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) Hearing (Ears) Touch (Skin) Smell (Nose) Taste (Tongue)

The process of integrating, organizing and interpreting sensations. 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?