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Sensation and Perception

Bringing the outside world into the brain

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Sensation and Perception

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  1. Perception Sensation and

  2. Important Terms • Sensation: a sensory message; transmission of information about the environment to the brain. • Transduction: converting physical energy into neural energy. • Perception: the interpretation of a sensory message by the brain.

  3. The Direction of Sensation Physical Energy  The Receptor  The Receptor Cell  A Neural Signal  The Brain

  4. Sensory Thresholds Can taste 1 teaspoon of sugar in 2 gallons of water. A candle flame can be seen from a distance of 30 miles on a clear night. Can hear the ticking of a wristwatch in a quiet room at 20 feet. Can smell a drop of perfume diffused throughout a 3-room apartment. Can feel a bee's wing fall on your cheek from 1 centemeter.

  5. Subliminal Perception • Stimulation below the threshold of conscious awareness. There is no evidence to support subliminal perception occurring. • Reverse Masking There is no evidence to support reverse masking causes subliminal or any other stimulation.

  6. Subliminal Ads

  7. More Subliminals

  8. Vision • The Structure of the Eye The Cornea The Iris The Pupil The Lens The Retina The Fovea The Optic Nerve

  9. At the rear of the eye is the retina containing the receptor cells. Before light gets to the retina, it passes through blood vessels & connecting cells. The Back of the Eye

  10. Rods are absent from the fovea Rods become more common toward the periphery of the retina Rods have low sensitivity to detail because many of them funnel into a single postsynaptic neuron The Rods

  11. The Cones • More common toward the center of the retina • Fewer in the periphery of the retina • More of them because fewer cones funnel onto a single postsynaptic neuron

  12. The Retina • The Rods Specialized for low light • The Cones Color vision and bright light The rods and cones connect to BI-POLAR cells. The bi-polar cells connect to GANGLION CELLS. The ganglion cells’ axon becomes the OPTIC NERVE.

  13. Trichromatic Theory Three types of cones: RED, GREEN, and BLUE. Opponent Process Theory Cones are in opposing pairs. When one is activated, the other is suppressed. White/Black Blue/Orange Green/Red SeeingColor

  14. The Visible Spectrum • We see about 1/1 millionth of a meter of the whole electromagnetic spectrum. • The electro-magnetic spectrum includes both invisible long and short waves.

  15. Perceiving Reality • Apparent Motion • The Autokinetic Effect Apparent motion of a single light in total darkness. • The Phi Phenomenon A series of blinking lights. • The Stroboscopic Effect The “jerky” effect of a strobe light blinking in total darkness with movement.

  16. Figure – Ground The simplest type of organizational principle Reversible Figure-Ground Unclear Figure-Ground Illusory Figure-Ground Perceptual Organizational Principles

  17. Filling in the Gaps • Closure The tendency to perceive an object or shape even when the form isn’t complete.

  18. Similarity Similar objects are perceived as being together. Proximity Stimuli close together are perceived as being together. Perceiving Depth & Distance

  19. Interposition Something is placed between the eye and the object. Texture Gradient Textured objects further away look smooth. Perceiving Depth & Distance

  20. Linear Perspective Convergence of lines or the vanishing point in art. Aerial Perspective Close objects appear clearer than those farther away. Perceiving Depth & Distance

  21. Motion Paralax Closer objects seem to move faster than those farther away when in motion. Light and Shadow Gives objects the appearance of three dimensions. Perceiving Depth & Distance

  22. Relative Size The smaller the image of an object is on the retina, the farther away it seems. Relative Height Objects higher in the visual field are perceived as farther away. Perceiving Depth & Distance

  23. The Optic Chiasm • Point in the temporal area of the brain where the optic nerve crosses over from left to right. This is where stereo vision is created.

  24. Stereoscopic Vision • Seeing the world in Three-Dimensions • Binocular cues: Retinal Disparity The difference between the two eyes Convergence The eyes focusing close up Stereoscopic Vision Seeing depth naturally

  25. Perceptual Constancies • Size Constancy Objects continue to remain the same size no matter how distant. • Shape Constancy Objects remain the same shape even if the image on the retina shows a different shape. • Color Constancy Influenced by lighting (artificial, colored, or natural).

