Ap Psychology Sensation and Perception

Psychophysics

The branch of psychology that studies how physical stimuli (sensations) translate to psychological experiences (perceptions)

Sensation

The process of detecting information from the environment via the sensory organs

Perception

The complementary process to sensation, which involves the cognitive processes of organizing and interpreting sensations in the brain

Transduction

The conversion of stimuli received from the environment by specialized cells in sensory organs into neural messages

Absolute Threshold

The minimum intensity of stimulation needed for detection 50% of the time

Difference Threshold (Just-Noticeable Threshold)

The smallest amount of change in or between stimuli that can be detected 50% of the time

Weber’s Law

The minimum change needed to create a JND is a constant percentage of the original stimulus

Sensory Adaptation

The reduced responsiveness in sensory receptor cells due to constant or prolonged exposure to a stimulus

Sensory Interaction

The sensory systems working together to influence how we perceive the world

Synthesia

A condition in which one sensory system generates automatic and consistent sensations in another sensory system

Wavelength

The physical property of a light wave that determines color

Amplitude

The physical property of a light wave that determines brightness

Retina

A photosensitive layer located at the back of the eye containing two types of photoreceptor cells

Cones

Photoreceptors mainly located in the retina’s center responsible for detecting stimuli under bright light conditions and providing information about color and detail

Fovea

A small central region of the retina where visual acuity is the sharpest because it has the most cones

Rods

Photoreceptors mainly located on the outer edge of periphery of the retina that are responsible for detecting stimuli under low light conditions

Bipolar cell

A retinal cell that connects a photoreceptor and a ganglion cell

Ganglion cell

A retinal cell that receives information from bipolar cells. The axons of these cells combine to form the optic nerve

Blind Spot

The gap within the visual field created by the lack of photoreceptor cells in the optic disc, which is the area on the retina where the optic nerve exists the eye

Visual Transduction

The process of converting light waves received by sensory receptor cells into neural messages that can be interpreted by the brain

Accommodation

The process in which the lens in the eye bends to direct light waves onto the retina

Light Adaption

The processes that occur in the eye that make it easier to see under bright conditions

Dark Adaptation

The processes that occur in the eye that make it easier to see under low light conditions

Trichromatic Theory

The theory that the brain perceives color based on information from three types of cones in the retina

Opponent-process Theory

The theory that the brain perceives color based on information from three pairs of opponent neurons that work together, One half of the opponent pair is inhibited by the other half, which is activated.

Dichromatism

A type of color vision deficiency that results when there are only two types of cones instead of three

Color Vision Deficiency

A genetic condition on the X chromosome related to damaged or missing cones. It is more common in males.

Monochromatism

A type of color vision deficiency that results when there is only one type of cone instead of three

Nearsightedness

A condition that occurs when the eyeball is longer than normal, and the lens focuses the image in front of the retina resulting in reduced sharpness of vision for far-away objects

Farsightedness

A condition that occurs when the eyeball is shorter than normal, and the lens focuses the image behind the retina resulting in decreased sharpness of vision for close objects

Prosopagnosia

A condition that makes recognizing and perceiving faces difficult

Blindsight

A condition in which individuals with damage to their visual cortex can still sense and sometimes locate visual stimuli in their blind visual field

Bottom-up Processing

The method by which the brain builds a perception based on external sensory information

Top-down Processing

The method by which the brain builds a perception based on internal prior expectations

Hue

The color experienced

Lens

Transparent structure behind pupil that changes shape to focus images on the retina

Pupil

Adjustable opening in the center of the eye

Iris

A ring of muscle that forms the colored portion of the eye around the pupil and controls the size of the pupil opening

Cornea

Transparent outer covering of the eye

Parallel Processing

The name for how the brain processes color movement, form, and depth simultaneously in different areas

Reception

The stimulation of sensory receptor cells by energy

Transmission

Delivering this neural information to the brain to be processed