Sensory Processes Ch07 PDF

SENSATION AND PERCEPTION (Threshold, Senses, and Sensory Problems) Level of Sensitivity in Each Sensory System Threshold refers to the limit below which a stimulus causes no reaction -divides the line between what energy can be detected or not. Absolute Threshold is the minimal a...

SENSATION AND PERCEPTION (Threshold, Senses, and Sensory Problems) Level of Sensitivity in Each Sensory System Threshold refers to the limit below which a stimulus causes no reaction -divides the line between what energy can be detected or not. Absolute Threshold is the minimal amount of energy that can produce a sensation Absolute Threshold Senses Absolute Threshold Equivalent Vision Candle seen 30 miles away on a clear dark night Hearing Tick of a watch 20 feet away in a quiet room Taste Teaspoon of sugar dissolved in 2 gallons of water Touch A bee’s wing falling on the cheek from a height of 1cm Smell One drop of perfume in a 3-room apartment Difference Threshold tells about the minimum difference in the magnitude of two stimuli present Just Noticeable Difference is the minimal amount by which a source of energy must be increased or decreased so that a difference in intensity will be perceived. Signal Detection Theory requires an individual decision making -Noise Sensory Adaptation *Sensitization- we become increasingly sensitive to stimulation *Desensitization- becoming less sensitive to stimulation The Sensory Systems Sense of Sight Light enters the Translation of From retina to eyes and light to neural the primary reaches the signals visual cortex retina Object Light waves Pupil —> Lens Retina (converts (focus) the light to neural signals) Neurons Brain Visual Problems Nearsightedness/ Myopia- a condition where a person is capable of seeing nearby objects with greater activity than distant objects. Farsighted/ Hyperopia- a condition where a person can see distant object with greater activity than nearby objects. Presbyopia- a condition characterized by brittleness of the lens (permits us to focus on objects at varying distance) which usually begins at about 38-46 years old. Strabismus/ Cross-eyed- visual disorder in which both eyes cannot focus on the same point at the same time. Astigmatism- caused by abnormal curvature of the lens, so that images are distorted. Color Blindness- monochromats and sensitive to light and dark only Partial Color Blindness- sex-linked trait (men); dichromats and can discriminate only 2 colors (red& green or blue &yellow) Color Blindness Test Nothing (hidden digit plate) Red-Green deficiency sees 2 Sense of Hearing Object Stimulus: Tympanic Oval window- Sound membrane Round window waves (vibration) Cochlea Auditory Sensory Brain and (encoder) nerve neurons interpretation Auditory Problems Conduction Deafness- damage to the structures of the middle ear (eardrum or bone that conduct and amplify sound waves from the outer area to the inner ear); they profit from hearing aids Sensory neural deafness- loss of hair cells which will not regenerate. People who suffer from this condition are sensitive to sounds of some pitches than others. Stimulation deafness- stems from exposure to very loud sounds. Hair cells might have been damaged. Sense of Smell Object Stimulus: Olfactory Olfactory bulbs Gaseous mucosa (they synapse with particles (receptor cells) the neuron) Sensory Amygdala Thalamus Interpretation neurons (medial nucleus (receives sensory involved in the signals and sends sense of smell) them to the associated primary cortical area) Anosmia/ Smell Blindness- a condition developed for a particular odor which suggest that one kind of receptor has been damaged or degenerated. Nose is sensitive to various basic odors: flowery, misty (soft), musky (strong-smelling reddish-brown substance) , ethereal (delicate and light), pungent (strong smell--frying onions), putrid decaying or rotting), and burnt. Sense of Taste Object Stimulus: Taste Primary taste: Liquid receptors- Sweet, sour, substances taste buds in the bitter, salty, papillae and umami (taste is produced by a different combination of Solitary activity in these nucleus of the five kinds of Neuron carries medulla (they receptors) signals away from synapse on taste buds, while neurons that receiving input from project to the Brain Interpretation many receptors ventral posterior nucleus of the thalamus Ageusia- temporary loss of taste by eating hot food and scraping the tongue. Number of taste cells declines with age; taste loss can be closely associated by the elderly who already suffers from decline of sense of smell. Sense of Touch Object Stimulus: Touch Skin receptors: Pressure evokes Free nerve a burst of firing endings, pacinian in all receptors, corpuscles, which merkel’s disks, corresponds to ruffni endings the sensation of being touched Neural fibers Brain Interpretation (dermatomes) that carry (somatosensor information from cutaneous y cortex in the receptors and other forebrain) somatosensory receptors gather together in nerves and enter the spinal cord via dorsal roots Pain- pain message to the brain is initiated by the release of various chemicals including Prostaglandins which not only facilitate transmission to the brain but also heighten circulation to the injured area causing redness and swelling called Inflammation. -Analgesics (aspirin or ibuprofen) work by preventing prostaglandin production. Acne-occurrence of inflamed or infected sebaceous glands in the skin; a condition characterized by red pimples on the face, prevalent chiefly among teenagers. Psoriasis-skin disease marked by red, itchy, scaly patches Eczema- patches of skin become rough and inflamed Dermatitis- skin becomes red and swollen  Today, I learned/ realized _____ -end of presentation-