  26. Visual Illusions

  27. More Illusions

  28. More Illusions

  29. Hearing • The Construction of the Ear The Pinna The External Auditory Canal The Ear Drum The Hammer, Anvil, & Stirrup The Oval Window The Cochlea The Hair Cells The Nerve Cells The Auditory Nerve

  30. Inside the Ear • The Middle & Inner Ear The Eardrum The Hammer, Anvil, & Stirrup The Oval Window The Cochlea The Semicircular Canals

  31. Medical Science Is Always Finding Something New

  32. The Cochlea • The Cochlea is the organ of hearing • Contained within the Cochlea are the hair cells The hair cells are connected to neurons and the axons of the neurons create the auditory nerve.

  33. Theories of Hearing • The Place Theory of Hearing Different areas of the basilar membrane respond to different frequencies. High tones register most strongly at the base of the cochlea (near the oval window), lower tones mostly move the hair cells near the outer tip of the cochlea. • The Frequency Theory of Hearing The entire basilar membrane acts like a microphone, vibrating as a whole in response to sound. The nerve receptors send out impulses that are tied directly to the frequency of the sounds: Frequency = Impulses

  34. Deafness • Conduction Deafness When the eardrums or ossicles are damaged or immobilized by disease or injury reducing the transfer of sound to the inner ear. • Nerve Deafness When there is damage to the hair cells or auditory nerve. • Stimulation Deafness Caused by a noisy environment damaging the hair cells in the cochlea.

  35. The Sense of Smell • Olfaction A chemical sense • The Route Nerve Endings toThe Neuronsto The Olfactory Bulbto The Limbic System • The Lock & Key Theory • 5 Odors Identified Floral, Camphoric, Musky, Minty, & Etherish

  36. Taste • Gustation A Chemical Sense • The Route The Tongue to The Papillae to The Taste Buds to The Brain • 5 Tastes Identified Sweet, Sour, Salty, Bitter, & Umami

  37. Grace and Balance • The Kinesthetic Sense Keeps us informed about movement of body parts & their position in relation to each other. Muscle Movement, Posture, & Joints Information comes from stretch receptors, the tendons, & the internal organs.

  38. Balance & Equilibrium • Vestibular Sense The Vestibular Sense keeps us informed about balance & the position of our body in space. Hair cells in the inner ear bend in relation to the position & movement of the head giving information that the brain uses to help us maintain our balance and to sense changes in our movement through space.

  39. The Tactile Senses • Touch Skin receptors that make us aware of how & where we’re being touched. • Pressure Receptors beneath the skin that make us aware of deeper touch. • Temperature Receptors are found just beneath the skin to give the sensation of hot, cold, and warm.

  40. Pain Pain is adaptive & lets us know there’s something wrong. Pain receptors are located not just in the skin, but also in other parts of the body: muscles, joints, ligaments, teeth, & the internal organs. 2 Kinds of Pain Dull (slow) pain Long axons Sharp (fast) pain Short axons The Gate Control Theory of Pain There is a “neurological gate” in the spinal cord controlling the transmission of pain messages to the brain. Dull, throbbing pain is conducted through the gate by thinner & slower nerve fibers that carry signals for touch & temperature. Faster, thicker nerve fibers cause a bottleneck at the gate, blocking the passage of other messages. The Tactile Senses

  41. What Influences Pain? • The Biosocial Theory The interaction of biological, psychological, and cultural factors influence the intensity & duration of pain. • The Placebo Effect Any direct or indirect procedure or object that can cause relief from pain or illness. With pain, it appears to come from the release of endorphins.

  42. What Influences Our Perceptions? • We respond selectively • Genetics & genetic predispositions • Individual characteristics Motivation Values Expectations Cognitive Style Personality Experience & Culture

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