Sensation & Perception

2. Sensation & Perception

3. “Sensation is how we take in the world around us (see, hear, feel, touch, taste, etc), and perception is how we make sense of that world”

4. What is Sensation? • The stimulus of sensory receptors and the transmission of sensory information to the central nervous system (the spinal cord and brain). • The stimulation of senses is automatic. • Results from sources of energy such as light or sound or from the presence of chemicals, as in smell and taste.

5. What is Perception? • The psychological process through which we interpret sensory stimulation. • Perception reflects learning, expectations, and attitudes. • Ex: Cars down the road, football players down the field.

6. What is Absolute Threshold? • The weakest amount of stimulus that can be sensed.

7. Absolute Thresholds for Humans

8. Difference Threshold • The minimum amount of difference that can be detected between two stimuli • Black pants, headphones

9. Signal Detection Theory • A method of distinguishing sensory stimuli that takes into account not only their strengths but also such elements as the setting. Your physical state, your mood, and your attitudes. • Ex: someone who sells perfumes, parents at a recital

10. Sensory Adaptation • The process by which we become more sensitive to weak stimuli and less sensitive to unchanging stimuli. • Ex: city dwellers become less aware of traffic

11. Vision The most pathetic person in the world is one who has sight, but no vision” - Helen Keller

12. Light • Light is electromagnetic energy, and is described in wavelengths. • Wavelengths vary in length—some are a few inches long, while some are miles long. • Not all light is visible to humans. • Examples of broken down wavelengths: • Sunlight broken down through water vapor—what helps us see a rainbow. • Sunlight broken down through glass called a prism. • Main colors of the spectrum are red, orange, yellow, green, blue, indigo, and violet. ( ROY G. BIV)

14. The Human Eye

15. The Parts of the Human Eye When you take a picture with a camera, light enters through an opening and is focused onto a sensitive surface—the film. Chemicals on the film are changed by the light and create a lasting impression of the image that entered the camera. When you click the shutter button, the camera quickly switches the mirror out of the way, so the image is directed at the exposed film. The mirror is connected to the shutter timer system, so it stays open as long as the shutter is open. This is why the viewfinder is suddenly blacked out when you take a picture.

16. The Pupil • The amount of light that enters the eye is determined by the size of the opening in the colored part of the eye. • That opening is called pupil. • In the human eye, there is no black spot. • You pupil isn’t a black spot, but rather it is a hole • The size of the pupil adjusts automatically to the amount of light entering the eye. • Pupil is also sensitive to our emotions.

18. Iris • A ring of tiny muscles that control the size of the pupil (the color part of the eye)

19. The Lens • Adjusts to distance of objects by changing its thickness • Ex: finger far from nose close to nose demonstration

20. Retina • The sensitive surface in the eye that acts like the film in a camera. • Difference: retina consists of neurons, not film. • The neurons in the retina that are sensitive to light are called photoreceptors.

21. Optic Nerve • Carries the electrical impulses from the retina to the brain, where they are interpreted as visual images

23. Blind spot • Area by the retina that contains no photoreceptors because that’s where the optic nerve leaves the eye. • If we didn’t have a “blind spot” we wouldn’t be able to see anything.

25. Rods and Cones • Photoreceptors in the retina contain rods and cones • Rods: sensitive only to brightness of light. • They allow us to see black and white. • Cones: provide color vision

27. Visual Acuity • The sharpness of vision • Determined by our ability to see visual details (in normal light)

28. Color Vision • The wavelength of light determines the color • Humans with normal color vision see any color in the visible spectrum of light • Dogs and cats see far fewer colors • Insects, birds, fish, and reptiles experience a wide variety of colors.

29. The Color Circle—Complementary colors

30. After Images • An afterimage of a color is its complementary color • You perceive an afterimage when you have viewed a color for a while and then the color is removed. • The same holds true or black and white. • Staring at one create the other.

35. Color blindness • When someone has an absence of or malfunction in the cones of the retina, they have a form of color blindness • Most common color blindness: red—green color blindness

37. Hearing “Blindness separates us from things, but deafness separates us from people.” -Helen Keller

38. The Ear The ear can be divided into three parts leading up to the brain – the outer ear, middle ear and the inner ear.

39. The outer ear • The outer ear consists of the ear canal and eardrum. Sound travels down the ear canal, striking the eardrum and causing it to move or vibrate.

40. The middle ear • The middle ear is a space behind the eardrum that contains three small bones, the anvil, the stirrup, and the hammer, (called ossicles.) • This chain of tiny bones is connected to the eardrum at one end and to an opening to the inner ear at the other end. Vibrations from the eardrum cause the ossicles to vibrate which, in turn, creates movement of the fluid in the inner ear.

41. The Inner Ear • Movement of the fluid in the inner ear, or cochlea, causes changes in tiny structures called hair cells. This movement of the hair cells sends electric signals from the inner ear up the auditory nerve (also known as the hearing nerve) to the brain. • The brain then interprets these electrical signals as sound.

42. 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. Pg 140) • 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.

43. Touch • Receptors located in our skin. • Gate Control Theory of Pain

44. Taste • Receptor cells are located in taste buds • Taste buds are located in papillae on the tongue • Chemicals dissolve in saliva and activate receptors

45. Taste • We have bumps on our tongue called papillae. • Taste buds are located on the papillae (they are actually all over the mouth). • Sweet, salty, sour and bitter.

46. Smell • Detecting common odors • Odorant binding protein is released and attached to incoming molecules • These molecules then activate receptors in the olfactory epithelium • Axons from those receptors project directly to the olfactory bulb

47. Smell • Women have a better sense of smell than men • Anosmia • Complete loss of the ability to smell

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

49. Kinesthetic Sense • Tells us where our body parts are. • Receptors located in our muscles and joints.

50. Vestibular Senses • Vestibular senses provide information about equilibrium and body position • Fluid moves in two vestibular sacs • Vestibular organs are also responsible for motion sickness • Motion sickness may be caused by discrepancies between visual information and vestibular sensation