Sensation and Perception

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Sensation and Perception
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Grab a scrap sheet of paper

• Write down your definition of
• sensation
• perception

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Sensation

• The process by which our sensory systems (eyes,
  ears, and other sensory organs) and nervous
  system receive stimuli from the environment
• A persons awareness of the world

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Perception

• The process of integrating, organizing and
  interpreting sensations.

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Bottom-Up Processing

• Information processing that focuses on the raw
  material entering through the eyes, ears, and
  other organs of sensation

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Sensation

• Input comes from the five senses
• Visual (Eyes)
• Hearing (Ears)
• Touch (Skin)
• Smell (Nose)
• Taste (Tongue)

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Receptor Cells

• Each of the five senses is specifically coded to
  only take in one type of stimulus, whether it be
  light waves, sound waves, smell, taste, or touch.

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What Does That Mean?

• Turn to your neighbor and tell them what
  sensation means.
• What is with those blasted receptor cells as
  well explain what they do

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Perception

• The process of integrating, organizing and
  interpreting sensations.

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Sensory Receptors

• Specialized cells unique to each sense organ that
  respond to a particular form of sensory
  stimulation.

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Sensory Receptors Example

• A combination of your senses. When you bite into
  a crisp apple, you hear the crunch, you taste the
  sweetness, you feel the smooth skin, you see the
  red, and you smell the aroma.

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Transduction

• The process by which a form of physical energy is
  converted into a coded neural signal that can be
  processed by the nervous system.

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What Does That Mean?

• Turn to your neighbor and tell them what you
  think perception means
• What is the difference between sensation and
  perception?

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What is a Threshold?
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Threshold

• An edge or a boundary
• Walking into the room on one side you are in
  the room on the other you are outside of the room

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Absolute Threshold

• The smallest possible strength of a stimulus that
  can be detected half the time.

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Absolute or Detection Threshold

• The minimum intensity of energy required to
  produce sensation in a receptor cell
• Taste 1 gram of table salt in 500 liters of
  water

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• Touch The wing of a bee falling on your cheek
  from a height of 1 centimeter
• Hearing The tick of a watch from 6 meters away

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• Vision A candle flame on a clear night, 30
  miles away

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Absolute Threshold Example (1)

• Taste 1 gram of table salt in 500 liters of
  water the minimum needed to taste something

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Absolute Threshold (2)

• Vision A candle flame on a clear night, 30 miles
  away the minimum needed to see it. Doesnt
  mean that you can make out what it is

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Just Noticeable Difference Threshold

• The minimum difference that a person can detect
  between two stimuli 50 of the time.

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Webers Law

• The greater the magnitude of the stimulus, the
  larger the difference must be in order to be
  noticed

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Examples

• When you can detect the difference in volume of
  music
• When you can detect the difference in pressure on
  your arm

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Webers Law Example

• If you are carrying 20 lbs. and add 5 lbs., its
  noticeable. If you are carrying 100 pounds and
  add 5 pounds, it may not be noticeable. You need
  to add 10 lbs. to 100 pounds to make it
  noticeable.

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Sensory Adaptation

• When exposed to a stimuli over a period of time
  there will be a diminished sensitivity to it
• If a stimulus is constant and unchanging,
  eventually a person may fail to respond to it

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Example of Sensory Adaptation

• A hot tub after a certain period of time no
  longer seems as hot

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Selective hearing

• Do you think it exists?

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Selective Attention

• Focusing conscious awareness on a particular
  stimulus (sense) to the exclusion of others

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Selective Attention Examples

• Walking down the hallway all 5 senses are
  firing. What grabs your attention?