Essentials of Psychology by Saul Kassin CHAPTER 3

Essentials of Psychology, by Saul Kassin CHAPTER 3: Sensation and Perception © 2004 Prentice Hall Publishing

Sensation and Perception Measuring the Sensory Experience Sensation Perception Extrasensory Perception Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Sensation and Perception • Sensation – The processes by which our sense organs receive information from the environment. • Transduction – The process by which physical energy is converted into sensory neural impulses. • Perception – The processes by which people select, organize, and interpret sensations. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Processes of Sensation & Perception Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Measuring Sensory Experience Research and Theory • Psychophysics – The study of the relationship between physical stimulation and subjective sensations. • Signal-Detection Theory – The theory that detecting a stimulus is jointly determined by the signal and the subject’s response criterion. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Measuring Sensory Experience Thresholds • Absolute Threshold – The smallest amount of stimulation that can be detected. • Just Noticeable Difference (JND) – The smallest amount of change in a stimulus that can be detected. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Measuring Sensory Experience Absolute Sensory Thresholds • 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 Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Sensation • • Vision Hearing Other Senses Keeping the Signals Straight Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Vision The Electromagnetic Spectrum Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Vision Structures of the Human Eye Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Vision Structures of the Human Eye • Cornea – Clear outer membrane that bends light to focus it in the eye. • Pupil – The hole in the iris through which light passes. • Lens – The structure that focuses light on the retina. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Vision The Retina • The rear of the eye where rods and cones convert light into neural impulses. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Vision Visual Pathways Optic Nerve • Pathway that carries visual information from the eyeball to the brain. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Vision Hubel & Wiesel’s Experiment • Hubel and Wiesel’s experiment measured the activity of cells in a cat’s visual cortex. • Cells in the visual cortex that respond only to certain types of visual information, for example, a diagonal line moving up and down, are called feature detectors. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Vision Trichromatic Theory • T. Young (1802) & H. von Helmholtz (1852) both proposed that the eye detects three primary colors: red, blue, & green. • All other colors can be derived by combining these three. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Vision The Color Wheel • Spectral colors vary from violet-blue to red – 470 to 700 nanometer wavelength • Opponent colors are directly across from each other on the wheel. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Vision Test of Color Deficiency Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Vision Opponent-Process Theory – Color vision is derived from three pairs of opposing receptors. The opponent colors are blue and yellow, red and green, and black and white. • This theory explains afterimages (a visual sensation that persists after prolonged exposure to and removal of a stimulus) and color deficiency. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Hearing The Human Ear Audition • The sense of hearing Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Hearing Auditory Localization – 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. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Hearing Common Sounds and the Noise They Produce Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Hearing Disabilities • Conduction Hearing Loss – Caused by damage to the eardrum or bones in the middle ear. • Sensorineural Hearing Loss – Caused by damage to the structures of the inner ear. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Other Senses Olfactory System • Structures responsible for the sense of smell Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Other Senses Taste • Taste buds – Nets of taste-receptor cells • This is a photograph of the tongue’s 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. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Other Senses Temperature • Thermal Grill 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. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Other Senses Pain • Gate-control Theory – Theory that the spinal cord contains a neurological “gate” that blocks pain signals from the brain when flooded by competing signals. • Psychological control – Mind over sensation, distraction Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Other Senses Coordination • Kinesthetic System – Structures distributed throughout body that sense position and movement of body parts. • Vestibular System – The inner ear and brain structures that afford a sense of equilibrium. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Keeping the Signals Straight • Synesthesia – Rare condition in which stimulation in one sensory modality triggers sensations in another sensory modality. • Each sensory system is designed to operate separately from the others. • Sensory Adaptation – A decline in sensitivity to a stimulus as a result of constant exposure. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Perception • • • Perceptual Organization Perceptual Constancies Depth and Dimension Perceptual Set The World of Illusions Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Perceptual Organization Reversible Figures – Drawings that one can perceive in different ways by reversing figure and ground. • Gestalt Psychology – School of thought rooted in the idea that the whole is different from the sum of its parts. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Perceptual Organization Gestalt Laws of Grouping • Proximity – Seeing 3 pair of lines in A • Similarity – Seeing columns of orange and red dots in B • Continuity – Seeing lines that connect 1 to 2 and 3 to 4 in C • Closure – Seeing a horse in D Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Perceptual Organization Identifying Objects • Geons (geometric icons) are simple 3 D component shapes. • A limited number are stored in memory. • Geons are combined to identify essential contours of objects. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Perceptual Constancies • Size Constancy – The tendency to view an object as constant in size despite changes in the size of the retinal image. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Depth and Dimension • Depth Perception – The use of visual cues to estimate depth and distance. • Convergence – A binocular cue involving the turning inward of the eyes as an object gets closer. • Binocular Disparity – A binocular cue whereby the closer an object is, the more different the image is in each retina. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Depth and Dimension Monocular Depth Cues – Distance cues that enable the perception of depth with one eye. • • Relative Image Size Texture Gradient Linear Perspective Interposition Atmospheric Perspective Relative Elevation Familiarity Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Depth and Dimension The Visual Cliff • 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 that they can crawl. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Perceptual Set • What is seen in the center figures depends on the order in which one looks at the figures: – If scanned from the left, a man’s face is seen. – If scanned from the right, a woman’s figure is seen. • This demonstrates the effects of one’s perceptual set. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Perceptual Set Context Effects • 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? Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

The World of Illusions The Müller-Lyer Illusion – Illusion in which the perceived length of a line is altered by the position of other lines that enclose it Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

Extrasensory Perception • The Case for ESP • The Case against ESP • The Continuing Controversy Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

The Case for ESP • Extrasensory Perception (ESP) – The ability to perceive something without ordinary sensory information. – This has not been scientifically demonstrated. • Parapsychologists distinguish between three types of ESP: – Telepathy – Mind-to-mind communication – Clairvoyance – Perception of remote events – Precognition – Ability to see future events Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

The Case against ESP Cards • 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. . Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing

The Continuing Controversy • The ganzfield procedure • Researchers disagree about the reliability of studies done to replicate the ganzfield test. • Visit www. randi. org/ for information about the James Randi Educational Foundation’s million-dollar paranormal challenge. Kassin, Essentials of Psychology - © 2004 Prentice Hall Publishing