Sensation and Perception

1. Sensation and Perception Sensation: your window to the world Stimulus from the environment Perception: interpreting what comes in your window. Select, organize, interpret in the bran

2. Bottom-up Processing • Bottom up – a progression from individual elements to the whole • start small then work your way up • Ex. start focusing on trees, then you pay attention to the forest.

3. Top-Down Processing Information processing guided by higher-level mental processes as we construct perceptions, drawing on our experience and expectations. THE CHT

6. Detection Absolute Threshold Intensity No No No Yes Yes Observer’s Response Detected Tell when you (the observer) detect the light.

7. Proportion of “Yes” Responses 0.00 0.50 1.00 0 5 10 15 20 25 Stimulus Intensity (lumens) Thresholds Absolute Threshold:Minimum stimulation needed to detect a particular stimulus 50% of the time.

8. Difference Threshold • The minimum difference that a person can detect between two stimuli. • Also known as Just Noticeable Difference Difference Threshold No Yes No Observer’s Response Tell when you (observer) detect a difference in the light.

9. Weber’s Law Two stimuli must differ by a constant minimum percentage (rather than a constant amount), to be perceived as different. • Would you drive 10 minutes away to save $20 on a meal? • Would you drive across town to save $100 on a $30,000 car?

10. Sensory Adaptation • Decreased responsiveness to stimuli due to constant stimulation. Do you feel your underwear all day?

11. An example of selective attention is: Cocktail Party Effect:ability to listen to one voice among many.

12. Vision • Our most dominating sense. • Visual Capture • http://videos.howstuffworks.com/hsw/11962-light-how-our-eyes-work-video.htm

13. Wavelength • The distance from the peak of one light wave to the peak of the next. The distance determines the hue (color) of the light we perceive.

14. Wavelength (Hue) Violet Green Orange Red Indigo Blue Yellow 400 nm 700 nm Long wavelengths Short wavelengths • Different wavelengths of light result in different colors. • The longer the wave the more red. • The shorter the wavelength the more violet.

15. Intensity The amount of energy (brightness) in a light wave. Determined by the height or amplitude of the wave. The higher the wave the more intense the light is.

16. Intensity (Brightness) Blue color with varying levels of intensity. As intensity increases or decreases, blue color looks more “washed out” or “darkened.”

17. Getting the light in the eye Rods = b/w (light) Cones = color

18. Parts of the eye • Cornea: Transparent tissue where light enters the eye. • Pupil: adjust opening for light • Iris: Muscle that expands and contracts to change the size of the opening (pupil) for light. • Lens: Focuses the light rays on the retina. • Retina: Contains sensory receptors that process visual information and sends it to the brain.

19. Figure 4-3How Light Travels through the Eye Slide 19

20. Transduction • Transforming signals into neural impulses. • Information goes from the senses to the thalamus , then to the various areas in the brain. Remember Ethan in Sky High. He changes his body to slime. Solid form to liquid form. Change from one form of energy to another. Click the picture to watch power placement.

21. Transduction Bipolar cells receive messages from photoreceptors and transmit them to ganglion cells, which all form the optic nerve.

22. The Lens Nearsightedness:A condition in which nearby objects are seen more clearly than distant objects. Farsightedness:A condition in which faraway objects are seen more clearly than near objects.

23. Color Vision Two Major Theories

24. Trichromatic Theory- Young, Hermhotz Any color can be created by combining the light waves of: • Red • Blue • Green • These three types of cones can make millions of combinations of colors. • Most colorblind people simply lack cone receptor cells for one or more of these primary colors

25. If you can’t see the number then you are missing one of your cones.

26. Opponent-Process theory The sensory receptors come in pairs. • Red/Green • Yellow/Blue • Black/White • If one color is stimulated, the other is inhibited.

27. Afterimages

30. Hearing Our auditory sense

31. The Stimulus Input: Sound Waves Sound waves are composed of compression and rarefaction of air molecules.

32. Frequency (Pitch) The number of complete wavelengths that pass through point at a given time. This determines the pitch of a sound.

33. Amplitude (Loudness) Amount of energy in a wave, determined by the amplitude, relates to the perceived loudness. 70dB 120dB

34. The Ear • http://videos.howstuffworks.com/hsw/11925-sound-how-we-hear-video.htm • http://videos.howstuffworks.com/hsw/16895-the-five-senses-hearing-video.htm

35. Outer Ear: • Pinna-(outside w/ skin and cartilage) • External auditory meatus (ear canal) • Collects sounds. Middle Ear: • Chamber between eardrum (tympanic membrane) and cochlea (inner ear) • containing three tiny bones: hammer, anvil, stirrup • concentrate the vibrations of the eardrum on the cochlea’s oval window.

36. Inner Ear:Innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs. • The cochlea is dedicated to hearing • The vestibular system is dedicated to balance

37. Figure 4-5The Human Ear Slide 37

38. Transduction in the ear • Sound waves hit the eardrum then anvil then hammer then stirrup then oval window. • Everything is just vibrating. • Then the cochlea vibrates. • The cochlea is lined with mucus called basilar membrane. • In basilar membrane there are hair cells. • When hair cells vibrate they turn vibrations into neural impulses which are called organ of Corti. • Sent then to thalamus up auditory nerve. It is all about the vibrations!!!

39. Pitch Theories Place Theory and Frequency Theory

40. Place Theory • Different hairs vibrate in the cochlea when they different pitches. • So some hairs vibrate when they hear high and other vibrate when they hear low pitches.

41. Frequency Theory • All the hairs vibrate but at different speeds. Auditory Nerve Action Potentials Sound Frequency 200 Hz

42. Localization of Sounds Because we have two ears, sounds that reach one ear faster than the other ear cause us to localize the sound.

43. Deafness Conduction Deafness Nerve (sensorineural) Deafness The hair cells in the cochlea get damaged. Loud noises can cause this type of deafness. NO WAY to replace the hairs. Cochlea implant is possible. • Something goes wrong with the sound and the vibration on the way to the cochlea. • You can replace the bones or get a hearing aid to help. http://videos.howstuffworks.com/sciencentral/3179-new-hearing-implant-video.htm

44. Touch • Only pressure has identifiable receptors. All other skin sensations are variations of pressure, warmth, cold and pain. • Receptors located in our skin. • Gate Control Theory of Pain Pressure Vibration Cold, warmth and pain

45. Taste • We have bumps on our tongue called papillae. • Taste buds are located on the papillae (they are actually all over the mouth). Salty Sour Umami Bitter Sweet

46. Smell • Like taste, smell is a chemical sense. • Odorants enter the nasal cavity to stimulate 5 million receptors to sense smell. • Unlike taste, there are many different forms of smell.

47. Figure 4-6The Olfactory System Slide 47

48. Kinesthetic Sense • Tells us where our body parts are. • Receptors located in our muscles and joints. Without the kinesthetic sense you could touch the button to make copies of your buttocks.

49. Vestibular Sense • Tells us where our body is oriented in space. • Our sense of balance. • Located in our semicircular canals in our ears.