Sensation and Perception Book Review PDF

# Sensation and Perception Book Review ## 2.1-1 How does selective attention direct our perceptions? * We selectively attend to, and process, a very limited portion of incoming information, blocking out much and often shifting the spotlight of our attention from one thing to another. * Focused in...

# Sensation and Perception Book Review ## 2.1-1 How does selective attention direct our perceptions? * We selectively attend to, and process, a very limited portion of incoming information, blocking out much and often shifting the spotlight of our attention from one thing to another. * Focused intently on one task, we often display inattentional blindness to other events, including change blindness to changes around us. ## 2.1-2 How do our expectations, contexts, motivation, and emotions influence our perceptions? * Perceptual set is a mental predisposition that functions as a lens through which we perceive the world. * Our learned concepts (schemas) prime us to organize and interpret ambiguous stimuli in certain ways. * Our expectations, contexts, motivation, and emotion can color our interpretation of events and behaviors. ## 1.6-1 Which three steps are basic to all of our sensory systems? * Our senses (1) receive sensory stimulation (often using specialized receptor cells), (2) transform that stimulation into neural impulses, and (3) deliver the neural information to the brain. Transduction is the process of converting one form of energy into another. ## 1.6-2 How do absolute thresholds and difference thresholds differ? * Our absolute threshold for any stimulus is the minimum stimulation necessary for us to detect it 50 percent of the time. Signal detection theory predicts how and when we will detect a faint stimulus amid background noise. Individual absolute thresholds vary, depending on the strength of the signal as well as on our experience, expectations, motivation, and alertness. * Our difference threshold (also called the just noticeable difference [jnd]) is the minimum stimulus difference we can discern between two stimuli 50 percent of the time. Weber's law states that two stimuli must differ by a constant minimum percentage (not by a constant amount) to be perceived as different. ## 1.6-3 What is the function of sensory adaptation? * Sensory adaptation (our diminished sensitivity to routine odors, sights, sounds, and touches) focuses our attention on informative changes in our environment. ## 1.6-4 What are the characteristics of the energy that we see as visible light? What structures in the eye help focus that energy? * What we see as light is only a thin slice of the broad spectrum of electromagnetic energy. The portion visible to humans extends from the shorter blue-violet wavelengths to the longer red wavelengths. * After entering the eye through the cornea, passing through the pupil and iris, and being focused by the lens, light energy particles (from a thin slice of the broad spectrum of electromagnetic energy) strike the eye's inner surface, the retina. * Wavelength determines hue, the color we perceive; amplitude determines intensity, the brightness we perceive. ## 1.6-5 How do the rods and cones process information, and what is the path information travels from the eye to the brain? * Light entering the eye triggers chemical changes that convert light energy into neural impulses. * Photoreceptors called cones and rods at the back of the retina provide differing sensitivities -- cones to detail and color, rods to faint light and peripheral motion. * After processing by bipolar and ganglion cells, neural impulses travel from the retina through the optic nerve to the thalamus, and on to the visual cortex ## 1.6-6 How do we perceive color in the world around us? * The Young-Helmholtz trichromatic (three-color) theory proposed that the retina contains three types of color receptors. Contemporary research has found three types of cones, each most sensitive to the wavelengths of one of the three primary colors of light (red, green, or blue). * Hering's opponent-process theory proposed three additional sets of opposing retinal processes (red-green, blue-yellow, white-black). Research has confirmed that, en route to the brain, neurons in the retina and the thalamus code the color-related information from the cones into pairs of opponent colors. * These two theories, and the research supporting them, show that color processing occurs in two stages. ## 1.6-7 Where are feature detectors located, and what do they do? * Feature detectors, specialized nerve cells in the visual cortex, respond to specific features of the visual stimulus, such as shape, angle, or movement. * Feature detectors pass information on to other cortical areas, where supercell clusters respond to more complex patterns. ## 1.6-8 How does the brain use parallel processing to construct visual perceptions? * Through parallel processing, the brain handles many aspects of vision (color, movement, form, and depth) simultaneously. Other neural teams integrate the results, comparing them with stored information and enabling perceptions. ## 1.6-9 What are the characteristics of air pressure waves that we hear as sound? * Sound waves are bands of compressed and expanded air. Our ears detect these brief changes in air pressure. * Sound waves vary in amplitude, which we perceive as differing loudness (with sound intensity measured in decibels), and in frequency (measured in hertz), which we experience as differing pitch. ## 1.6-10 How does the ear transform sound energy into neural messages? * The middle ear is the chamber between the eardrum and the cochlea. * The inner ear consists of the cochlea, semicircular canals, and vestibular sacs. * Sound waves traveling through the auditory canal cause tiny vibrations in the eardrum. The bones of the middle ear amplify these vibrations and relay them to the fluid-filled cochlea. Rippling of the basilar membrane, caused by pressure changes in the cochlear fluid, causes movement of the tiny hair cells, triggering neural messages to be sent (via the thalamus) to the auditory cortex in the brain. * Sensorineural hearing loss (or nerve deafness) results from damage to the cochlea's hair cells or the auditory nerve. Conduction hearing loss results from damage to the mechanical