A condition where the lens does not tighten enough when looking at far objects, focusing the image too far back.

Hyperopia

Another term for farsightedness.

Binocular Focus

The coordination of both eyes to keep images in focus with one another.

Ocular Muscles

Muscles that help move the eyeball within its socket.

Depth Cues

Signals that allow us to judge how far things are away from us.

Convergence

The inward turning of the eyes when objects are close.

Neuromuscular Cues

Cues that involve muscle tension and are interpreted by the brain in terms of distance.

Binocular disparity

Difference between the images on the two retinas.

Depth perception

The ability to perceive the distance of objects based on cues such as binocular disparity.

Retina

The part of the eye where light energy is absorbed and converted into neural impulses.

Fovea

High acuity area in the center of the retina that manages distortion and interprets color information.

Cones

Photopic (daytime) vision receptors that provide high-acuity color information in good lighting.

Rods

Scotopic (nighttime) vision receptors that provide high-sensitivity, low-acuity vision in dim light.

Duplexity theory of vision

The idea that cones mediate photopic vision and rods mediate scotopic vision.

Photopic system

The visual system that utilizes cones and functions in lighted conditions.

Scotopic system

The visual system that mainly utilizes rods and functions in dim light.

Pupil accommodation

The adjustment of the pupil size to compromise between acuity and sensitivity.

Retinal layers

The multi-layered structure of the retina that includes a receptor layer, horizontal cell layer, bipolar layer, amacrine cell layer, and retinal ganglion cell layer.

Light distortion

The alteration of light as it passes through the layers of the retina before reaching the receptors.

Neural impulses

Signals generated by the receptors in the retina that are sent to the brain.

Color coding

The process by which the fovea interprets color information based on specific wavelength ranges.

High acuity

The ability to see fine detail, primarily associated with cone vision.

Low acuity

The inability to see fine detail, primarily associated with rod vision.

High sensitivity

The ability to detect light in low-light conditions, primarily associated with rod vision.

Low sensitivity

The inability to detect light in low-light conditions, primarily associated with cone vision.

Cylindrical receptors

Receptors surrounding the fovea that are called rods.

Conical shape

The shape of the receptors in the fovea, known as cones.

Light energy absorption

The process by which light is absorbed by the retina and converted into neural impulses.

Component Theory

Also known as trichromatic theory, it posits that the fovea contains receptors for three different colors.

Trichromatic theory

A theory of color perception suggesting that all colors are interpreted in terms of red, green, and blue composition.

Color blindness

A condition where one or more types of cones are dysfunctional or missing, reducing the number of distinguishable colors.

Visual transduction

The process of converting light into neural signals through the absorption of light by pigments in receptors.

Transduction

The general term for the process by which receptor cells absorb environmental energy and convert it to another form.

Neural impulse

An electrical signal that is fired back through the layers of the retina as a result of changes in ion concentration in rods and cones.

Convergent communication

A principle of duplexity theory explaining how neural impulses from rods and cones can merge, affecting sensitivity and contrast.

Spatial summation

The process by which low intensity signals can combine to create a stronger overall signal.

High-contrast image

An image characterized by a significant difference between the lightest and darkest areas, often produced by the photopic system.

Low-contrast image

An image with minimal difference between light and dark areas, typically produced by the scotopic system.

Resolution

The detail an image holds, which is higher in systems with less convergence, such as the photopic system.

Color receptors

The three types of cones in the fovea that respond to red, green, and blue wavelengths.

Photon

A particle of light that can stimulate cones in the eye, leading to color perception.

Ion concentration change

A change in the balance of ions within rods and cones that triggers the firing of a neural impulse.

Image blurring

The loss of detail in an image due to the merging of signals from multiple rods and cones during convergent communication.

High cells-per-inch resolution

The characteristic of the photopic system where there is minimal blurring of information across individual cones.

High-resolution mental representation

A mental image that has high color contrast.

Retinotopic organization

The pattern of light absorbed by the retina is communicated to the visual system in the same pattern.

Lateral inhibition

The mechanism that enhances edges and contours by exaggerating contrast between stimuli.

Contrast enhancement

The visual system's ability to help see contours and edges that separate elements of physical reality.

Mach bands

The distinct borders perceived at the edges between two stimuli due to lateral inhibition.

Opponent-Process Theory

A theory stating that there are two different classes of cells for color, each encoding two complementary colors.

Brightness cells

A class of cells that encode brightness information.

Color mixing

The process by which three receptors engage to accurately represent the properties of a photon.

Stimulus body

The area of cells within a stimulus that are laterally inhibited by surrounding cells.

Edge cells

Cells located at the boundary between two stimuli that experience less inhibition than those within the stimulus body.

Visual system

The system that processes visual information and enhances the perception of edges and colors.

Occipital lobe

The part of the brain where visual information is processed.

Neural activity

The pattern of brain activity that corresponds to visual stimuli, such as a spoked wheel.

Dim light

A type of light stimulus that is perceived differently than intense light due to lateral inhibition.

Intense light

A type of light stimulus that creates a stronger perception due to contrast enhancement.

Visual perception

The process of interpreting visual stimuli to understand the surrounding environment.

Opponent Colors

Colors that are far apart on the visible spectrum and cannot co-exist in a single photon.

Opponent Process Theory

A theory stating that certain retinal cells become more active to one color and less active to its opponent color.

Action Potentials

Electrical signals in neurons that are always followed by a refractory period.

Hyperpolarization

A state where the neuron becomes less active, leading to the perception of opposing colors in opponent process cells.

Color After-Images

Illusions of opposing colors perceived after staring at an image for an extended period.

Retinal Ganglia

Layer of cells in the retina where fired signals travel back through to enhance edges and perceive color.

Optic Nerve

The nerve that carries signals from the retinal ganglia out the back of the eye.

Blindspot

An area in the visual field with no rods or cones where the optic nerve exits the eye.

Completion

The visual system's ability to fill in the blind spot using information from surrounding cells.

Retinotopic Manner

The organization of signals traveling back through the retinal layers to enhance perception.

Sustained Hyperpolarization

A prolonged state of reduced neuron activity that leads to the perception of opposing colors.

Illusion of Opposing Colors

The perception of colors opposite to the original stimulus after prolonged viewing.

Efficient Transmission of Color Information

The process by which the visual system conveys color details effectively.

Visual Field

The entire area that can be seen when the eyes are in a fixed position.

Surrounding Signals

Information from cells around the blind spot that aids in visual completion.

Perception of Color

The brain's interpretation of color information received from the retina.

Tired Opponent Processing Cells

Cells that become less responsive after prolonged exposure to a specific color stimulus.

Visual and Perceptual Systems

The systems that work together to interpret and understand visual stimuli.

American Flag Demonstration

A simple demonstration of opponent process theory using color perception after staring at a dot.