Sensation is the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment. Perception involves interpreting and organizing these sensory inputs into meaningful experiences. Psychophysics studies the quantitative relationships between physical stimuli and perceptual experiences. The key senses are vision, hearing, taste, smell, touch, and the vestibular and kinesthetic senses. Perception involves organizing sensory information and making inferences to interpret our experiences.

1. Chapter 8 Sensation and Perception

2. Section 1 Sensation

3. What is Sensation? Sensation- what occurs when a stimulus activates a receptor. Perception- the organization of sensory information into meaningful experiences Pyschophysics- the study of the relationships between sensory experiences and the physical stimuli that cause them

4. Threshold Absolute threshold- is the weakest amount of a stimulus that a person can detect half the time Difference threshold- the smallest change in a physical stimulus that can be detected half the time

5. Sensory Differences and Ratios Just noticeable difference (JND)- the smallest increase or decrease in the intensity of a stimulus that a person is able to detect half of the time. Weber’s law: the principle that for any change in a stimulus to be detected, a constant proportion of that stimulus must be added or subtracted.

6. Sensory Differences and Ratios Some senses produce huge increases in sensation in response to a small amount of energy

7. Sensory Adaptation Senses are tuned to change when exposed to stimuli People have the ability to adapt to stimulation in the environment Adjusting to a dark movie theatre Allows us to notice differences in sensations and react to the challenges of different or changing stimuli

8. Signal-Detection Theory Is the study of people’s tendencies to make correct judgments in detecting the presence of a stimuli. Detection thresholds- involve recognizing some stimulus against a background of competing stimuli.

9. Two types of processing stimuli or signals Preattentive process- method for extracting information automatically and simultaneously when presented with stimuli. Attentive process- is a procedure that considers only one part of the stimuli presented at a time.

10. Section 2 The Senses

11. The Senses Vision Hearing Taste Smell Touch Skin senses Vestibular Kinesthetic

12. Vision Most studied of all senses Pupil- the opening in the iris that regulates the amount of light entering the eye Lens- a flexible, elastic, transparent structure in the eye that changes its shape to focus light on the retina

13. Vision Retina- the innermost coating of the back of the eye, containing the light-sensitive receptor cells Rods & cones are responsible for changing light energy into neuronal impulses Optic nerve- the nerve that carries impulses from the retina to the brain

14. Light Is a form of electromagnetic radiation Electromagnetic spectrum is made up of: Radio waves Microwaves Infrared radiation Ultraviolet rays X-rays Gamma rays

15. Light Visible light only makes up a small portion of the electromagnetic spectrum Passing sunlight through a spectrum breaks the light into a rainbow of colors, each color having a different wavelength

16. Color Deficiency If a person’s cones don’t function correctly, the person is color-deficient Fewer people have trouble between red and green than yellow and blue 8% of American men and 1% of American women are color blind/color deficient

17. Binocular Fusion Is the process of combining the images received from the two eyes into a single, fused image Retinal disparity- is the differences between the images stimulating each eye Depth perception Large retinal disparity means object is nearby Small retinal disparity means object is distant

18. Nearsightedness and Farsightedness Long eyeball usually means you are nearsighted You can see objects close to you, but objects in the distance are blurry Short eyeball usually means you are farsighted You can see distant objects clear, but up-close objects are blurry

19. Hearing Depends on the vibration of sound waves in the air Auditory nerve- is the nerve that carries impulses from the inner ear to the brain, resulting in the perception of sound Loudness- determined by amplitude Higher the amplitude, the louder the sound Decibels- sound-pressure energy

20. Hearing Pitch- based on sound wave frequency Low frequency- deep bass sounds High frequency- shrill squeaks You can find the source of a sound when both ears work together

21. The Pathway of Sound Outer ear Receives sound waves and directs sounds through the auditory canal Middle ear- air-filled cavity 3 bones (hammer, anvil, and stirrup) are linked to the ear drum on one end and the cochlea

22. The Pathway of Sound Inner ear Cochlea makes up the inner ear Bony tube that contains fluids and neurons Pressure makes the liquid inside move Tiny hairs in the cochlea pick up motion which are attached to sensory cells These cells turn the sound vibrations into neuronal impulses, which are sent to the brain