system that transmits sound waves to the cochlea. Cochlear implants can restore hearing for some people. ## 1.6-11 How do we detect loudness, discriminate pitch, and locate sounds? * Loudness is not related to the intensity of a hair cell's response, but rather to the number of activated hair cells. * Place theory (place coding) explains how we hear high-pitched sounds, and frequency theory (temporal coding), extended by volley theory, explains how we hear low-pitched sounds. A combination of the two theories explains how we hear pitches in the middle range. * Sound waves strike one ear sooner and more intensely than the other. The brain analyzes the minute differences in the sounds received by the two ears and computes the sound's source. ## 1.6-12 What are the four basic touch sensations, and how do we sense touch? * Our sense of touch consists of four basic sensations -- pressure, warmth, cold, and pain -- that combine to produce other sensations, such as “itchy” or “wet.” ## 1.6-13 What biological, psychological, and social-cultural influences affect our experience of pain? How do placebos and distraction help control pain? * The biopsychosocial perspective views our perception of pain as the sum of biological, psychological, and social-cultural influences. * Pain reflects bottom-up sensations and top-down cognition. * The gate-control theory of pain suggests that a "gate” in the spinal cord either opens to permit pain signals traveling up small nerve fibers to reach the brain, or closes to prevent their passage. * Pain treatments often combine physical and psychological elements. Placebos can diminish the central nervous system's attention and responses to painful experiences. Distraction can activate neural pathways that inhibit pain and increase pain tolerance. ## 1.6-14 In what ways are our senses of taste and smell similar, and how do they differ? * Taste and smell are both chemical senses. * Taste (gustation) is a composite of six basic sensations – sweet, sour, salty, bitter, umami, and oleogustus - and of the aromas that interact with information from the taste receptor cells of the taste buds. * There are no basic sensations for smell (olfaction). From the top of each nasal cavity, some 20 million olfactory receptor cells for smell send messages to the brain's olfactory bulb, and then onward to the temporal lobe's primary smell cortex and to the parts of the limbic system involved in memory and emotion. ## 1.6-15 How do we sense our body's position and movement? * Position and motion sensors in muscles, tendons, and joints called proprioceptors enable kinesthesis, our sense of the position and movement of our body parts. * We monitor our head's (and thus our body's) position and movement, and maintain our balance, with our vestibular sense, which relies on the semicircular canals and vestibular sacs to sense the tilt or rotation of our head. ## 1.6-16 How does sensory interaction influence our perceptions, and what is embodied cognition? * Our senses influence one another. This sensory interaction occurs, for example, when the smell of a favorite food amplifies its taste. * Embodied cognition is the influence of bodily sensations, gestures, and other states on cognitive preferences and judgments. ## 2.1-3 How did the Gestalt psychologists understand perceptual organization, and how do figure-ground and grouping principles contribute to our perceptions? * Gestalt psychologists searched for rules by which the brain organizes fragments of sensory data into gestalts, or meaningful forms. In pointing out that the whole may exceed the sum of its parts, they noted that we filter sensory information and construct our perceptions. * To recognize an object, we must first perceive it (see it as a figure) as distinct from its surroundings (the ground). We bring order and form to stimuli by organizing them into meaningful groups, following such rules as proximity, similarity, and closure. ## 2.1-4 How do we use binocular and monocular cues to see in three dimensions, and how do we perceive motion? * Depth perception is our ability to see objects in three dimensions and judge distance. The visual cliff and other research demonstrate that many species perceive the world in three dimensions at, or very soon after, birth. * Binocular cues, such as convergence and retinal disparity, are depth cues that rely on information from both eyes. * Monocular cues (such as relative clarity, relative size, texture gradient, linear perspective, and interposition) let us judge depth using information transmitted by only one eye. * The brain computes motion imperfectly, based partly on its assumption that shrinking objects are retreating and enlarging objects are approaching. * A quick succession of images on the retina can create an illusion of movement, as in stroboscopic movement or the phi phenomenon. We may also perceive illusory movement in a still spot of light in a dark room -- the autokinetic effect. ## 2.1-5 How do perceptual constancies help us construct meaningful perceptions? * Perceptual constancies, such as in color, brightness (or lightness), shape, or size, enable us to perceive objects as stable despite the changing image they cast on our retinas. * Our brain constructs our experience of an object's color or brightness through comparisons with other surrounding objects. * Knowing an object's size gives us clues to its distance; knowing its distance gives clues about its size, but we sometimes misread monocular distance cues and reach the wrong conclusions, as in the Moon illusion. ## 2.1-6 What does research on restored vision, sensory restriction, and perceptual adaptation reveal about the effects of experience on perception? * Experience guides our perceptual interpretations. People who are blind from birth and then gain sight after surgery lack the experience to visually recognize shapes and forms. * Sensory restriction research indicates that there is a critical period for some aspects of sensory and perceptual development. Without early stimulation, the brain's neural organization does not develop normally. * People given glasses that shift the world slightly to the left or right, or even upside down, experience perceptual adaptation. They are initially disoriented, but they manage to adapt to their new context.