Sensation and Perception Overview

Sensation and Perception

• 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.
• Top-Down Processing: Information processing guided by high-level mental processes, as we construct perceptions drawing on our experiences and expectations.
• Bottom-Up Processing: Analysis that begins with sensory receptors and works up to the brain's integration of sensory information.

Specific Senses: Vision

• Psychophysics: The study of relationships between the physical characteristics of stimuli (e.g., intensity) and our psychological experience of them.
• Absolute Threshold: The minimum stimulation needed to detect a particular stimulus 50% of the time.
• Signal Detection Theory: Predicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise).
• Subliminal Stimulation: Stimulation that is below one's absolute threshold for conscious awareness.
• Difference Threshold: The minimum difference between two stimuli required for detection 50% of the time.
• Weber's Law: For two stimuli to be perceived as different, they must differ by a constant minimum percentage.
• Sensory Adaptation: Diminished sensitivity as a consequence of constant stimulation.
• Transduction: Conversion of one form of energy into another.
• Electromagnetic Spectrum: Range of wavelengths that exist (from gamma rays to radio waves).
• Wavelength: Distance from peak to peak of a light or sound wave.
• Hue: The color we experience, determined by the wavelength of light.
• Intensity: Amount of energy in a light or sound wave.
• Amplitude: Height of a wave.
• Cornea: Transparent outer layer through which light enters the eye, protecting the eye while bending light.
• Pupil: Adjustable opening in the eye where light passes through.
• Iris: Colored muscle tissue surrounding the pupil that controls the pupil's size.
• Lens: Transparent structure behind the pupil that changes shape (accommodation) to focus images on the retina.
• Accommodation (Vision): Eye's lens changes shape to focus near or far objects on the retina.
• Retina: Light-sensitive inner surface of the eye that begins the visual process.
• Acuity: Sharpness of vision.
• Nearsightedness: Distant objects focus in front of the retina.
• Farsightedness: Nearby objects focus behind the retina.
• Rods: Retinal receptors detecting black, white, and gray, and night vision.
• Cones: Retinal receptors concentrated in the fovea, detecting fine details and color vision.
• Bipolar Cells: Activated when rods and cones undergo chemical changes.
• Ganglion Cells: Receive signals from bipolar cells.
• Optic Nerve: Carries neural impulses from the eye to the brain.
• Fovea: Central focal point in the retina where cones cluster for acute vision.
• Feature Detection: Nerve cells in the brain responding to specific stimulus features.
• Parallel Processing: Doing several things at once.
• Blindsight: Visual perception capacity despite reported blindness in a portion of vision.
• Trichromatic Theory: Retina contains three color receptors (red, green, blue) to produce any color.
• Subtracted Color Mixing: Removing wavelengths from reflected light (red, blue, yellow).
• Additive Color Mixing: Combining wavelengths to increase light (red, blue, green).
• Color Blindness: Absence of functioning red or green (or both) cones.
• Afterimage: Perception of a complementary color after staring at a specific color.
• Opponent-Process Theory: Opposing retinal processes (red-green, yellow-blue, white-black) enabling color vision.
• Blind Spot: Point where the optic nerve leaves the eye, lacking receptor cells.
• Visual Cliff: Used in depth perception studies.

Specific Senses: Hearing

• Amplitude: Loudness/strength of sound waves.
• Frequency: Number of complete wavelengths passing a point in a given time.
• Pitch: Tone's experienced highness or lowness, dependent on frequency.
• Decibels: Measurement unit for sound energy.
• Outer Ear: Channels sound waves to the eardrum.
• Eardrum: Vibrates with incoming sound waves.
• Middle Ear: Chamber containing three tiny bones (hammer, anvil, stirrup) amplifying sound.
• Cochlea: Bony, fluid-filled tube in the inner ear containing hair cells that vibrate with sound.
• Oval Window: Membrane that vibrates and jostles the cochlea's fluid.
• Inner Ear: Includes the cochlea, semicircular canals, and vestibular sacs.
• Basilar Membrane: Membrane in cochlea where sound ripples cause hair cell movement.
• Hair Cells: Tiny projections on the basilar membrane that trigger nerve impulses.
• Place Theory: Links pitch with the location of the basilar membrane stimulation (high-pitched sounds).
• Frequency Theory: Nerve impulses matching the frequency of a stimulus determine pitch (low-pitched sounds).
• Conduction Hearing Loss: Damage to the mechanical system of sound conduction to the cochlea.
• Sensorineural Hearing Loss: Damage to the cochlea's receptor cells or auditory nerves.
• Cochlear Implant: Device converting sounds into electrical signals to stimulate the auditory nerve.

