1 / 21

Psychology 100:11 Chapter 5.1 Sensation & Perception

Psychology 100:11 Chapter 5.1 Sensation & Perception. Outline Introduction Syllabus & code of conduct Sensation and Perception Phantom Limb Pain Coding Psychophysics. Study Question:

Download Presentation

Psychology 100:11 Chapter 5.1 Sensation & Perception

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Psychology 100:11 Chapter 5.1 Sensation & Perception

  2. Outline • Introduction • Syllabus & code of conduct • Sensation and Perception • Phantom Limb Pain • Coding • Psychophysics Study Question: • What are four common elements of our various senses? Use examples from two senses to clarify your answer.

  3. Introduction • My Psych 100 web site • Power Point Lectures • Syllabus • Policies • Lab information • Interesting links Psych 100 Page

  4. Ronald Melzack Sensation • Sensation:The experience of a physical stimulus. • The initial steps taken by sense organs and neural pathways to organize information. • Perception:Subsequent organization and meaningful interpretation of physical stimuli. • Later processing steps that lead to internal representations of the stimulus • Ronald Melzack - The “King of Pain?” “Pain is in the brain”

  5. Sensation Vilayanur Ramachandran From: A journey to the center of your mind

  6. Sensation • Three classes of interest • Physical stimuli E.g, visible light, sound waves, odors, etc. • Physiological response Electrical activity in sense organs, nerves, and brain • Sensory experience Psychological sensations E.g., sound, sight, smell, taste, etc.

  7. Sensory Physiology Physiological Response Physical Stimulus Sensory Physiological Psychology Psychophysics Sensory Experience Sensation Domains of questions

  8. Sensation • Sensory coding • Recording music • Vinyl, tape, and digital codes • Physical properties of stimuli -> neural code • nerve impulses

  9. Sensation • Common elements of the various senses • Receptors:Cells that respond to physical stimuli by creating electrical impulses. • Transduction:The process by which stimuli alter the balance of Na+ and K+ until a receptor reaches receptor potential. • Sensory Neurons:Neurons that carry the impulses from the receptor to the CNS. • Sensory Areas:Specific areas of the cerebral cortex designated for analyzing/organizing sensory information.

  10. Sensation • Quantitative and qualitative aspects • During transduction information concerning the quantitative and qualitative aspects of the stimulus are coded. • Quantitative information: The intensity of the stimulus, e.g., sound volume. • Coding quantity: Faster rate of responding • Qualitative information: Type of energy contained in the stimulus, e.g., sound frequency, colour. • Coding quality: Different receptors respond to different forms of energy.

  11. Gustav Fechner Sensation • Psychophysics • Absolute Threshold:The critical level of intensity that gives rise to sensation. • Fechner and the difference threshold • Just Noticeable Difference (JND).The smallest difference between two similar stimuli that can be distinguished. • Weber:The size of a JND depends on stimulus intensity • e.g., 3 people hum + 1 more -> noticeable • 100 people hum + 1 more -> not noticeable

  12. Ernst Weber Sensation • The Weber fraction: • E.g, The Weber fraction for loudness c = 1/10 • If 10 people hum, how many more must be added to notice the difference? Answer: 1 If 50 people hum, how many more must be added to notice the difference? Answer: 5

  13. Sensation • Other Weber Fractions: • Vision: 1/60 • Kinesthesia: 1/50 • Pain: 1/30 • Pressure 1/7 • Smell 1/4 • Taste 1/3

  14. Gustav Fechner Sensation • Fechner’s law:Sensation strength grows as a function of the Log of stimulus intensity • E.g., 15 w, 30 w light bulbs vs. 30 w, 45 w S = k log(I) • Where • S = magnitude of sensory experience • K = a constant • I = stimulus intensity

  15. Sensation • Loudness is measured using this relationship: • S =decibels (dB) • I = sound pressure units • K = 20 Example     Sound pressure units (I)  Log(I)  20Log(I)= dB Softest detectable 1 (100) 0 0 Conversation 1000 (103) 3 60 Bar band 100000 (105) 5 100 Jet airplane 10000000 (107) 7 140 - Loudest Band (130 - 140)?

  16. Sensation • Signal detection theory • Human judgement and the absolute threshold • E.g., A radar operator during 9/11/01 versus a radar operator today • Sensation vs. decision • Discriminating a signal + noise from noise alone • Lax (yea-sayer) and strict (nea-sayer) criterion • E.g., Hits and false alarms on a true-false test

  17. Response Yes No Hit Miss On Stimulus False alarm Correct rejection Off Sensation • Signal detection theory - Payoff matrices

  18. Response True False 90 % 10 % True Test Item 60 % 40 % False Sensation • Signal detection theory - Gullible student (Lax; yea-sayer)

  19. Response True False 60 % 40 % True Test Item 10 % 90 % False Sensation • Signal detection theory - Skeptical student (strict; nea-sayer)

  20. False Alarm Rate .5 1.0 1.0 Lax Hit Rate .5 Strict Sensation • Signal detection theory • Dissociates “Bias” from “Sensitivity • Receiver operator charactistics Bias vs. Sensitivity

More Related