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Preview p.24

Preview p.24. What do you see? Describe the sensory processing that is occurring as you view this painting. The Forest Has Eyes. Sensation. pp.196-208 NB p.25. Objective 1: What is the difference between bottom-up and top-down processing?.

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Preview p.24

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  1. Preview p.24 • What do you see? Describe the sensory processing that is occurring as you view this painting.

  2. The Forest Has Eyes

  3. Sensation pp.196-208 NB p.25

  4. Objective 1: What is the difference between bottom-up and top-down processing? • Bottom-up processing: analysis that begins with the sensory receptors and works up to the brain’s integration of sensory information • Top-down processing: information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations.

  5. Objective 1: What is the difference between sensation and perception? • Sensation: the detection of physical stimulus in the environment. • Perception: the interpretation of sensation.

  6. Psychophysics • The study of relationships between physical stimuli, and our psychological experience of them. • Gustav Fechner

  7. Objective 2: What is the difference between absolute and difference thresholds? • Absolute threshold: the smallest amount of stimulus energy necessary for sensation to take place 50 percent of the time. • Difference threshold: the just noticeable difference (JND); the smallest detectable “difference” between two stimuli

  8. Subliminal Messages • Brief auditory or visual messages presented below the absolute threshold so there is less than a 50% chance they will be detected • Used in advertisements, motivation • Little effect according to psychological research. • Subliminal Messages are illegal in the United States to use in TV and radio

  9. Can you see the arrow?

  10. Hidden Messages • They are not subliminal! They are above the absolute threshold, but just barely. You have to seek them out.

  11. Hidden Mickey

  12. Why Hidden Messages? • They include sexual messages to get the interest of adults, so that the cartoons are not just of interest to children. • They make the movie more memorable and more popular, even when done in this slight subliminal fashion. • They include them now simply as it is expected, and there is a game to find the messages when a new movie comes out. • They generate extra publicity and any publicity is good publicity and raises the profile of the movie.

  13. Signal detection theory • Study of people’s tendencies to make correct judgments in detecting the presence of stimuli • How well do your senses stack up?

  14. Touch Threshold Experiment • Each pair will receive two toothpicks taped together. • One partner will close his or her eyes and the other partner will LIGHTLY poke the him or her with one or both toothpicks. • The partner being poked will report whether he or she felt one or two points. • Try this on various parts of the body (school appropriate!), like the face, the forearm, the fingertip, the foot, etc. • Record the body part tested and whether the subject guessed correctly by creating a table on a half sheet of paper. • Switch roles and run the experiment again. • Respond to this question at the end of the experiment. What does this experiment tell us about the varying sensitivity of different areas of the body? • Everyone will turn in table showing the results of their partner and response to question.

  15. Difference Thresholds • The minimum difference between two stimuli required for detection 50% of the time • Also known as… just noticeable difference • Weber’s Law: two stimuli must differ by a constant minimum percentage for their difference to be perceptible

  16. Objective 3: What is sensory adaptation? • Sensory receptors lose their sensitivity in response to unchanging stimulus

  17. Objective 3: How do we benefit from being unaware of unchanging stimuli? • Enables us to focus on informative changes in our environment without being distracted by the uninformative constant stimulation of garments, odors, and street noise. • Frees up our attention • **Television

  18. “We need above all to know about changes; no one wants or needs to be reminded 16 hours a day that his shoes are on.” -Neuroscientist David Hubel (1979)

  19. Process p.24 • What types of sensory adaptation have you experienced in the last 24 hours?

  20. Objective 4: What is transduction? • Conversion of one form of energy to another. • Sensory systems encode stimulus energy as neural messages • Eyes transduce (transform) light energy into neural messages  brain  what you consciously see

  21. Objective 4: What sort of energy does our visual system intake? • Light = electromagnetic energy

  22. Objective 5: What are the major structures of the eye? • Pupil: the opening in the eye that allows light to enter • Iris: a muscle that determines the amount of light that enters through the pupil; colored portion that constricts and expands • Lens: located directly behind the pupil, bends the light wave, focusing it on the retina • Retina: light sensitive inner surface located in the back of the eye; where transduction occurs

  23. Objective 5: What are the major structures of the eye?

  24. Objective 5: How do the structures of the eye guide incoming light toward receptor cells? • Light passes through cornea • Light passes through pupil • Lens bends the light wave to focus on retina • Accommodation refers to the process of how the lens focuses in an out on images • Retina contains photoreceptors (rods and cones) • Greatest concentration of cones is on fovea • Bipolar cells are specialized neurons that connects rods and cones to ganglion cells • Ganglion cells optic nerve which carries info to brain • A blindspotoccurs where optic nerve leaves retina

  25. Nearsightedness: nearby objects are seen more clearly than distant objects. • Farsightedness: far away objects are seen more clearly than near objects

  26. Objective 6: How does the retina react to light? • Produces chemical changes that generate neural signals  activate bipolar cells  active ganglion cells • Ganglion cells form the optic nervewhich carries information to your brain

  27. Objective 6: What are the differences between rods and cones? • Rods • Active in dimly lit conditions • Detect black, white, and gray • Peripheral and twilight vision • Cones • Active in brightly-lit conditions • Detect fine details and color • Daylight vision • Cluster around fovea

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