AP Psych Unit 1.6 - Sensations

Sensation

Sensation

The process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment.

Bottom-up processing

Analysis that begins with sensory receptors and works up to the brain’s integration of sensory information.

Transduction

Conversion of one form of energy into another; transforming stimulus energies into neural impulses that the brain can interpret.

Absolute threshold

The minimum stimulus energy needed to detect a particular stimulus 50% of the time.

Signal Detection Theory

A theory predicting how and when we detect the presence of a faint stimulus amid background stimulation, depending on experience, expectations, motivations, and awareness.

Sensory adaptation

Diminished sensitivity as a consequence of constant stimulation; becoming less aware of an unchanging stimulus.

Just-noticeable difference (or difference threshold)

The minimum difference between two stimuli required for detection 50% of the time.

Weber’s law

To be perceived as different, two stimuli must differ by a minimum percentage, rather than a constant amount.

Sensory interaction

The interaction of the senses with one another and how they influence each other.

Synesthesia

The stimulation of one sense results in the activation of other senses, such as perceiving sounds as colors.

Retina

The light-sensitive inner surface of the eye that contains receptor rods and cones plus layers of neurons for processing visual information.

Fovea

The central focal point on the retina where the eye’s cones cluster.

Photoreceptors

Cells that convert light energy into neural impulses forwarded to the brain, reassembling them into an image.

Rods

Retinal receptors that detect black, white, and gray and are sensitive to movement, necessary for peripheral vision.

Cones

Retinal receptors concentrated near the center of the retina that function in daylight and detect fine detail and color.

Ganglion cells

Cells activated by bipolar cells whose axons come together to form the optic nerve.

Blindspot

The point at which the optic nerve leaves the eye, creating a blind spot due to no receptor cells present.

Optic nerve

The nerve that carries neural impulses from the eye to the brain.

Lens

The transparent structure behind the pupil that changes shape to help focus images on the retina.

Accommodation

The process by which the eye’s lens changes shape to focus near or far objects on the retina.

Nearsightedness

Blurred vision when visual images are focused in front of the retina, rather than directly on it.

Farsightedness

Seeing faraway objects clearly; caused by visual imaging being focused behind the retina.

Wavelength

The distance from the peak of one light or sound wave to the peak of the next, influencing color perception.

Trichromatic theory

The theory that the retina contains three different types of color receptors sensitive to blue, green, and red.

Opponent-process theory

A theory that opposing retinal processes enable color vision through stimulation and inhibition of color perception.

Afterimages

Visual perception of an image after the stimulus is no longer present; can be positive or negative.

Dichromatism

A type of color blindness where a person cannot see a certain set of two colors, usually red/green or yellow/blue.

Monochromatism

A condition where a person cannot see any color and only perceives the world in black and white.

Prosopagnosia

A condition where individuals are unable to recognize faces despite being able to see individual body parts.

Blindsight

A condition in which a person can respond to a visual stimulus without consciously experiencing it.