Sensation and Perception

Grab a scrap sheet of paper   Write down your definition of   sensation   perception

Sensation  The process by which our sensory systems (eyes, ears, and other sensory organs) and nervous system receive stimuli from the environment  A person’s awareness of the world

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

Perception  The process of integrating, organizing and interpreting sensations.

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

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.

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.

What is a Threshold?

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

Absolute Threshold  The smallest possible strength of a stimulus that can be detected half the time.

Absolute Threshold Example   Touch: The wing of a bee falling on your cheek from a height of 1 centimeter

Absolute Threshold Example   Hearing: The tick of a watch from 6 meters away

Absolute Threshold Example  Taste: 1 gram of table salt in 500 liters of water – the minimum needed to taste something

Absolute Threshold  Vision:A candle flame on a clear night, 30 miles away – the minimum needed to see it. Doesn’t mean that you can make out what it is

Absolute Threshold Example  Smell: 1 drop of perfume in a 3 room house.

Weber’s Law  The greater the magnitude of the stimulus, the larger the difference must be in order to be noticed

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

Weber’s Law Example  If you are carrying 20 lbs. and add 5 lbs., it’s 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.

Just Noticeable Difference Threshold  The minimum difference that a person can detect between two stimuli 50% of the time.

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

Example of Sensory Adaptation  A hot tub – after a certain period of time no longer seems as hot

Selective Attention  Focusing conscious awareness on a particular stimulus (sense) to the exclusion of others

Selective Attention Example  Walking down the hallway – all 5 senses are firing. What grabs your attention?