Psychology Chapter: Sensation and Perception

Key Terms and Definitions

• Sensation: Process of receiving and representing stimulus energies through sensory receptors and the nervous system.
• Perception: Organizing and interpreting sensory information, allowing recognition of meaningful objects and events.
• Bottom-up processing: Analysis that starts with sensory receptors and builds up to the integration of sensory information in the brain.
• Top-down processing: Higher-level mental processes guide information processing, constructing perceptions based on experience and expectations.

Psychophysics and Sensory Thresholds

• Psychophysics: Study of the relationship between physical stimuli and psychological experiences.
• Absolute threshold: Minimum stimulation needed to detect a stimulus 50% of the time.
• Signal detection theory: Predicts how and when we detect faint stimuli amidst background noise, focusing on brief stored information.
• Difference threshold: Minimum difference necessary between two stimuli for detection 50% of the time known as just noticeable difference (JND).

Visual Processing

• Subliminal sensation: Detection of stimuli below the absolute threshold.
• Weber's law: To be perceived as different, two stimuli must differ by a constant minimum percentage.
• Sensory adaptation: Reduced sensitivity due to constant stimulation.

The Eye and Visual System

• Transduction: Conversion of one form of energy into another, transforming stimulus into neural impulses.
• Wavelength: Distance between peaks of waves; influences color perception.
• Amplitude: Height of a wave; affects brightness in visuals and volume in sound.
• Pupil: Adjustable opening in the center of the eye that lets light in.
• Iris: Muscle tissue that controls pupil size and gives eyes their color.
• Lens: Transparent structure behind the pupil that focuses images on the retina.
• Accommodation: Process in which the lens changes shape to focus on objects at different distances.
• Retina: Inner light-sensitive layer of the eye that begins processing visual information.

Vision and Eye Conditions

• Acuity: Sharpness of vision.
• Nearsightedness: Difficulty seeing distant objects clearly; image focuses in front of the retina.
• Farsightedness: Difficulty seeing nearby objects clearly; image focuses behind the retina.
• Rods: Receptors for black, white, and gray; essential for peripheral and twilight vision.
• Cones: Detect fine details and colors, concentrated in the center of the retina.
• Optic nerve: Carries neural impulses from the eye to the brain.
• Blind spot: Area where the optic nerve exits the eye; lacks receptor cells.
• Fovea: Central point in the retina where cones are clustered for sharp vision.

Color Vision Theories

• Young-Helmholtz Trichromatic theory: Retina contains three types of color receptors sensitive to red, green, and blue.
• Opponent-Process theory: Opposing retinal processes enable color vision, explaining after-images.

Sound Perception

• Audition: Sense of hearing.
• Frequency: Number of complete wavelengths passing a point in a given time.
• Pitch: Perception related to the frequency of sound waves.
• Cochlea: Fluid-filled tube in the inner ear where sound waves trigger nerve impulses.

Hearing Mechanisms

• Place theory: Links pitch perception with the location of stimulation in the cochlea.
• Frequency theory: Rate of nerve impulses matches the frequency of a tone to determine pitch.
• Conduction hearing loss: Damage to the mechanical system conducting sound waves.
• Sensorineural hearing loss: Damage to the cochlea's receptor cells or auditory nerves.

Pain Perception

• Gate-Control theory: Spinal cord contains a "gate" that either blocks or allows pain signals to reach the brain.

Sensory Integration and Special Senses

• Sensory interaction: One sense influencing another, e.g., smell enhancing taste.
• Kinesthesis: Sensing the position and movement of body parts through proprioceptors.
• Vestibular sense: Sense of body movement and balance, informed by inner ear structures.

Gestalt Principles

• Gestalt psychology: Perception of whole forms rather than individual components.
• Figure-ground: Organization of visual fields into objects that stand out from their backgrounds.
• Grouping: Tendency to organize stimuli into coherent groups based on principles like proximity, similarity, continuity, and closure.

Depth Perception and Cues

• Depth perception: Ability to see objects in three dimensions and judge distance.
• Binocular cues: Require input from both eyes for depth perception.
• Monocular cues: Require input from one eye, useful for understanding depth in two-dimensional art.

Perceptual Phenomena

• Perceptual constancy: Recognizing objects as stable despite changes in illumination.
• Perceptual set: Mental predisposition to perceive stimuli in a certain way, influenced by prior experience.

Extrasensory Perception

• Extrasensory perception (ESP): Perception occurring apart from sensory input, including phenomena like telepathy and clairvoyance.
• Parapsychology: Study of paranormal phenomena, including ESP.

Summary of Individual and Collective Perception

• Visual capture: When vision dominates over other sensory inputs.
• Synaesthesia: Merging of senses, such as seeing colors when hearing sounds.
• Cocktail party effect: Selective attention to one voice among many, demonstrating focus on specific stimuli.

Test your knowledge on key terms and concepts related to sensation and perception in psychology. This quiz covers essential definitions, psychophysics, and sensory thresholds, helping you understand how we interpret stimuli in our environment.