Sensation and Perception

1. Sensation and Perception Ciccarelli and White Chapter 3 Introductory Psychology Spring 2014

2. Sensation and Perception • Sense- a system that translates outside information into activity in the nervous system • Sensation- the stimulus message coming from the senses • Transduction- process of converting stimuli • Perception- the process of giving meaning to that message

3. Figure: What Do You See?

4. ABC’s of Sensation • Sensation is the activation of receptors in the various sense organs • Sensory Receptors • Specialized forms of neurons • Not stimulated by other neurons • Stimulated directly by different kinds of energy (light waves, sound waves, etc)

5. Sensory Energy • Wavelength- the distance between peaks in a wave of light and sound • Frequency- number of complete waves, or cycles, that pass a given point per unit of time • Amplitude- the distance between the peak and the baseline of a wave

6. Figure: The Dimensions of a Wave

7. Sensory Systems- How Information gets from Sensation to Perception • Your senses gather information through various forms of energy • This energy is encoded into neuronal activity • Neuronal activity relays signals to the brain

8. Modification of Energy into Neuronal Activity • In some sensory systems the first step in sensation involves modifying the incoming stimulus • Accessory structures complete this modification • The second step in modification is transduction • Transduction is the process of converting incoming energy into neuronal activity • Transduction takes place at structures called receptors

9. Transfer of Information through CNS • Coding translates the physical properties of a stimulus into neural activity • Sensory nerves transfer coded activity to the brain (Thalamus) • Coded information for all senses except smell goes to the Thalamus • Thalamus does some initial processing and sends information to the Cerebral Cortex • Cortex receives input and produces sensation and perception

10. Review of Structures of Forebrain

11. Review: Elements of a Sensory System

12. Sensory Threshold • Sensory Thresholds • Weber’s Law of just noticeable differences • Ex: Sugar in Coffee (20%) • Already have 5 teaspoons, must add 1 teaspoon • Already have 10 teaspoons, must add 2 teaspoons • Coffee regular • Absolute Threshold • Subliminal Perception • Movie • Habituation and Sensory Adaptation

13. The Science of Seeing • The Science of Seeing • Psychological Properties of Light • Three psychological aspects to light • Brightness • Color • Saturation

14. Figure: The Spectrum of Electromagnetic Energy

15. Structures of the Eye • The structure of the eye • Cornea • Aqueous humor • Iris • Pupil • Lens • Vitreous humor • Retina • Cones • Rods • Fovea • Optic Nerve • Blind Spot/ Optic Disc

16. Figure: Major Structures of the Eye

17. Figure: The Lens and the Retinal Image

18. How the Eye Works • Left and Right Visual Fields • Areas of the Retinas • Where the information goes • Optic chiasm • Photoreceptors • Rods • Dark adaptation • Light adaptation • Cones

19. Color vision • Color Vision • Trichromatic Theory • The Afterimage • Opponent-process theory • Lateral geniculate nucleus • Color Blindness

22. Perception of Sound • What is sound • Properties of sound waves • Auditory Spectrum

23. The Structure of the Ear The structure of the ear • The outer ear • The Middle ear • The inner ear • Cochlea • Basilar Membrane-resting place of the organ of Corti • Organ of Corti- contains receptor cells for the sense of hearing • Auditory Nerve- bundle of axons from the hair cells in the inner ear that run to the brain

24. Figure: Structures of the Ear

25. Figure: The Cochlea

26. Perceiving Pitch • Theories of Pitch • Pitch- psychological experience of sound that corresponds to the frequency of the sound waves; higher frequencies are perceived as higher pitches • Place Theory • Frequency Theory • Volley Principle

27. Types of Hearing Impairments • Types of Hearing Impairments • Conduction Hearing Impairment • Hearing aids • Nerve hearing impairment • Tinnitus • Cochlear implants

28. Figure: Sound Waves and Waveforms

29. Table: Intensity of Sound Sources

30. Auditory Pathways to the Brain • Auditory nerve conveys information to the thalamus which then relays it. • Thalamus relays the information to the primary auditory cortex • Cells in the auditory cortex have preferred frequencies. • Auditory cortex also receives information from other senses.

31. Chemical Senses • Chemical Senses • Gustation • Taste buds • Five basic tastes • Supertasters • Olfaction • Definitions • Olfactory receptor cells • Olfactory bulbs

32. Smell, Taste, and Flavor • Smell and taste act as two components of a single system, known as flavor. • Scent and taste pathways converge in the cerebral cortex. • Both tastes and odors prompt strong emotional responses. • Variations in nutritional state affects: • One’s experience of taste and flavor. • One’s motivation to eat particular foods.

33. Figure: The Olfactory System

34. Olfactory System • Unique relationship between smell and memory. • Species variability in sensitivity to odor and dependency on smell for survival. • E.g., humans have about 9 million olfactory neurons while dogs have 225 million. • Many species have an accessory olfactory system that detects pheromones.

35. Somesthetic Senses • Touch, Pressure, Temperature • Types of sensory receptors • Visceral pain, somatic pain • Congenital analgesia • Congenital insensitivity to pain with anhidrosis • Phantom limb • Pain Gate Control Theory

36. Kinesthetic Sense/ Vestibular Sense • Kinesthetic Sense • Vestibular Sense • Otolith organs • Semicircular canals • Motion sickness

37. ABC’s of perception • The ABC’s of Perception • Size, Shape, and Brightness • Gestalt Principles • Figure-ground • Proximity • Similarity • Closure • Continuity • contiguity

38. Figure 3.20: Gestalt Principles of Perceptual Grouping

39. Depth Perceptions Monocular Cues • Linear perspective • Relative size • Overlap • Aerial perspective • Texture gradient • Motion parallax • accommodation

40. Linear perspective

41. Relative Size

42. Overlap

43. Aerial Perspective

44. Texture gradient

45. Depth Perception • Binocular Cues • Convergence • Binocular Disparity

46. Perceptual Illusions • Hermann Grid • Muller-Lyer Illusion • The Moon Illusion • Illusions of motion

47. Hermann Grid

48. Muller- Lyer

49. Other factors that Influence perception • Perceptual sets • Top down processing • Bottom up processing

50. Figure 3.18: Misperceiving Reality Which Line Is Longer? From Gardner "Optical Illusions from Figures that are Undecidable to Hot Dogs That Float, Scientific American, 222, 124, 127 Reprinted with permission