sensation and perception vocab list

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

Perception: The process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.

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

Top-down Processing: Information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations.

Transduction: The conversion of one form of energy into another, such as the transformation of stimulus energy (e.g., light or sound) into neural impulses the brain can interpret.

Psychophysics: The study of the relationship between physical characteristics of stimuli (e.g., intensity) and our psychological experience of them.

Thresholds

Absolute Threshold: The minimum stimulation needed to detect a particular stimulus 50% of the time.

Difference Threshold (Just Noticeable Difference - JND): The smallest difference between two stimuli that a person can detect 50% of the time.

Weber’s Law: The principle that the size of the just noticeable difference is a constant proportion of the original stimulus intensity.

Signal Detection Theory: A theory predicting how and when we detect the presence of a faint stimulus (signal) amid background noise (other stimuli). It assumes that there is no single absolute threshold and that detection depends on experience, expectations, motivation, and alertness.

Subliminal: Below the threshold of conscious awareness; stimuli that are detected less than 50% of the time.

Sensory Systems

Sensory Adaptation: Diminished sensitivity as a consequence of constant stimulation.

Selective Attention: The focusing of conscious awareness on a particular stimulus while ignoring others.

Feature Detectors: Nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement.

Sensory Receptors: Specialized cells responsible for converting external stimuli into neural signals (e.g., photoreceptors in the eye).

Vision

Light: Electromagnetic energy that is visible to the human eye.

Wavelength: The distance from the peak of one light wave to the peak of the next, determining the color we perceive (e.g., blue light has a short wavelength).

Hue: The color of light; determined by the wavelength of the light.

Intensity: The amount of energy in light waves, determined by the wave’s amplitude, which influences brightness.

Pupil: The adjustable opening in the center of the eye through which light enters.

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

Retina: The light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information.

Rods: Retinal receptors that detect black, white, and gray, and are responsible for peripheral and night vision.

Cones: Retinal receptors that are concentrated near the center of the retina (fovea) and that function in daylight or in well-lit conditions; they detect fine detail and color.

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

Fovea: The central focal point in the retina, around which the eye’s cones cluster.

Blind Spot: The point at which the optic nerve leaves the eye, creating a “blind” spot because no receptor cells are located there.

Hearing (Audition)

Sound Waves: Waves of air pressure that cause the sensation of sound.

Frequency: The number of complete wavelengths that pass a point in a given time (e.g., per second). Frequency determines pitch.

Pitch: A tone’s experienced highness or lowness, depending on the frequency of the sound wave.

Amplitude: The height of a wave, which determines the loudness of the sound.

Eardrum (Tympanic Membrane): A thin membrane that vibrates when sound waves hit it, transferring sound vibrations to the middle ear.

Ossicles: The three tiny bones in the middle ear (hammer, anvil, stirrup) that amplify sound vibrations.

Cochlea: A coiled, bony, fluid-filled tube in the inner ear that transforms sound vibrations into neural messages.

Basilar Membrane: A membrane in the cochlea that contains hair cells, which are sensory receptors for sound.

Auditory Nerve: The nerve that carries neural impulses from the cochlea to the brain.

Perception

Perceptual Set: A mental predisposition to perceive one thing and not another.

Gestalt: An organized whole. Gestalt psychologists emphasized that the whole is greater than the sum of its parts.

Figure-Ground: The organization of the visual field into objects (figures) that stand out from their surroundings (the ground).

Proximity: A Gestalt principle that states that we group nearby figures together.

Similarity: A Gestalt principle that states that we group similar figures together.

Continuity: A Gestalt principle that states that we perceive smooth, continuous patterns rather than discontinuous ones.

Closure: A Gestalt principle that states that we fill in gaps to create a complete, whole object.

Depth Perception

Depth Perception: The ability to see objects in three dimensions and judge distance.

Binocular Cues: Depth cues that depend on the use of two eyes, such as retinal disparity and convergence.

Retinal Disparity: A binocular cue for perceiving depth; by comparing images from the two eyes, the brain computes distance.

Convergence: A binocular cue for perceiving depth; the extent to which the eyes converge inward when looking at an object.

Monocular Cues: Depth cues available to either eye alone, such as relative size, interposition, and linear perspective.

Relative Size: A monocular cue that allows us to judge the size of an object based on its distance from us.

Linear Perspective: A monocular cue that shows parallel lines appear to converge as they get farther away.

Motion and Perception

Motion Parallax: A monocular cue for depth perception in which closer objects appear to move faster than objects that are farther away.

Perceptual Constancy: Perceiving objects as unchanging even as illumination and retinal images change.

Size Constancy: The perception that an object’s size remains constant despite changes in its distance from us.

Color Constancy: The perception that the color of an object remains consistent even if the lighting changes.

Shape Constancy: The perception that an object maintains its shape despite changes in the angle of view.

Other Sensory Systems

Kinesthetic Sense: The sense of the position and movement of the body parts.

Vestibular Sense: The sense of balance and spatial orientation, controlled by the inner ear’s semicircular canals.

Olfaction (Smell): The sense of smell, which is processed by the olfactory receptors in the nose.

Gustation (Taste): The sense of taste, which detects sweet, sour, salty, bitter, and umami flavors through receptors on the tongue.