Chapter 4 Sensation and Perception PDF

Sensation and Perception Chapter 4  Naïve Realism Definition = the belief that our sensory systems are infallible and that our perceptions are perfect representations of the world around us  Sensation 1. Vision 2. Hearing 3. Smell 4. Taste 5. Somatos...

Sensation and Perception Chapter 4  Naïve Realism Definition = the belief that our sensory systems are infallible and that our perceptions are perfect representations of the world around us  Sensation 1. Vision 2. Hearing 3. Smell 4. Taste 5. Somatosensory  Transduction Definition = process of converting an external energy or substance into electrical activity within neurons Occurs via sensory receptors  Sensory receptor Definition = specialized cell responsible for converting external stimuli into neural activity for a specific sensory system https://commons.wikimedia.org/wiki/File:Cone_rode_-es.svg  Sensory Adaptation Definition = process in which activation is greatest when a stimulus is first detected Response to the stimulus declines in strength over time  Vision 1.Cornea 6.Vitreous humor 2.Pupil 7.Fovea 3.Lens 8.Blind spot 4.Ciliary muscles 9.Retina 5.Aqueous humor Cornea Definition = transparent cover for the pupil, lens, and iris Its shape bends incoming light to focus the image at the back of the eye Pupil Definition = circular hole through which light enters the eye Pupillary reflex is a muscle response that dilates or contracts the pupil Lens Definition = part of the eye that changes curvature to keep images in focus Consists of some of the most unusual cells in the body Presbyopia = declining eyesight with age due to the lens becoming more rigid over time Ciliary Muscles Definition = changes the thickness of the lens Ring of smooth muscle fibers Connected to the lens via sensory ligaments Allows the lens to focus on objects depending on their distance  Nearsightedness Definition = inability to see far objects well but able to see close objects clearly Results when images are focused in front of the rear of the eye, due to our cornea being too long Lilienfeld, S.O., Lynn, S.J., Namy, L.L. Woolf, N.J., Cramer, K.M., & Schmaltz, R. (2017). Psychology: From Inquiry to Understanding (3rd Canadian Edition). Toronto: Pearson.  Farsightedness Definition = inability to see close objects well but able to see far objects clearly Results when our cornea is too flat or our eyes are too short Lilienfeld, S.O., Lynn, S.J., Namy, L.L. Woolf, N.J., Cramer, K.M., & Schmaltz, R. (2017). Psychology: From Inquiry to Understanding (3rd Canadian Edition). Toronto: Pearson. Aqueous Humor Definition = transparent, gelatinous fluid supporting the structure of the cornea and lens Vitreous Humor Definition = transparent, gelatinous fluid supporting the primary structure of the eye and retina Fovea Definition = central portion of the retina Responsible for acuity Blind Spot Definition = point of exit of ganglion cell axons where the optic nerve connects to the retina Contains no rods or cones Creates some of the most remarkable visual illusions Retina Definition = membrane at the back of the eye responsible for converting light into neural activity Contains photoreceptors  Photoreceptors Definition = cells that respond to light (or lack there of) Not equally distributed across the retina Two types: a) Rods b) Cones  Rods Definition = receptor cells in the retina that are sensitive to light Long and narrow Located around the peripheral of the retina https://commons.wikimedia.org/wiki/File:Cone_rode_-es.svg  Rods Enable us to see basic shapes and forms Dark adaptation = time in dark before rods regain maximum light sensitivity Contains photopigments called rhodopsin Approx. 125 million/retina  Cones Definition = receptor cells in the retina that are sensitive to detail Cone-shaped Located in the center of the retina https://commons.wikimedia.org/wiki/File:Cone_rode_-es.svg  Cones Enable us to see colour Less sensitive to light Contains photopigments called iodopsin Approx. 