Section 3: Sensation and Perception Psychology in Modules by Saul Kassin

©2006 Prentice Hall Sensation and Perception Measuring the Sensory Experience Sensation Perception Extrasensory Perception

©2006 Prentice Hall §Sensation l The processes by which our sense organs receive information from the environment. §Transduction l The process by which physical energy is converted into sensory neural impulses. §Perception l The processes by which people select, organize, and interpret sensations. Sensation and Perception

©2006 Prentice Hall Sensation & Perception Processes

©2006 Prentice Hall §Psychophysics l The study of the relationship between physical stimulation and subjective sensations. §Signal-Detection Theory l The theory that detecting a stimulus is jointly determined by the signal and the subject’s response criterion. Measuring Sensory Experience Research and Theory

©2006 Prentice Hall §Absolute Threshold l The smallest amount of stimulation that can be detected. §Just Noticeable Difference (JND) l The smallest amount of change in a stimulus that can be detected. Measuring Sensory Experience Thresholds

©2006 Prentice Hall §Vision: A single candle flame from 30 miles on a dark, clear night §Hearing: The tick of a watch from 20 feet in total quiet §Smell: 1 drop of perfume in a 6-room apartment §Taste: 1 teaspoon sugar in 2 gallons of water §Touch: The wing of a bee on your cheek, dropped from 1 cm Measuring Sensory Experience Absolute Sensory Thresholds

©2006 Prentice Hall §Vision §Hearing §Other Senses §Keeping the Signals Straight Sensation

©2006 Prentice Hall Vision The Electromagnetic Spectrum

©2006 Prentice Hall Vision Structures of the Human Eye

©2006 Prentice Hall §Cornea l Clear outer membrane that bends light to focus it in the eye. §Pupil l The hole in the iris through which light passes. §Lens l The structure that focuses light on the retina. Vision Structures of the Human Eye

©2006 Prentice Hall The rear of the eye where rods and cones convert light into neural impulses. Vision The Retina

©2006 Prentice Hall §Optic Nerve Pathway that carries visual information from the eyeball to the brain. Vision Visual Pathways

©2006 Prentice Hall §Some cells in the visual cortex respond only to certain types of visual information, for example, a diagonal line moving up and down. §These cells are called feature detectors. Vision Hubel & Wiesel’s Experiment

©2006 Prentice Hall §T. Young (1802) & H. von Helmholtz (1852) both proposed that the eye detects 3 primary colors: red, blue, & green. §All other colors can be derived by combining these three. Vision Trichromatic Theory

©2006 Prentice Hall Vision Afterimage

©2006 Prentice Hall

§Spectral colors vary from violet-blue to red l 470 to 700 nanometer wavelength §Opponent colors are directly across from each other on the wheel. Vision The Color Wheel

©2006 Prentice Hall Vision Test of Color Deficiency

©2006 Prentice Hall l Color vision is derived from three pairs of opposing receptors. The opponent colors are blue and yellow, red and green, and black and white. §Theory explains afterimages and color deficiency. Vision Opponent-Process Theory

©2006 Prentice Hall Audition The sense of hearing Hearing The Human Ear

©2006 Prentice Hall l The ability to judge from which direction a sound is coming §Sounds from different directions are not identical as they arrive at left and right ears. §The brain calculates a sound’s location by using differences in timing and intensity. Hearing Auditory Localization

©2006 Prentice Hall §Conduction Hearing Loss l Caused by damage to the eardrum or bones in the middle ear. §Sensorineural Hearing Loss l Caused by damage to the structures of the inner ear. Hearing Hearing Disabilities

©2006 Prentice Hall Hearing Common Sounds and the Noise They Produce

©2006 Prentice Hall Structures responsible for the sense of smell Other Senses Olfactory System

©2006 Prentice Hall l Nets of taste-receptor cells §This is a photograph of tongue surface (top), magnified 75 times. §10,000 taste buds line the tongue and mouth. §Children have more taste buds than adults do. §There are four primary tastes: sweet, salty, sour, and bitter. Other Senses Taste Buds

©2006 Prentice Hall Other Senses Sensitivity to Touch

©2006 Prentice Hall Temperature §When a person grasps two braided water pipes – one with cold water running through it and one with warm water – the sensation is “burning hot” and painful. §There are two separate pathways for warmth and cold. Other Senses The Thermal Grill

©2006 Prentice Hall Pain §Gate-control Theory l Theory that the spinal cord contains a neurological “gate”that blocks pain signals for the brain when flooded by competing signals. §Psychological control l Mind over sensation, distraction Other Senses

