1. Psychology: An Introduction
Benjamin Lahey 11th Edition
Slides by Kimberly Foreman
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2. Sensation and Perception
Chapter Five:
Sensation and Perception
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3. Sensation: Receiving Sensory Messages
What messages can be received?
- stimulus:
any aspect of the world that influences behavior or conscious experience
Virtually anything that can excite receptor
cells can be a stimulus.
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4. Sensation: Receiving Sensory Messages (cont.)
Transduction:
- translating messages
for the brain
- translation of
energy in the
environment
into neural
impulses
- transduced by
sensory
receptor cells
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5. Sensation: Receiving Sensory Messages (cont.)
Sensory limits: how strong must messages be?
- absolute threshold:
- smallest magnitude of a stimulus that can be
detected
- difference threshold:
- smallest difference between two stimuli that can
be detected half the time
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6. Sensation: Receiving Sensory Messages (cont.)
Sensory limits: how strong must messages be (cont.)?
- sensory adaptation:
- when a stimulus is continuously present or repeated
at short intervals, the sensation becomes
gradually weaker
- psychophysics:
- specialty area that studies sensory limits, sensory
adaptation and related topics
- Weber’s law
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7. Vision: Sensing Light Light: - electromagnetic radiation
- includes radio waves and X rays
- only a small portion is visible
waves that vary in frequency and
intensity
- intensity = brightness
- wavelength = hue
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8. Vision: Sensing Light (cont.)
The eye:
- cornea
- iris
- pupil
- lens
- ciliary muscle
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9. Vision: Sensing Light (cont.)
The eye (cont.):
how does it work?
- retina:
- rods
- cones
- fovea
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10. Vision: Sensing Light (cont.)
The eye (cont.):
How does it work?
- optic nerve
- blind spot
- optic chiasm
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11. Vision: Sensing Light (cont.)
Dark and light adaptation:
- dark adaptation:
- in darkness, the rods and cones are not
sensitive enough to be stimulated by the
low-intensity light; they begin to gain
sensitivity by making a fresh supply of the
chemicals used in light reception
- light adaptation:
- when suddenly exposed to intense light, the
visual circuits are overloaded
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12. Vision: Sensing Light (cont.)
Color vision:
- trichromatic theory:
- 3 kinds of cones
that respond to
either red, green
or blue range
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13. Vision: Sensing Light (cont.)
Color vision (cont.):
- opponent process
theory:
two kinds of color-
processing
mechanisms
respond in opposite
ways to the two
pairs of
complementary
colors
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14. Vision: Sensing Light (cont.)
Color blindness:
- genetic defect
- partial color
blindness:
- 8% of males
- 1% of females
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15. Hearing: Sensing Sound Waves
- audition
- sound waves
- frequency of cycles:
- Hertz (Hz)
- intensity:
- decibel (db)
- timbre
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16. Hearing: Sensing Sound Waves (cont.)
The ear:
- outer ear:
- pinna
- external auditory
canal
- middle ear:
- eardrum
hammer, anvil,
stirrup
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17. Hearing: Sensing Sound Waves (cont.)
The ear (cont.):
- inner ear:
- oval window
- cochlea
- round window
- basilar
membrane
- organ of Corti
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18. Body Senses Orientation and movement: - vestibular organ:
semicircular canals:
- saccule
- utricle
- kinesthetic sense:
- kinesthetic receptors:
- cupula
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19. Body Senses (cont.) Skin senses: pressure four types of receptors:
- free nerve endings
- basket cells
- tactile discs
- specialized end
bulbs
- sensitivity:
- Braille
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20. Body Senses (cont.) Skin senses (cont.): - temperature: - hot: - cold:
- intense heat stimulates both warm and cold receptors
- cold:
- generally responsive only to cold temperatures
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21. Body Senses (cont.) Pain: - nociceptors: - pain gates: - brain stem
- spinal cord
- peripheral pain receptors
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22. Body Senses (cont.) Pain (cont.): - brain stem: - gate-control theory
- spinal cord
- peripheral:
- regulation of pain
- phantom limbs
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23. Chemical Senses Taste: - 10,000 taste buds - papillae: - sweetness
- sourness
- saltiness
- bitterness
- fattiness
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24. Chemical Senses (cont.)
Smell:
- olfactory epithelium
- impacts taste
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25. Chemical Senses (cont.)
The pheromone detection:
- important roles in regulation of reproductive
behavior
- released in sweat, saliva or urine
- can influence human reproductive cycles
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26. Perception: Interpreting Sensory Messages
Visual perception:
- perceptual organization
- figure-ground
- continuity
- proximity
- similarity
- closure
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27. Figure-Ground
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28. Continuity
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29. Proximity
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30. Similarity
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31. Closure
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32. Perception: Interpreting Sensory Messages (cont.)
Visual perception (cont.):
- perceptual constancy:
- brightness constancy
- color constancy
- size constancy
- shape constancy
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33. Perception: Interpreting Sensory Messages (cont.)
Visual perception (cont.):
- depth perception:
- monocular cues:
- texture gradient
- linear perspective
- superposition
- shadowing
- speed of movement
- aerial perspective
- accommodation
- vertical position
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34. Texture Gradient
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35. Shadowing
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36. Perception: Interpreting Sensory Messages (cont.)
Visual perception (cont.):
- depth perception (cont.):
- binocular cues:
- convergence:
- eyes must angle inward for a near object
- retinal disparity:
- difference between the images on the two retinas
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37. Perception: Interpreting Sensory Messages (cont.)
Visual perception (cont.):
- visual illusions:
- Ponzo
- Zollner
- Muller-Lyer
- Ames room
- Poggendorf
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38. Perception: Interpreting Sensory Messages (cont.)
Visual perception
(cont.):
- color perception:
- interpreted in the
brain using
contextual clues
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39. Perception: Interpreting Sensory Messages (cont.)
Multisensory perception:
integration and interpretation of
information from multiple senses
at the same time
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40. Perception: Interpreting Sensory Messages (cont.)
Motivation, emotion and perception:
- emotions strongly influence perception - no simple one-to-one relation between
the physical stimulus and what one
perceives
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