Sensation and Perception Grab a scrap sheet of

Sensation and Perception

Grab a scrap sheet of paper ØWrite down your definition of Øsensation Øperception

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

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

Perception ØThe process of integrating, organizing and interpreting sensations.

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

Sensory Receptors: Example Ø 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 Ø 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 Ø An edge or a boundary Ø Walking into the room – on one side you are in the room on the other you are outside of the room

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

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

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

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

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

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

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

Weber’s Law Example Ø 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 ØThe minimum difference that a person can detect between two stimuli 50% of the time.

Sensory Adaptation ØWhen exposed to a stimuli over a period of time there will be a diminished sensitivity to it ØIf a stimulus is constant and unchanging, eventually a person may fail to respond to it

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

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

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