Sensation and Perception: Understanding the Senses and How We Perceive the World

1. Chapter 8Sensation & Perception

2. Sensation & Perception • Sensation • What occurs when a stimulus activates a receptor. • Perception • The organization of sensory information into meaningful experiences.

3. Psychophysics • The study of the relationships between sensory experiences and the physical stimuli that caused them.

4. Thresholds Absolute threshold 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 between two stimuli. Also known as the JND

5. Approximate absolute thresholds for the 5 senses: • Vision - Candle flame seen at 30 miles on a clear, dark night. • Hearing - Tick of a watch under quiet conditions at 20 feet. • Taste - 1 Teaspoon of sugar in 2 gallons of water. • Smell - 1 Drop of perfume diffused into a three-room apartment. • Touch - A bee's wing falling on your cheek from 1 centimeter above.

6. Weber’s Law For any change in a stimulus to be detected, a constant proportion of that stimulus must be added or subtracted.

7. Your senses are most responsive to increases and decreases, and to new events rather than to ongoing, unchanging stimulation. Sensory Adaptation

8. The Stroop Effect

9. THE EYE Video

10. How do we interpret sensations? • STIMULUS - energy that affects what we do. • RECEPTORS – specialized cells that convert environmental energies into signals for the nervous system.

11. PUPIL – an adjustable opening that regulates the amount of light entering the eye. IRIS – the colored structure on the surface of the eye. The Structure of the EYE

12. CORNEA – a rigid transparent structure on the outer surface of the eyeball. LENS – a flexible, transparent structure in the eye that changes its shape to focus on the retina. The Structure of the EYE

13. RETINA – a layer of visual receptors covering the back surface of the eyeball. The Structure of the EYE

14. The RETINA contains 2 types of receptors: • Rods • Black & white vision • Work best at night • 125 million • Cones • Color vision • Work best in daylight • 7 million

15. The Structure of the EYE Optic Nerve – the nerve that carries impulses from the retina to the brain.

16. The Structure of the EYE • Blind Spot – The point where the optic nerve exits the eye and where there are no photoreceptors. Also on page 216.

17. Interactive

18. The Detection of Light • ELECTROMAGNETIC SPECTRUM – the continuum of all the frequencies of radiated energy. • Visible light, what human eyes can see, is only a small part of the entire spectrum.

20. Color Deficiency • Color deficiency -inability to distinguish one color from another.

21. Binocular Cues Binocular Fusion The process of combining the images received from the 2 eyes into a single image. Retinal Disparity The differences between the images stimulating each eye.

22. Nearsighted vs. Farsighted Video Clip

24. Process of Hearing • Video Clip

25. Hearing • Auditory Nerve • The nerve that carries impulses from the inner ear to the brain, resulting in the perception of sound.

27. Deafness • Conduction Deafness • Hearing loss that results when the bones connected to the eardrum fail to transmit sound waves properly to the cochlea.

28. Deafness • Nerve Deafness • Hearing loss that results from damage to the cochlea, the hair cells, or the auditory nerve.

30. 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.

31. 3 Semicircular Canals

32. The Vestibular Sense • If you spin hard enough and then suddenly stop, the tiny current keeps going for a little bit, which gives you the sensation that you are still spinning, but in the opposite direction.  • Your brain may try to compensate for this, and cause you to fall or at very least feel dizzy.

33. Olfaction • Sense of smell. • Smell can influence mood, memory, emotions, matechoice, and the endocrinesystem (hormones).

34. Smell • Olfactory nerve • The nerve that carries smell impulses from the nose to the brain.

35. TASTE • The sensory system that responds to chemicals on the tongue. • Taste Buds • The site of the taste receptors, located in the folds on the surface of the tongue.

36. TASTE RECEPTORS • Sweet • Salty • Sour • Bitter • Umami?

37. TASTE & SMELL • Our sense of smell is responsible for about 80% of what we taste. • Without our sense of smell, our sense of taste would be limited. • Our sense of smell becomes stronger when we are hungry.

38. Skin Senses • Skin senses include pressure on the skin, warmth, cold, pain, vibration, movement across the skin, and stretch of the skin. The skin has 3 types of sensation:  1. pressure 2. temperature 3. pain

39. The Gate Control Theory Pain messages must pass through a gate, probably in the spinal cord, that can block these messages.

40. Body Senses Kinesthesis The sense of movement and body position. Receptors in the muscles, tendons, and joints.

41. PERCEPTION

42. Sensation & Perception • Sensation • What occurs when a stimulus activates a receptor. • Perception • The organization of sensory information into meaningful experiences.

43. Figure and Ground • An object and its background.

46. Aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it dseno't mtaetr in waht oerdr the ltteres in a wrod are, the olny iproamtnt tihng is taht the frsit and lsat ltteer be in the rghit pclae. The rset can be a taotl mses and you can sitll raed it whotuit a pboerlm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe.

47. Gestalt Psychology   The whole is greater than the sum of its parts.

48. The Gestalt Laws of Perceptual Grouping Proximity Continuity Similarity Simplicity Closure video clip

49. The Gestalt Approach • Proximity – we tend to group objects together when they are near each other.

50. The Gestalt Approach • Continuity – we prefer perceptions of connected and continuous figures to disconnected and disjointed ones.