1. Sensation and Perception
CHAPTER 4
Sensation and perception form our world. Sensation is processed by physical receptors; perception is a psychological function of interpretation.
Sensation and Perception
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2. Sensory Processes Sensation Perception
Sensation is the process of receiving information from the environment through remarkable receptors in the human body.
Perception
Perception is the psychological process of organizing sensory information to make it meaningful.
These two processes are intermixed.
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3. The body receives information through the five main senses.
Vision
Taste
The Five
Human Senses
Smell
Hearing
Touch
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4. An absolute threshold is the minimal amount of sensory stimulation needed for a sensation to occur.
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5. Vision is the dominant sense.
Click on the arrows for more information.
Retina
Iris
Pupil
Blind Spot
Cornea
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6. The Iris
The iris is a muscle that opens and closes in order to control the amount of light entering the eye.
Iris
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Cornea
Blind spot
Iris
Pupil
Retina
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7. The Cornea The cornea is the outer covering of the eye. Cornea Cornea
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Cornea
Blind spot
Iris
Pupil
Retina
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8. The Pupil The pupil is the opening in the eye. Pupil Cornea Blind spot
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Cornea
Blind spot
Iris
Pupil
Retina
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9. The Retina
The retina is the back of the eye that has receptors for light.
Retina
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Cornea
Blind spot
Iris
Pupil
Retina
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10. The Blind Spot
The blind spot is where the optic nerve exits and there are no receptors for light waves.
Blind Spot
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Cornea
Blind spot
Iris
Pupil
Retina
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11. Blind Spot Demonstration
Close your left eye and stare at the dot and move either forward or backward until the cube disappears.
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12. Rods
Rods are visual receptors that “see” only black and white and are most sensitive in low light.
Cones
Cones are visual receptors that receive color and are most sensitive in daylight.
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13. Rods and Cones 7-8 million 120-125 million How many?
Where concentrated?
Sensitive to light?
Sensitive to color?
million
7-8 million
Periphery of retina
Center of retina
Very sensitive
Low sensitivity
Yes No
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14. Color Vision
Some people cannot tell the difference between certain colors. The most common form is the inability to see the colors of red or green.
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15. The Structure of the Ear
Cochlea
This structure is a snail-shaped part of the ear that has
tiny hairs and fluid that vibrate with incoming sound.
Cochlea
Eardrum
Eardrum
This is a piece of skin stretched over the entrance to the ear and vibrates to sound.
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16. Sound
Audition
Sound is energy; it travels in waves like light, but much slower.
Characteristics
Pitch: how high or low a sound is
Timbre: complexity of tone
Intensity: loudness (measured in decibels)
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17. Cutaneous Senses (Touch)
There are 3 types of receptors:
for pressure
for temperature
for injury or poison
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18. Smell (Olfaction)
The sense of smell performs a critical role in providing information about the food we eat. It is very closely related to the sense of taste.
Animals also use smell (chemicals called pheromones) to communicate sexual interest.
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19. Taste Taste receptors on the tongue are called taste buds.
Salty
Sweet
Sour
Bitter
Taste receptors on the tongue are called taste buds.
There are four types of taste receptors: salty, sweet, sour, and bitter.
These receptors combine sensations to create subtle flavors.
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20. Perception
Perceptual constancies use memory to maintain order in the world.
Size constancy: ability to remember the size of an object no matter where it is located
Color constancy: ability to perceive an object as the same color regardless of the environment
Shape constancy: ability to perceive an object as having the same shape regardless of the angle
Space constancy: ability to judge distance by perceiving either self or object movement
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21. Perceptual Organization
Gestalt: making incomplete organization whole (they way something should be rather than how it actually is)
Similarity: grouping like things together
Proximity: grouping things together that are near each other
Closure: filling in the missing details
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22. Perceptual Organization
Closure
Proximity
Similarity
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23. Perceptual Illusions Which line is longer?
Illusions are misperceptions. They illustrate how we
organize objects into meaningful perceptions .
Franz Müller-Lyer designed this illusion in 1889.
Which line is longer?
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24. The Vertical-Horizontal Illusion
Are the two lines the same length?
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25. Figure-Ground Illusion
In the figure-ground illusion, the figure is in the front while the ground is in the back. Do you see the faces facing one another or do you see the vase?
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26. Which cylinder is largest?
Click the forward arrow to move the cylinder on the right forward to the middle cylinder.
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27. Which cylinder is largest?
Now click the forward arrow to move the cylinder forward to the front cylinder.
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28. Which cylinder is largest?
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29. Summary of Main Topics Covered
Sensory Processes
Vision
Hearing
Touch
Smell
Taste
Perception
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