6.4 million/retina  Colour Blindness Definition = inability to see some or all colours Most often due to absence or reduced cones due to genetic abnormalities Can also result due to brain injury Males > Females Very rare  Blindness Definition = dramatic reduction or inability to see Vision ≤ 20/200 on Snellen eye chart Can be the result of cataracts, clouding of the lens, or glaucoma To compensate, they often rely on other senses (e.g., touch and hearing)  Visual Agnosia Definition = a condition in which a person can see but cannot recognize or interpret visual information Caused by a disorder in the parietal lobes  Hearing Sound = vibration (waves) Sound waves can travel through gases, liquids, and solids We hear them best, though, when they travel through air  Elements of Sound 1.Frequency 2.Amplitude 3.Timbre  Frequency Definition = number of cycles a sound wave completes in a given time Measured in hertz (Hz) Humans hear sounds between 3—20,000 Hz Lilienfeld, S.O., Lynn, S.J., Namy, L.L. Woolf, N.J., Cramer, K.M., & Schmaltz, R. (2017). Psychology: From Inquiry to Understanding (3rd Canadian Edition). Toronto: Pearson.  Amplitude Definition = strength (or height) of a sound wave Measured in decibels (dB) Lilienfeld, S.O., Lynn, S.J., Namy, L.L. Woolf, N.J., Cramer, K.M., & Schmaltz, R. (2017). Psychology: From Inquiry to Understanding (3rd Canadian Edition). Toronto: Pearson.  Timbre Definition = complexity or quality of sound that makes musical instruments, human voices, or other sounds unique Allows the ear to distinguish sounds with the same pitch and loudness Determined by the harmonic content of a sound and the dynamic characteristics of the sound (e.g., vibrato)  Structure of the Ear 1. Pinna 6. Basilar Membrane 2. Tympanic 7. Cochlear Duct Membrane 8. Organ of Corti 3. Ossicles 9. Hair Cells 4. Oval Window 10.Cilia 5. Cochlea  Outer Ear Components Pinna Definition = structure of the ear that amplifies sound and funnels it down the auditory canal to the tympanic membrane Helps with localization Tympanic Membrane Definition = membrane which vibrates according to the frequency of the sound Commonly known as the “eardrum”  Middle Ear Components Ossicles Definition = structure consisting of three bones that transmit vibrations from the tympanic membrane to the oval window Bones: a) Malleus (Hammer) b) Incus (Anvil) c) Stapes (Stirrup)  Inner Ear Components Oval Window Definition = membrane that receives vibrations from the ossicles and sends it to the cochlea Connects middle and inner ear Cochlea Definition = spiral-shaped and filled with fluid Contains: a) Basilar membrane b) Cochlear duct c) Organ of corti Basilar Membrane Definition = membrane below the organ of Corti that assists in translating vibrations into neural activity via action potentials © 2001 Brooks/Cole – Thomson Learning Cochlear Duct Definition = endolymph filled cavity inside the cochlea Sound vibrations create waves in this fluid triggering movement in the hair cells and cilia © 2001 Brooks/Cole – Thomson Learning Organ of Corti Definition = tissue containing the hair cells (and cilia) necessary for hearing Translates the waves in the endolymph into neural activity via action potentials © 2001 Brooks/Cole – Thomson Learning Hair Cells Attached to the top of each cell in the basilar membrane When the basilar membrane vibrates, it causes movement in the hair cells Each hair cell has many fine filaments called cilia © 2001 Brooks/Cole – Thomson Learning  Cilia Definition = short, microscopic, hair-like structure extending from hair cells Movement of the cilia open ion channels causing the release of neurotransmitters to send signals to the brain  Smell “Olfactory” Humans are only capable of detecting between 2000- 4000 different odours Decreased sense of smell may be an early sign of Alzheimer’s or Parkinson’s disease Women > men  Taste “Gustation” Humans are even less taste-orientated Five basic tastes = sweet, salty, sour, bitter, and umami Taste preferences are primarily culturally determined Emotional disorders (e.g., anxiety and depression) can distort taste perception Contain different papillae (taste buds) with different distributions of receptors  Somatosensory Definition = our sense of touch, temperature, and pain Distinguished via: 1. Skin senses 2. Internal senses 3. Vestibular senses  Skin Senses Nerve endings embedded into the skin send sensory information to the brain Free nerve endings = associated with pain and temperature Specialized nerve endings = associated with touch and pressure  Internal Senses Receptors in the bones, joints, and muscles send sensory information to the brain Tells you where your body parts are with respect to each other  Vestibular Senses Our sense of equilibrium Enables us to sense and maintain our balance as we move