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DO NOW:

DO NOW:. Which sense would you be most willing to give up? Which one would you least like to lose?. Unit 4: Sensation & Perception. AP Psychology Ms. Desgrosellier 11.29.2010. Key Ideas. thresholds vision hearing (audition) touch ( somatosensation )

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DO NOW:

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  1. DO NOW: • Which sense would you be most willing to give up? • Which one would you least like to lose?

  2. Unit 4: Sensation & Perception AP Psychology Ms. Desgrosellier 11.29.2010

  3. Key Ideas • thresholds • vision • hearing (audition) • touch (somatosensation) • Chemical senses – taste (gustation) and smell (olfaction) • Gestalt organizing principles • depth perception • perceptual constancy • perceptual adaptation and perceptual set • ESP

  4. Sensation & Perception • How many rectangles do you see???

  5. Sensation & Perception ThEcOwgAvecOla.

  6. Sensation & Perception .rat eht saw tacehT

  7. Sensation & Perception • Sensation: the process by which you detect physical energy from your environment and encode it as neural signals. • Perception: the process that organizes sensory input and makes it meaningful. • This is influenced by your memory, motivation, emotion, and even culture.

  8. Sensation & Perception • Psychophysics: the study of the relationship between physical energy and psychological experiences. • Asks questions about our sensitivity to stimuli.

  9. Thresholds • stimulus: a change in environment that can be detected by sensory receptors. • absolute threshold: the weakest level of a stimulus that can be correctly detected at least half the time (50%).

  10. Thresholds • Studied by Galanter about 50 years ago found the following absolute thresholds: • a candle flame seen at 30 miles away on a dark clear night • the tick of a watch under quiet conditions at 20 feet away • 1 teaspoon of sugar in 2 gallons of water • 1 drop of perfume diffused in a three-room apartment

  11. Thresholds • signal detection theory: minimum threshold changes with fatigue, attention, expectations, motivation, emotional distress, and from one person to another.

  12. Thresholds • Subliminal stimulation: receiving messages below one’s absolute threshold for conscious awareness. • They can have a momentary, subtle effect on thinking.

  13. Thresholds • Difference threshold: minimum difference between any two stimuli that a person can detect 50% of the time. • Just noticeable difference (JND): when you experience the difference threshold. • e.g. adding one penny to a container with 10 pennies is more noticeable than if it had 100 pennies in it.

  14. Thresholds • Weber’s Law: two stimuli must differ by a constant minimum percent (rather than a constant amount). • Sensory adaptation: when a stimulus is unchanging, you become less sensitive to the stimulus. • Allows you to focus your attention on information changes in your environment without being distracted by irrelevant data such as odors or background noises.

  15. DO NOW • In YOUR OWN WORDS, briefly describe the difference between sensation and perception. • Then briefly describe absolute and difference thresholds.

  16. Transmission of Sensory Information • Sensory information of stimuli comes from millions of sensory receptors in your eyes, ears, nose, tongue, skin, muscles, joints, and tendons. • Different receptors detect different types of physical energy.

  17. Transmission of Sensory Information • Transduction: transformation of stimulus energy to the electrochemical energy of neural impulses. • All this sensory information passes through the thalamus, EXCEPT impulses for olfaction/smell.

  18. Transmission of Sensory Information • vision = occipital lobes • hearing = temporal lobes • smell = lower part of the frontal lobes • taste = the junction of the temporal and parietal lobes • body senses = parietal lobes

  19. VISION • Processed in the primary visual cortex in the occipital lobes. • The image formed on your retina is upside down and incomplete. • Your brain fills in information and straightens out the upside down image almost immediately.

  20. Visual Pathway • cornea: transparent, curved layer in the front of the eye that bends incoming light rays. • normal vision: rays of light form a clear image on the retina of the eye.

  21. Visual Pathway • nearsighted: too much curvature of the cornea and/or lens focuses the image in front of the retina so nearby objects are seen more clearly than distant objects.