Other Senses

• Pain: Biological alarm system.
• Tinnitus: Ringing in the ears.
• Gate-Control Theory: Spinal cord's neurological "gate" that blocks or allows pain signals to reach the brain.
• Taste Sensations: Sweet, sour, salty, bitter, umami.
• Chemical Senses: Taste and smell.
• Sensory Interaction: One sense influencing another.
• Olfactory Receptor Cells: Detect odor molecules in the nasal cavity.
• Kinesthesis: Sense of body position and movement.
• Vestibular Sense: Sense of body movement and position, including balance.
• Vestibular Sacs: Fluid-filled structures connecting to the cochlea responding to head movement.
• Selective Attention: Focusing conscious awareness on a particular stimulus.
• Cocktail Party Effect: Ability to attend to relevant stimuli.

Perceptual Organization

• Gestalt: Organized whole.
• Figure-Ground: Organization of visual field into objects (figures) and their surroundings (ground).
• Grouping: Perceptual tendency to organize stimuli into coherent groups.
• Proximity: Grouping nearby figures together.
• Similarity: Grouping similar figures together.
• Continuity: Perceiving smooth, continuous patterns over discontinuous ones.
• Connectedness: Grouping linked and uniform patterns together.
• Closure: Filling gaps to create a complete, whole object.

Depth Perception

• Depth Perception: Ability to see objects in three dimensions even though images strike the retina as two dimensional.
• Visual Cliff: Experiment to test depth perception in infants and young adults.
• Binocular Cues: Depth cues requiring the use of two eyes (nearby objects).
• Retinal Disparity: Comparing images from two eyes to compute distance.
• Convergence: Eyes turning inward to view nearby objects.
• Monocular Cues: Depth cues available to either eye alone (far objects).
• Relative Size: Assuming similar-sized objects, the smaller retinal image suggests a farther object.
• Interposition: One object blocking the view of another, suggesting a closer object.
• Relative Clarity: Hazy objects seem farther than sharp objects.
• Texture Gradient: A distinct surface texture becoming less distinct with distance.
• Relative Height: Objects higher in the visual field seem farther away.
• Relative Motion (Motion Parallax): Moving objects appear to move faster those farther away.
• Linear Perspective: Parallel lines appear to converge with distance.
• Light and Shadow: Nearby objects reflect more light.
• Motion Parallax: Apparent movement of objects as we move.
• Phi Phenomenon: Illusion of movement created when two or more adjacent lights blink on and off in quick succession.

Perceptual Constancy

• Perceptual Constancy: Perceiving objects as unchanging (consistent in lightness, color, shape, size) even as illumination and retinal images change.
• Relative Luminance: Amount of light an object reflects relative to its surroundings.
• Perceptual Adaptation: Adjustment to an artificially displaced or inverted visual field.
• Perceptual Set: Mental predisposition to perceive one thing and not another.

Extrasensory Perception (ESP) and Parapsychology

• ESP: Controversial claim of perception without sensory input.
• Parapsychology: Study of paranormal phenomena (ESP and psychokinesis).
• Telepathy: Mind-to-mind communication (ESP).
• Clairvoyance: Perceiving remote events (ESP).
• Precognition: Perceiving future events (ESP).
• Psychokinesis: Moving objects with the mind (ESP).

Pain

• Large Nerve Fibers: Often close the pain gate.
• Small Nerve Fibers: Often open the pain gate.

Explore the key concepts of sensation and perception in this quiz. Delve into top-down and bottom-up processing, as well as the role of psychophysics in understanding our sensory experiences. Test your knowledge on how we perceive stimuli from our environment.