23. Deafness Conduction deafness- occurs when something hinders motion through the outer or middle ear or when bones of the middle ear become rigid and cannot carry sounds inward Usually helped with a hearing aid

24. Deafness Sensorineural- occurs from damage to the cochlea, hair cells, or auditory neurons Can be helped by a cochlear implant Cochlear implant- is a miniature electronic device surgically implanted

25. Balance Vestibular system- three semicircular canals that provide the sense of balance, located in the inner ear and connected to the brain by a nerve Over-stimulation of the vestibular sense will make you dizzy and possibly motion sick

26. Smell and Taste Known as chemical senses because their receptors are sensitive to chemical molecules Olfactory nerve- the nerve that carries smell impulses from the nose to the brain Liquid chemicals must stimulate receptors in the taste buds for you to taste something

27. The Skin Senses Skin provides the brain with four kinds of information about the environment: Pressure Warmth Cold Pain Pressure varies from place to place on the skin

28. The Skin Senses Pressure sensations can serve as protection Many things that can produce pain: Scratches, punctures, heat, and cold Pain makes it possible for you to prevent damage to your body

29. Perceptions of Pain Two types of pain sensation sharp- localized pain you may feel immediately after an injury Dull- generalized pain you may feel later Gate control theory of pain- we can lessen some pains by shifting our attention away from the pain impulses or by sending other signals to complete with the pain signals

30. The Body Senses Kinesthesis- The sense of movement and body position Comes from receptors in and near the muscles, tendons, and joints Without kinesthetic sensations your movements would be jerky and uncoordinated

31. Section 3 Perception

32. Perception Is when the brain receives information from the senses and organizes and interprets it into meaningful experiences Goes beyond our reflexive behavior Allows us to confront changes in our environment

33. Principles of Perceptual Organization Gestalt- is the experience that comes from organizing bits and pieces of information into meaningful wholes Psychologists have tried to identify principles the brain uses to construct perceptions Proximity, continuity, similarity, simplicity, closure

34. Figure-ground Perception Is the ability to discriminate properly between a figure and its background. Two dimensional objects are heard to tell the figure from the ground These are important in hearing and vision In music: The melody becomes the figure, the rest of the music becomes the background

35. Perceptual Inference Is the phenomena of filling in the gaps in what our senses tell us is known Usually automatic and unconscious Differs by our experiences

36. Learning to Perceive Something people learn to do Active involvement in the environment is important for accurate perception Is influenced by our needs, beliefs, and expectations Perceptual set- prepares you to see what you want to see

37. Subliminal Perception Subliminal messages: brief auditory or visual messages that are presented below the absolute threshold Subliminal perception: the ability to notice stimuli that affect only the unconscious mind The Hidden Persuaders by Vance Packard believed advertisers were using subliminal advertising in 1957.

38. Depth Perception Being able to recognize distances and 3-D Is being developed as an infant Study: Babies would not crawl of the edge of a table, they realized the difference; so they believe depth perception is developing as an infant

39. Monocular Depth Cues Cues that can be used with a single eye Size of an object Relative height Interposition- overlapping of images Light and shadows Texture-density gradient Motion parallax- is the apparent movement of stationary objects relative to one another that occurs when the observer changes postion

40. Monocular Cues Linear perspective- parallel lines converge when stretched into the distance Relative motion Objects nearby seem to be moving in the opposite direction when focusing on a distant object

41. Binocular Depth Cues Depend on the existence or movement of both eyes Retinal disparity- each eye occupies a different position, each eye receives a different image

42. Constancy The tendency to perceive certain objects in the same way regardless of changing angle, distance, or lighting

43. Illusions Perceptions that misrepresent physical stimuli Perceptual cues are distorted so our brains cannot interpret: Space, size, and depth cues

44. Extrasensory Perception Is an ability to gain information by some means other than the ordinary senses Four types of ESP Clairvoyance- is perceiving objects or information without sensory input Telepathy- involves reading someone else’s mind or transferring one’s thoughts Psychokinesis- moving objects through purely mental effort Precognition is the ability to foretell event

45. Extrasensory Perception Intense personal experience that can be scientifically validated J.B. Rhine- parapsychologist that has been studying ESP since the early 1900s

46. Source: Kasschau, Richard, A. Understanding Psychology . McGraw-Hill, Glencoe, New York, New York, 2008.