  22. Visual Pathway • farsighted: too little curvature of the cornea and/or lens focuses the image behind the retina, so distant objects are seen more clearly than nearby objects.

  23. Visual Pathway • Astigmatism: caused by an irregularity in the shape of the cornea and/or the lens. This distorts and blurs the image at the retina.

  24. Visual Pathway • iris: colored muscle surrounding the pupil that regulates the size of the pupil opening. • pupil: small, adjustable opening in the iris that is smaller in bright light and larger in darkness.

  25. THE EYE

  26. Visual Pathway • lens: structure behind the pupil that changes shape, becoming more spherical or flatter to focus incoming rays into an image on the light-sensitive retina. • accommodation: process of changing the curvature of the lens to focus incoming rays into an image on the light-sensitive retina.

  27. THE EYE

  28. Visual Pathway • dark adaptation: gradual increase in sensitivity to low levels of light when it becomes dark.

  29. Visual Pathway • retina: light-sensitive surface in the back of the eye containing rods and cones that transduce light energy. Also has layers of bipolar cells and ganglion cells that transmit visual information to the brain.

  30. DO NOW • BRIEFLY define the following parts of the eye: • cornea • iris • pupil • lens

  31. THE EYE

  32. Visual Pathway • photoreceptors: modified neurons (rods and cones) that convert light energy to electrochemical neural impulses.

  33. Visual Pathway • rods: photoreceptors that detect black, white, and gray, and detect movement. • Necessary for peripheral and dim-light vision. • Distributed throughout the retina, except on the fovea. • lower threshold than cones and are sensitive to light and dark, as well as movement.

  34. Visual Pathway • cones: photoreceptors that detect color and fine detail in daylight or in bright-light conditions. • Most concentrated at the fovea of the retina, none are in the periphery. • Three kinds that are each most sensitive to a different range of wavelengths of light, which provides the basis for color vision.

  35. Visual Pathway

  36. Visual Pathway • fovea: small area of the retina in the most direct line of sight where cones are most concentrated for highest visual acuity in bright light. • optic nerve: nerve formed by ganglion cell axons; carries neural impulses from the eye to the thalamus of the brain.

  37. THE EYE

  38. Visual Pathway • blind spot: region of the retina where the optic nerve leaves the eye so there are no receptor cells; creates an area with no vision.

  39. Visual Pathway • On your post-it note, draw the following image.

  40. Visual Pathway • Close your LEFT eye and look at the plus sign. • Move the card slowly back and forth until the dot disappears. • You have found your blind spot!

  41. DO NOW • BRIEFLY define the following parts of the eye: • retina • rods • cones • optic nerve

  42. Visual Pathway • bipolar cells: second layer of neurons in the retina that transmit impulses from rods and cones to ganglion cells. • ganglion cells: third layer of neurons in the retina, whose axons converge to form the optic nerve.

  43. Visual Pathway

  44. Visual Pathway • acuity: ability to detect fine details, sharpness of vision. Can be affected by small distortions in the shape of the eye. • What are some things that we have talked about that effect acuity?

  45. Visual Pathway • feature detectors: individual neurons in the primary visual cortex/occipital lobes that respond to specific features of a visual stimulus. • e.g. neurons that only respond (fire) to a specific orientation of a line.

  46. Visual Pathway • In a study, kittens were raised in three kinds of environments: • Vertical stripes • Horizontal stripes • Normal visual environment

  47. Visual Pathway • Kittens raised in an environment with only one line orientation only developed feature detectors for that environment! • This means they could only see ONE orientation!

  48. Visual Pathway • parallel processing: simultaneously analyzing different elements of sensory information, such as color, brightness, shape, etc.

  49. Color Vision • The colors of objects you see depend on the wavelengths of light reflected from those objects to your eyes. • Light is the visible portion of the electromagnetic spectrum.

  50. Color Vision

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