Sensation and Perception PDF

9/26/24 SENSATION & PERCEPTION SENSATION...

9/26/24 SENSATION & PERCEPTION SENSATION occurs when special receptors in the sense organs Prepared by: Angelica Amorato, RPm are activated, allowing various forms of outside stimuli to become neural signals in the brain 1 2 TRANSDUCTION SENSORY RECEPTORS the process of converting outside stimuli, such as Specialized forms of neurons. light, into neural activity Stimulated by different kinds of energy rather than by neurotransmitters 3 4 1  9/26/24 SENSE ORGANS receptors are stim ulated by different kinds of energy SENSORY THRESHOLDS Eyes Light JND - Just Noticeable Differences (difference threshold) Ears Vibrations smallest difference between two stimuli that is detectable 50 percent of the time Skin Pressure or Temperature Absolute Threshold Taste buds Chemical Substances lowest level of stimulation that a person can consciously detect 50 percent of the time the stimulation is present Nose Chemical Substances 5 6 JND - Just Noticeable Differences JND - Just Noticeable Differences 7 8 2  9/26/24 JND - Just Noticeable Differences Absolute Threshold 9 10 SUBLIMINAL STIMULI SUBLIMINAL Stimuli that are below the level of conscious awareness limin means “threshold”, sublimin means “below the threshold” PERCEPTION These stimuli are just strong enough to activate the sensory the process by which subliminal stimuli act upon receptors but not strong enough for people to be consciously the unconscious mind, influencing behavior aware of them 11 12 3  9/26/24 HABITUATION SENSORY the tendency of the brain to stop attending ADAPTATION to constant, unchanging information the tendency of sensory receptor cells to become less responsive to a stimulus that is unchanging 13 14 MICROSACCADES STRUCTURE OF THE EYE constant movement of the eyes; tiny little vibrations that people do not notice consciously -- prevent sensory adaptation to visual stimuli 15 16 4  9/26/24 STRUCTURE OF THE EYES STRUCTURE OF THE EYES Cornea - clear membrane that covers the surface of the eye. protects Iris - round muscle (the colored part of the eye) in which the pupil is the eye and focuses most of the light coming into the eye located can change the size of the pupil, letting more or less light into the eye helps focus the image Aqueous humor - clear, watery fluid that supplies nourishment Lens - another clear structure behind the iris, suspended by muscles Pupil - hole through which light from the visual image enters the finishes the focusing process begun by the cornea interior of the eye Vitreous humor - jelly-like fluid that also nourishes and gives shape 17 18 RETINA RETINA Photoreceptors - convert light energy into electrochemical energy that is transmitted by neurons to the brain. There are two kinds of the light focuses on the retina where photoreceptors—rods and cones. electromagnetic light energy is transduced (converted) into neural electrochemical impulse 19 20 5  9/26/24 PHOTORECEPTORS HOW THE EYE WORKS Rods are long and thin Dark adaptation - the recovery Cones are short and thick Light adaptation - the recovery photoreceptors responsible for of the eye’s sensitivity to visual photoreceptors and allow for of the eye’s sensitivity to light night vision and are sensitive stimuli in darkness after the perception of color after exposure to darkness to light and dark stimuli exposure to bright lights 21 22 TRICHROMATIC OPPONENT-PROCESS THEORY THEORY theory of color vision that proposes theory of color vision that proposes four primary colors with cones hree types of cones: red, blue, and green arranged in pairs: red and green, blue and yellow 23 24 6  9/26/24 25 26 COLOR BLINDNESS ROD MONOCHRACY much more common in men than in women, and is genetically linked “Monochrome Blindness” also called Acromacy. can be a result of lesions to the ventro- People with this condition have no color vision at all. It is thus the medial occipital and temporal lobes only true form of pure color blindness. cones are nonfunctional. They see only shades of gray, through the rods 27 28 7  9/26/24 PROTANOPIA STRUCTURE OF THE EAR “Red-Green Color Blindness” is an extreme difficulty in distinguishing red from green although they may be able to distinguish dark red from light green. 29 30 STRUCTURE OF THE EAR STRUCTURE OF THE EAR Auditory canal - short tunnel that runs from the pinna to the Cochlea - snail-shaped structure of the inner ear filled with fluid eardrum (tympanic membrane) Organ of Corti - rests in the basilar membrane. contains receptor Eardrum - thin section of skin that tightly covers the opening into cells for sense of hearing the middle part of the ear. –when sound waves hit the eardrum, it vibrates and causes three tiny bones in the middle ear to vibrate: Auditory nerve - bundle of axons from the hair cells in the inner ear. hammer, anvil, stirrup –receives neural message from the organ of Corti 31 32 8  9/26/24 SOUND Wavelength - interpreted as frequency or pitch (high, medium, low) Amplitude - interpreted as volume (how soft or loud a sound is) CONDUCTIVE Purity - interpreted as timbre (a richness in the tone of the sound) HEARING LOSS Hertz (Hz) - cycles or waves per second, a measurement of can be a result of a damaged eardrum, or a damage to the frequency bones of the middle ear. Hearing soft sounds may be difficult, and louder sounds may be muffled. 33 34 CONDUCTIVE NERVE HEARING HEARING LOSS IMPAIRMENT can be a result of a damaged eardrum, or a damage to the can be a result of a damage in the inner ear or a damage in bones of the middle ear. Hearing soft sounds may be the auditory pathways and cortical areas of the brain. difficult, and louder sounds may be muffled. 35 36 9  9/26/24 TASTE 5 BASIC TASTES Taste buds - taste receptor cells in sweet mouth; responsible for sense of taste sour salty Gustation - the sensation of a taste bitter “brothy,” or umami 37 38 SMELL SOMESTHETIC Olfaction (olfactory sense) - sense of smell SENSES the body senses consisting of the skin Olfactory bulbs - areas of the brain located senses, the kinesthetic sense, and the just above the sinus cavity and just below vestibular senses the frontal lobes that receive information from the olfactory receptor cells “soma”: body “esthetic”: feeling At least 1,000 olfactory receptors 39 40 10  9/26/24 LAYERS SKIN SENSES OF THE SKIN the sensations of touch, pressure, temperature, and pain. these are sensory receptors in the skin 41 42 PERCEPTION SENSORY CONFLICT the method by which the sensations THEORY experienced at any given moment are interpreted and organized in some an explanation of motion sickness in which the meaningful fashion information from the eyes conflicts with the information from the vestibular senses. this results in dizziness, nausea, and other physical discomforts 43 44 11  9/26/24 PERCEPTION KNOWLEDGE IS KEY TO PERCEPTION! the method by which the sensations experienced at any given moment are interpreted and organized in some meaningful fashion 45 46 47 48 12  9/26/24 BOTTOM-UP TOP-DOWN THEORY THEORY perception starts with the stimuli whose perception is driven by high-level cognitive appearance you take in through your eye processes, existing knowledge, and the prior expectations that influence perception 49 50 GESTALT APPROACHES 51 52 13  9/26/24 53 54 FIGURE DEPTH GROUND PERCEPTION the ability to perceive the world in three dimensions 55 56 14  9/26/24 THE MU; LLER-LYER ILLUSION THE HERMANN GRID 57 58 THANK YOU! ILLUSIONS OF MOTION: ROTATING SNAKES due in part to eye movements 59 60 15