©2006 Prentice Hall Coordination §Kinesthetic System l Structures distributed throughout body that sense position and movement of body parts. §Vestibular System l The inner ear and brain structures that afford a sense of equilibrium. Other Senses

©2006 Prentice Hall §Synesthesia l Rare condition in which stimulation in one sensory modality triggers sensations in another sensory modality. §Each sensory system designed to operate separately from the others. §Sensory Adaptation l A decline in sensitivity to a stimulus as a result of constant exposure. Keeping the Signals Straight

§Perceptual Organization §Perceptual Constancies §Depth and Dimension §Perceptual Set §The World of Illusions Perception

©2006 Prentice Hall l Drawings that one can perceive in different ways by reversing figure and ground. §Gestalt Psychology l School of thought rooted in the idea that the whole is different from the sum of its parts. Perceptual Organization Reversible Figures

©2006 Prentice Hall §Proximity l Seeing 3 pair of lines in A §Similarity l Seeing columns of orange and red dots in B §Continuity l Seeing lines that connect 1 to 2 and 3 to 4 in C §Closure l Seeing a horse in D Perceptual Organization Gestalt Laws of Grouping

©2006 Prentice Hall §Geons (geometric icons) are simple 3D component shapes. §A limited number are stored in memory. §Geons are combined to identify essential contours of objects. Perceptual Organization Identifying Objects

©2006 Prentice Hall §Size Constancy l The tendency to view an object as constant in size despite changes in the size of the retinal image. §Shape Constancy l The tendency to see an object as keeping its form despite changes in orientation. Perceptual Constancies

©2006 Prentice Hall Perceptual Constancies The Ames Room §A specially-built room that makes people seem to change size as they move around in it §The room is not a rectangle, as viewers assume it is. §A single peephole prevents using binocular depth cues.

©2006 Prentice Hall §Even though these images cast shadows of different shapes, they still are seen as round. Perceptual Constancies Shape Constancy

©2006 Prentice Hall §Depth Perception l The use of visual cues to estimate depth and distance. §Convergence l A binocular cue involving the turning inward of the eyes as an object gets closer. §Binocular Disparity l A binocular cue whereby the closer an object is, the more different the image is in each retina. Depth and Dimension

©2006 Prentice Hall l Distance cues that enable the perception of depth with one eye. Relative Image Size Texture Gradient Linear Perspective Interposition Atmospheric Perspective Relative Elevation Familiarity Depth and Dimension Monocular Depth Cues

©2006 Prentice Hall §Devised by Eleanor Gibson and Richard Walk to test depth perception in infants and animals. §Provides visual illusion of a cliff. §Caregiver stands across the gap. §Babies are not afraid until about the age they can crawl. Depth and Dimension The Visual Cliff

©2006 Prentice Hall §What is seen in the center figures depends on the order in which one looks at the figures: l If scanned from the left, a man’s face is seen. l If scanned from the right, a woman’s figure is seen. Perceptual Set

©2006 Prentice Hall §The same physical stimulus can be interpreted differently depending on perceptual set, e.g., context effects. §When is the middle character the letter B and when is it the number 13? Perceptual Set Context Effects

©2006 Prentice Hall l Illusion in which the perceived length of a line is altered by the position of other lines that enclose it The World of Illusions The Müller-Lyer Illusion

©2006 Prentice Hall l Illusion in which the perceived line length is affected by linear perspective cues. §Side lines seem to converge §Top line seems farther away l But the retinal images of the red lines are equal. The World of Illusions The Ponzo Illusion

§The Case for ESP §The Case against ESP §The Continuing Controversy Extrasensory Perception

©2006 Prentice Hall §Extrasensory Perception (ESP) l The ability to perceive something without ordinary sensory information. l This has not been scientifically demonstrated. §Parapsychologists distinguish between three types of ESP: l Telepathy – Mind-to-mind communication l Clairvoyance – Perception of remote events l Precognition – Ability to see future events The Case for ESP

©2006 Prentice Hall §J. B. Rhine conducted many experiments on ESP using stimuli such as these. §Rhine believed that his evidence supported the existence of ESP, but his findings were flawed.. The Case against ESP ESP Cards

©2006 Prentice Hall §The ganzfield procedure §Researchers disagree about the reliability of studies done to replicate the ganzfield test. §Visit for information about the James Randi Educational Foundation’s million-dollar paranormal challenge. The Continuing Controversy