Chapter 3: Sensation and Perception

Psyc 1100

Sensation

The process of detecting and transmitting stimulus energies from the environment to the brain through sensory receptors.

Perception

The process of organizing and interpreting sensory information so that it makes sense.

Bottom-up processing

Processing of sensory input that begins with external stimuli and moves up to the brain for analysis.

Top-down processing

Processing based on prior knowledge

Sensory receptors

Specialized cells that detect and transmit sensory information to the brain.

Photoreception

The sensory detection of light

Mechanoreception

The detection of pressure

Chemoreception

The detection of chemical stimuli

Absolute threshold

The minimum amount of stimulus energy required for an organism to detect a stimulus.

Difference threshold

The minimum difference between two stimuli that can be detected

Weber's Law

The principle that the JND is a constant proportion of the original stimulus.

Signal detection theory

A theory that explains how we detect stimuli under conditions of uncertainty

Perceptual set

A predisposition to perceive something in a particular way

Sensory adaptation

A reduction in sensitivity to a constant stimulus over time.

Cornea

The clear

Iris

The colored part of the eye that controls the size of the pupil and the amount of light entering the eye.

Pupil

The opening in the center of the iris that regulates the amount of light entering the eye.

Lens

The transparent structure behind the pupil that focuses light on the retina.

Retina

The light-sensitive layer at the back of the eye where photoreceptors (rods and cones) are located.

Fovea

The central focal point in the retina

Optic nerve

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

Rods

Photoreceptors in the retina sensitive to low light levels

Cones

Photoreceptors in the retina that detect color and are responsible for high-acuity vision.

Visual cortex

The area of the brain where visual information is processed.

Feature detectors

Neurons in the visual cortex that respond to specific features of a stimulus

Trichromatic theory

A theory of color vision that suggests three types of cones are sensitive to red

Opponent-process theory

A theory of color vision that suggests colors are perceived in opposing pairs

Gestalt psychology

A psychological approach that emphasizes that the whole of perception is greater than the sum of its parts.

Figure-ground relationship

A Gestalt principle where we perceive objects (figures) as distinct from their background (ground).

Closure

A Gestalt principle where we mentally fill in gaps to perceive incomplete figures as complete.

Proximity

A Gestalt principle that states objects close to each other are perceived as a group.

Similarity

A Gestalt principle that states objects similar in appearance are perceived as a group.

Perceptual constancy

The perception that objects remain constant and unchanging despite changes in sensory input.

Depth perception

The ability to perceive objects in three dimensions and judge distance.

Binocular cues

Cues for depth perception that involve the use of both eyes

Monocular cues

Cues for depth perception that involve only one eye

Cochlea

A spiral-shaped structure in the inner ear responsible for converting sound vibrations into neural signals.

Auditory nerve

The nerve that carries sound information from the cochlea to the brain.

Vestibular sense

The sense responsible for balance and spatial orientation

Kinesthetic sense

The sense of body movement and position

Weber’s Law

The concept that the just noticeable difference (JND) is proportional to the intensity of the stimulus.