Sensation and Sensation and PerceptionPerception

Grab a scrap sheet of paper

Write down your definition of sensationperception

SensationSensation

The process by which our The process by which our sensory systems (eyes, ears, sensory systems (eyes, ears, and other sensory organs) and other sensory organs) and nervous system receive and nervous system receive stimuli from the stimuli from the environmentenvironment

A person’s awareness of the A person’s awareness of the worldworld

SensationSensation Input comes from the five Input comes from the five

senses:senses:Visual (Eyes)Visual (Eyes)Hearing (Ears)Hearing (Ears)Touch (Skin)Touch (Skin)Smell (Nose)Smell (Nose)Taste (Tongue)Taste (Tongue)

PerceptionPerception

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

Sensory ReceptorsSensory Receptors

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

Sensory Receptors: ExampleSensory Receptors: Example

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

TransductionTransductionThe process by The process by

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

What is a What is a Threshold?Threshold?

ThresholdThreshold

An edge or a boundaryAn edge or a boundaryWalking into the room – on one side Walking into the room – on one side

you are in the room on the other you you are in the room on the other you are outside of the roomare outside of the room

Absolute ThresholdAbsolute Threshold

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

Absolute Threshold ExampleAbsolute Threshold Example

Touch: The wing of a bee falling on your cheek from a height of 1 centimeter

Absolute Threshold ExampleAbsolute Threshold Example

Hearing: The tick of a watch from 6 meters away

Absolute Threshold ExampleAbsolute Threshold Example

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

Absolute ThresholdAbsolute Threshold

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

Absolute Threshold ExampleAbsolute Threshold Example

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

Weber’s Law Weber’s Law

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

ExamplesExamples

When you can detect the difference When you can detect the difference in volume of musicin volume of music

When you can detect the difference When you can detect the difference in pressure on your armin pressure on your arm

Weber’s Law ExampleWeber’s Law Example If you are carrying 20 lbs. and add 5 If you are carrying 20 lbs. and add 5

lbs., it’s noticeable. If you are lbs., it’s noticeable. If you are carrying 100 pounds and add 5 carrying 100 pounds and add 5 pounds, it may not be noticeable. pounds, it may not be noticeable. You need to add 10 lbs. to 100 You need to add 10 lbs. to 100

pounds to make it noticeable.pounds to make it noticeable.

Just Noticeable Difference ThresholdJust Noticeable Difference Threshold

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

Sensory AdaptationSensory AdaptationWhen exposed to a stimuli over When exposed to a stimuli over

a period of time there will be a a period of time there will be a diminished sensitivity to itdiminished sensitivity to it

If a stimulus is constant and If a stimulus is constant and unchanging, eventually a person unchanging, eventually a person may fail to respond to itmay fail to respond to it

Example of Sensory Adaptation Example of Sensory Adaptation

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

Let’s see how good Let’s see how good your your senses are!senses are!

TAKE THE AWARENESS TAKE THE AWARENESS TEST ON THE NEXT SLIDE!TEST ON THE NEXT SLIDE!

Selective AttentionSelective AttentionFocusing conscious awareness on a Focusing conscious awareness on a

particular stimulus (sense) to the particular stimulus (sense) to the exclusion of othersexclusion of others

Selective Attention ExampleSelective Attention Example

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