AP Psychology Unit 4 Part 1

Trichromatic Theory

(Young-Hemholz Theory) Proposed mechanism for color vision with cones that are differentially sensitive to different wavelengths of light; each color you see results from specific ration of activation amount the three types of receptors

Stimulus

A change in the environment that can be detected by sensory receptors

Acuity

Ability to detect fine details, sharpness of vision; can be affected by small distortions in the shape of the eye

Binocular Cues

Clues about distance (requiring two eyes)

Iris

Colored muscle surrounding the pupil that regulates the size of the pupil opening

Weber's Law

Difference thresholds increase in proportion to the size of the stimulus

Dark Adaptation

Increased visual sensitivity that gradually develops when it gets dark.

Top Down Processing

Information processing guided by your preexisting knowledge or expectation to construct perceptions; is concept-driven.

Bottom Up Processing

Information processing that begins with sensory receptors and works up to the brain's integration of sensory information to construct perceptions; is data-driven

Retina

Light sensitive surface in the back of the eye containing rods and cones that transducer light energy - also has layers of bipolar cells and ganglion cells that transmit visual information to the brain

Signal Detection Theory

Maintain that minimum threshold varies with fatigue, attention, expectations, motivation, emotional distress, and from one person to another.

Difference Threshold

Minimum difference between any two stimuli that a person can detect 50% of the time

Photoreceptors

Modified neurons (rods and cones) that convert light energy to electrochemical neural impulses

Optic Nerve

Nerve formed by ganglion cell axons; carries the neural impulses from the eye to he thalamus of the brain

Just Noticeable Difference (JND)

Our experience of the difference threshold

Response Bias

Our readiness to report detection of a stimulus when we are uncertain of its presence

Rods

Photoreceptors that detect black, white, and gray and that detect movement - rods are necessary for peripheral and dim-light vision when cones do not correspond - distributed throughout the retina, except none are in the fovea

Cones

Photoreceptors that detect color and fine detail in daylight or n bright-light conditions - most concentrated at the fovea of the retina, none are in the periphery where the roads are located

Accommodation

Process of changing the curvature of the lens to focus light rays on the retina

Opponent-process

Proposed mechanism fro color vision with opposing retinal processes for red-green, yellow-blue, white-black; some retinal cells are stimulated by one pair and inhibited by the other

Visible Spectrum

Range of color (hues) perceived by humans

Subliminal Stimulation

Receiving messages that are below one's absolute threshold for conscious awareness

Blind Spot

Region of the Retina where the optic nerve leaves the eye so there are no receptor cells; creates an area with no vision

Bipolar Cells

Second layer of neurons in the retina that transmit impulses from rods and cones to ganglion cells.

Pupil

Small adjustable opening in the iris that is smaller in bright light and larger in darkness

Receptor

Specialized nerve ending; responsible for detecting specific stimuli

Lens

Structure behind the pupil that changes shape, becoming more spherical or flatter to focus incoming rays into an image on the light sensitive retina

Sensory Adaptation

Temporary decrease in sensitivity to a stimulus that occurs when stimulation is unchanging

Sensation

The process by which you detect physical energy from your environment and encode it as neural signals

Perception

The process of selecting, organizing, and interpreting sensations, enabling you to recognize meaningful objects

Attention

The set of processes by which you choose from among that various stimuli bombarding your sense at any instant, allowing some to be further processed by your senses and brain

Attention

The set of processes form which you choose among the various stimuli bombarding our sense at any instant, allowing some to be further processed by your sense and brain.

Absolute Threshold

The weakest level of a stimulus that can be correctly detected at least half the time

Ganglion Cells

Third layer of neurons in the retina, whose axons converge to form the optic nerve.

Farsighted

Too little curvature of the cornea and/or lens focuses the image behind the retina, so distant objects are seen more clearly than near objects

Nearsighted

Too much curvature of the cornea and/or lens focuses image in front of the retina so nearby objects are seen more clearly than distant objects

Cornea

Transparent, curved layer in the front of the eye that bends incoming light rays

Amplitude

height of a sound wave