Using Art to Introduce Sensation and Perception

1. Using Art to Introduce Sensation and Perception Las Meninas Las Meninas (Spanish for The Maids of Honour) is a 1656 painting by Diego Velázquez, the leading artist of the Spanish Golden Age, in the Museo del Prado in Madrid. The work's complex and enigmatic composition raises questions about reality and illusion, and creates an uncertain relationship between the viewer and the figures depicted. Because of these complexities, Las Meninas has been one of the most widely analyzed works in Western painting.

3. Sensation and Perception 6-8% of the AP Exam

4. Sensation • Definition • Sensation is coordination between: • Receptors • Neural Pathways • Sensory systems are separate but interact with perception.

5. Can you name the senses? • There are 10 (ten) of them!

6. Perception • The process of selecting information from the environment • The interpretation of information from the environment • It is how we make sense of the world

7. Thresholds • Detection Thresholds- minimal amount of stimulus necessary for detection • _______________________ • Detection Threshold

8. Detection Thresholds • Absolute Thresholds-the point at which a stimulus can be detected 50% of the time • Difference Thresholds (jnd) • ______________________ • Absolute Threshold • _______________________ • Detection Threshold

9. Detection Thresholds • Absolute Thresholds • Difference Threshold (JND)- the minimal change in stimulation that can be reliably detected 50% of the time • JND or Difference Threshold • ______________________ • Absolute Threshold • _______________________ • Detection Threshold

10. Gustav Fechner Gustav Fechner • Odd fellow (see notes) • Studied brightness, light and afterimages by looking directly at the sun (Bad Idea!) • Noted for defining absolute threshold and difference threshold • Inadvertent founder of psychophysics • Influenced by Ernst Weber

11. Weber’s law Ernst Weber- 1795-1878 First quantitative law of psychology There is a constant proportion (not constant amount) between the threshold and the stimulus that can be detected. In order for a change in stimulus to be detected, the amount of change needed depends on the present level of stimulation

12. signal detection theory • Proposes that the detection of stimuli involves a decision process as well as a sensory process, which are both influenced by a variety of factors besides stimulus intensity. • Examples • Radar • Pizza Guy

13. Subliminal Perceptions There exists controversy as to whether people actually attend to the information presented below absolute threshold. Will it impact behavior? Backmasking-Jeff Milner sample

14. Receptors • Environmental information exists in many forms • Air vibrations, gases, chemicals, tactile pressures • Receptors cells act as transducers • Receptor activity is subject to change • Sensory adaptation – decline at the receptor level when stimuli are unchanging (EX. Ceiling fan) • Habituation – decline in sensory sensitivity at the neural level due to repeated stimulation • It is different from sensory adaptation in that responsiveness can reappear if stimulation levels are increased or decreased • (EX. Colored paper)

15. Vision

16. Vision • Begins with light entering the eye • Photoreceptors

17. Visible spectrum

18. Structures of the eye • Sclera • Cornea • Iris • Pupil • Lens • Retina – • rods and cones

19. A closer look at the retina • Rods-”see” • Cones-color • Fovea-greatest • visual acuity due • to densely packed • cones • Summation- Rods and cones—bipolar cells—ganglion cells—optic nerve (reduces size of optic nerve but some loss of acuity) • Blind spot • Why is there not hole in your vision?

20. Visual Pathway • Optic Chiasm • Visual Cortex • Hubel and Wiesel – Nobel prize 1981 • Begins with light entering the eye Photoreceptors Visible spectrum

21. Characteristics of Light • Wavelength • (hue) • Intensity • (brightness) • Complexity • (purity or saturation) • It all ends with the “color” we see.

22. Color theories Opponent Process Theory- Two color process as in red vs. green Afterimages • Young –Helmholtz trichromatic theory- three different kinds of cones. • Receptor level • demo

23. Color Deficiencies • Previously called color blindness • Dichromacy • Monochromacy

26. Other Fun Stuff with vision • Afterimages • Pulfrich Phenomenon • Flip books

27. Afterimage

28. Moving on to Audition Gustation Olfaction What are these senses?

29. Audition • It all begins with sound. Listen to this! • (Personal alarm 100db) • Sound is mechanical energy typically caused by vibrating objects • Vibrations produce movement of air molecules called sound waves

30. Structures of the ear Pinna Auditory canal Tympanic membrane Ossicles Cochlea Basilar membrane Organ of corti Hair cells

31. Locating sound How do we locate sounds in our environment? Binaural (two ears)

32. Characteristicsof Sound Frequency (pitch) This is measured by cps Amplitude (loudness/volume) Complexity (timbre/quality) Why do nails on a chalkboard irritate?

33. Auditory Theories • Place Theory- differences in pitch result from stimulation of different areas of the basilar membrane • Frequency Theory- differences in pitch are due to rate of neural impulses traveling up the auditory nerve • This would not explain pitches above 1000Hz (upper 1/3 of piano keyboard) as the frequency of neural firing is only 1000 per second. • Volley Theory- surmises that the neurons fire in sequence as a rhythmic volley at higher frequencies. • Which is best explanation for how we “hear”?

34. Noise Pollution Lengthy exposure of 90 db causes permanent damage 110 db for 30 minutes causes permanent damage 120 db for 5 minutes causes permanent damage Hearing test

35. Deafness- May be caused bytumors, skull injury, poison, birth trauma, rubella • Conductive Deafness –lack of conduction from pinna to basilar membrane • Perceptive Deafness – nerve damage

36. The Chemical Senses Taste and smell are referred to as the chemical sense as they respond to the same environmental stimuli.

37. Gustation • Taste cells are chemical sensitive receptors located in taste bud clusters • Taste buds are located on the • bumps on your tongue

38. Four (five) basic qualities of taste Sweet Sour Salty Bitter Umami Other influences may be smell, temperature or “touch”

39. Linda Bartashuk

40. Olfaction • Receptors for smell are located on the olfactory patch which is a thin membrane in the upper nasal cavity • Olfactory cells are stimulated by gases dissolved in the fluid covering the membrane • For stimulus to be “smelled,” it must be dissolved

41. Topics for discussion • Synesthesia David Eagleman • Asnosmia • Pheromones • In Humans???

42. Somesthesis Skin Kinesthesis Vestibular

43. Skin Senses • Body’s largest sense receptor system • Receptors for this system are located throughout the body

44. Basic sensations Current research does not support the belief that specialized receptor cells for each of the four senses exist Cold Warmth (hot) Pressure Pain

45. A Bit More about each of the skin senses

46. Two-Point Threshold

47. Gate Control Theory (Melzak) • Sensation of pain requires not only that pain information from skin receptors be active, but also the neural gate in the spinal cord to allow these signals to pass to the brain (the gate is closed when critical fibers in the spinal cord are activated) • Pressure stimulation tends to close the neural gate (activate the critical fibers) which is why rubbing a hurt area may relieve pain temporarily.

48. Acupuncture • Stimulation-produced analgesia • Presumably, the needles stimulate nerve fibers that lead to a closing of the pain gate.

49. Kinesthesis • Communicates information about movement and location of body parts • Receptors found in joints, muscles and ligaments • JAX foot asleep?

50. Jax and Beakman • See disc