about Consists of two vestibular sacs and three semicircular canals in the inner ear  Somatosensory 1.Skin senses 2.Internal senses 3.Vestibular sense  Pain Threshold = point at which we perceived it as painful Gate control theory ̶ The idea that pain is blocked (or gated) from consciousness by neural mechanisms Also, has a large emotional component  Perceptions Definition = the brain’s interpretation of raw sensory inputs When light hits objects, part of it is absorbed while the rest is reflected off the object Our perception of an object’s brightness is influenced by how much light is reflected  Psychophysics of Perception Definition = the study of how we perceive sensory stimuli based on their physical characteristics Ways to measure perception: 1. Absolute threshold 2. Just noticeable difference (JND) 3. Signal detection theory  Absolute Threshold Definition = lowest level of a stimulus needed for the nervous system to detect a change 50% of the time https://www.flickr.com/photos/93413187@N06/8491419973/sizes/l/  Just Noticeable Difference (JND) Definition = smallest change in intensity of a stimulus that we can detect Webster’s Law dictates that there is a constant proportional relationship between JND and the original stimulus intensity  Signal Detection Theory Definition = theory regarding how stimuli are detected under different conditions Two components: a) Signal à The stimulus you are trying to perceive b) Noise à Anything that could distract you from the stimulus  Was the stimulus present? YES NO Did you perceive the FALSE YES HIT ALARM stimulus? CORRECT MISS NO REJECTION  Stages of Perception 1. Sensation ̶ External stimuli trigger action potentials of sensory neurons that travel to the brain 2. Perceptual organization ̶ The process of synthesizing (i.e., grouping) sensory features into internal representations of an external stimulus 3. Identification and recognition ̶ The process of creating perception by identifying and assigning meaning to perceived sensations  Laws of Perceptual Grouping 1. Law of proximity 2. Law of similarity 3. Law of continuity 4. Law of closure 5. Law of symmetry 6. Law of figure-ground  Law of Proximity Definition = objects physically close to each other tend to be perceived as unified wholes Lilienfeld, S.O., Lynn, S.J., Namy, L.L. Woolf, N.J., Cramer, K.M., & Schmaltz, R. (2017). Psychology: From Inquiry to Understanding (3rd Canadian Edition). Toronto: Pearson.  Law of Similarity Definition = we perceive similar objects as composing a whole more than dissimilar objects Lilienfeld, S.O., Lynn, S.J., Namy, L.L. Woolf, N.J., Cramer, K.M., & Schmaltz, R. (2017). Psychology: From Inquiry to Understanding (3rd Canadian Edition). Toronto: Pearson.  Law of Continuity Definition = we perceive objects as wholes, even if other objects block part of them Lilienfeld, S.O., Lynn, S.J., Namy, L.L. Woolf, N.J., Cramer, K.M., & Schmaltz, R. (2017). Psychology: From Inquiry to Understanding (3rd Canadian Edition). Toronto: Pearson.  Law of Closure Definition = when partial visual information is present, our brains fill in what is missing Lilienfeld, S.O., Lynn, S.J., Namy, L.L. Woolf, N.J., Cramer, K.M., & Schmaltz, R. (2017). Psychology: From Inquiry to Understanding (3rd Canadian Edition). Toronto: Pearson.  Law of Symmetry Definition = we perceive objects that are symmetrically arranged as wholes more often than those that are not Lilienfeld, S.O., Lynn, S.J., Namy, L.L. Woolf, N.J., Cramer, K.M., & Schmaltz, R. (2017). Psychology: From Inquiry to Understanding (3rd Canadian Edition). Toronto: Pearson.  Law of Figure-Ground Definition = perceptually, we make an instantaneous decision to focus on what we believe to be the central figure, and largely ignore what we believe to be the background  Perceptual Organization Types of perception processing: a) Bottom-up processing = processing in which a whole is constructed from its parts b) Top-down processing = conceptually driven processing influenced by beliefs and expectations  Perceptual Organization Types of perception processing: a) Bottom-up processing = processing in which a whole is constructed from its parts b) Top-down processing = conceptually driven processing influenced by beliefs and expectations  Perceptual Illusion Parallel processing = ability to attend to many sense modalities simultaneously http://www.nvagt-gestalt.org/afbeeldingen/afb_gestalt_9.jpg