Sensation and Perception

Our Essential Questions!

How do sensations and perceptions differ? How do the senses transform information

into brain messages? What is the nature of attention?

Grab a scrap sheet of paper

Write down your definition of sensationperception

Sensation

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

mentA person’s awareness of

the world

Perception

The process of integrating, organizing and interpreting sensations.

Bottom-Up Processing

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

Top-Down Processing

Top-Down Processing: expectations and experiences influence how

we interpret incoming sensory information

The Major Senses

7 major senses Vision (most studied) Hearing Touch Smell Taste Vestibular Kinesthetic

The Riddle of Separate Sensations

Sense receptors specialized

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

Sensory Receptors – An Example

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.

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.

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

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.

Sensation & Perception Processes

Principles of Sensation

TransductionAbsolute thresholdDifference thresholdSensory adaptation

TransductionThe process by

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

What Does That Mean?

Turn to your neighbor and tell them what you think perception means…

What is the difference between sensation and perception?

What is a Threshold?

Threshold

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

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

Subliminal Messages?

Absolute Threshold

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

Absolute or Detection ThresholdThe minimum intensity of

energy required to produce sensation in a receptor cell

Taste: 1 gram of table salt in 500 liters of water

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

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

Absolute Threshold Example (1)

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

Absolute Threshold (2)

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

Just Noticeable Difference Threshold

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

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.

Sensory AdaptationWhen 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

The Nature of Attention

Where does attention come into play here?

Hypothetical Situation

What would happen if we had no filter between sensation and perception?”

Hallway example

Sensory Overload

Overstimulation of the senses

Selective hearing

Do you think it exists?

Selective AttentionFocusing conscious awareness on a

particular stimulus (sense) to the exclusion of others

Selective Attention Examples

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

Let’s write!

How do sensations and perceptions differ? How do the senses transform information

into brain messages? What is attention? How much control do

we have over our attention?

Time to get creative!

With your partner, create a poster depicting all 5 of the following: Sensation Perception transduction Selective Attention Absolute sensory thresholds Difference threshold