1. CHAPTER 8: SENSATION AND PERCEPTION

2. SECTION 1: SENSATION

3. WHAT IS SENSATION? Def: what occurs when a stimulus activates a receptor Stimulus: an aspect of or change in the environment to which an organism responds

4. SENSATION CONTINUED Perception: organization of sensory info into meaningful experiences Psychophysics: study of the relationships between sensory experiences and the physical stimuli that cause them

5. THRESHOLD Absolute threshold: the weakest amount of a stimulus that a person can detect half the time Humans have a very limited range

6. SENSORY DIFFERENCES Difference threshold: the smallest change in a physical stimulus that can be detected between 2 stimuli Just Noticeable Difference (JND): the smallest increase or decrease in the intensity of a stimulus that person can detect

7. WEBER’S LAW For any change in a stimulus to be detected, a constant proportion of that stimulus must be added or subtracted A.K.A.: Weber-Fechner Law

8. SENSORY ADAPTATION Senses are tuned to change Senses adapt to a constant level of stimulation Necessary to ignore mundane

9. SIGNAL-DETECTION THEORY Def: the study of people’s tendencies to make correct judgments in detecting the presence of stimuli Radar operator

10. PROCESSING STIMULI Preattentive process: extracting information automatically Attentive process: procedure that considers only one part of the stimuli presented at a time Stroop Interference Effect

11. SECTION 2: THE SENSES

12. VISION Most studied sense Pupil: opening in the iris that regulates the amount of light entering the eye Lens: flexible structure that focuses light on the… Retina: innermost coating of the back of the eye, containing light sensitive receptor cells

13. VISION CONTINUED Cones and Rods: light receptors in the retina; convert light energy into neuronal impulses Cones: color Rods: night vision Optic Nerve: the nerve that carries impulses from the retina to the brain

14. COLOR DEFICIENCY Affects 8% of American men; <1% women Dysfunctional cones Red-green Yellow-blue Total deficiency: see in black and white

15. BINOCULAR FUSION Def: the process of combining the images received from the two eyes into a single, fused image Retinal Disparity: the differences between the images stimulating each eye Essential for depth perception

16. NEARSIGHTEDNESS Eyeball is longer than normal Objects focused at a point in front of the retina See objects that are near, but not far

17. FARSIGHTEDNESS Eyeball is too short Objects focused slightly behind the retina Distant objects are clear, near objects are not

18. HEARING Sound waves: vibrations in the air Loudness determined by amplitude (height) of waves Strength determined by decibels >110 decibels damages hearing

19. HEARING Pitch depends on sound wave frequency (rate of vibration of medium through which wave travels)

20. PATH OF SOUND Outer ear (pinna) receives waves Auditory canal vibrates which vibrates the ear drum Middle ear: 3 tiny bones--- hammer, anvil, and stirrup Inner ear: cochlea---liquid moves, tiny hairs detect motion, translate into neuronal input and sent to brain by the Auditory nerve

21. DEAFNESS 2 types: 1) Conduction deafness: hindered physical motion in the outer or middle ear Helped with conventional hearing aid 2) Sensorineural deafness: damage to the cochlea Helped with cochlear implant

22. BALANCE Vestibular system: 3 semicircular canals that provide the sense of balance, located in the inner ear and connected to the brain by a nerve Fluid in canals moves Hair cells translate motion

23. SMELL Chemical sense Gaseous molecules contact smell receptors Olfactory nerve: carries smell impulses from the nose to the brain

24. TASTE 5 primary tastes: 1) Sweet 2) Sour 3) Bitter 4) Salty 5) Umami (savory, meaty) Combination of these creates flavor Taste is more determined by smell

25. SKIN SENSES Densely bundled nerve endings create sensitivity to pressure Some are sensitive to hot and cold Pain results from many different stimuli

26. PERCEPTIONS OF PAIN Sharp, localized pain immediately after injury Dull, generalized pain later Gate control theory of pain: shifting attention away from pain can lessen its effects

27. BODY SENSES Kinesthesis: the sense of movement and body position Cooperates with vestibular system and vision Receptors in and near muscles, tendons, and joints

28. SECTION 3: PERCEPTION The way we interpret sensations and organize them into meaningful experiences

29. GESTALT Def: the experience that comes from organizing bits and pieces of info into meaningful wholes Trying to identify principles the brain uses in building perception

30. GESTALT PRINCIPLES 1) Proximity 2) Continuity 3) Similarity 4) Simplicity 5) Closure If elements are close to one another or similar, we perceive them as one set

31. FIGURE-GROUND PERCEPTION The ability to discriminate btwn a figure and its background Shows we can perceive in more than one way Works with sound as well

32. PERCEPTUAL INFERENCE Filling in the gaps in what our senses tell us Largely automatic and unconscious Depends on experience

33. LEARNING TO PERCEIVE Influenced by needs, beliefs, and expectations If we want something, we’re more likely to see it Perceptual set: twisting truth to fit our own belief system

34. SUBLIMINAL PERCEPTION Subliminal messages: brief auditory or visual messages that presented below the absolute threshold Not really effective

35. DEPTH PERCEPTION

36. MONOCULAR DEPTH CUES Can be used with a single eye Relative height: objects further away are higher on your visual plane Interposition: overlapping Light and shadows: brightly lit objects are closer

37. MORE MONOCULAR CUES Texture-density gradient: close objects have more detail Motion parallax: the apparent movement of stationary objects relative to one another that occurs when the observer changes position

38. MORE MONOCULAR CUES Linear perspective: parallel lines converge in the distance Relative motion: near objects appear to move in the opposite direction that you do; far objects seem to travel with you

39. BINOCULAR DEPTH CUES Depend on movement of both eyes Convergence: eyes turn inward when looking at nearby objects Retinal disparity Large disparity means close; small means far

40. CONSTANCY Def: the tendency to perceive certain objects in the same way regardless of changing angle, distance, or lighting

41. ILLUSIONS Def: perceptions that misrepresent physical stimuli Happens when perceptual cues are distorted so our brains cannot correctly interpret space, size, and depth cues

52. EXTRASENSORY PERCEPTION Def: (ESP) an ability to gain info by some means other than the ordinary senses 4 types: 1) Clairvoyance: perceiving w/o sensory input 2) Telepathy: mind reading 3) Psychokinesis: move things with your mind 4) Precognition: foretell events I’m a big idiot who likes to rob people of their money by preying on their personal loss