1. Sensation, Perception, and vision

2. Stimulation of the Senses
Sensation- is the stimulation of sensory receptors and the transmission on sensory information to the central nervous system. Hearing, seeing, tasting, touching, or smelling something.
Perceptions- the psychological process through which we interpret sensory stimulation. Our brain making sense of it a sensations
Absolute Threshold- the weakest amount of a stimulus that can be sensed. These can be different from person to person

3. Absolute Threshold for the senses
Vision- a candle flame viewed from a distance of about 30 miles on a dark night
Hearing- The ticking of a watch from about 20 ft away in a quiet room
Smell- About one drop of perfume diffused throughout a small house
Taste- About 1 teaspoon of sugar dissolved in 2 gallons of water
Touch- The wing of a fly falling on a cheek from a distance less than half an inch
How did they figure this stuff out?

4. Sensory Adaptation
Is the process by which we become more sensitive to weak stimuli and less sensitive to unchanging stimuli
For example, as time goes by in a dark movie theater, you’ll be able to see the people around you better.
Or people who live in busy parts of a big city may get used to the sounds of traffic, unless they hear a firetruck siren.
However we can’t adapt to everything very quickly. Pain take a long time for us to get used to.

5. Signal Detection Theory
Method of distinguishing sensory stimuli, but also accounts for the setting, your physical state, your mood, and your motivations.
For example, let’s say you’re at a coffee shop and you’re sitting outside, if you’re motivated to keep reading your book then you should be able to focus on reading
We tend to focus on what we think is important
If you went to a talent show and a stranger started playing the piano, your mind may wander. But that stranger’s parents will most likely be very engaged.
There are also cases in which we think we perceive a stimulus but there is none. You’re texting that special someone and you keep feeling your phone vibrate in your pocket, but really there isn’t a text

6. Vision
The Blind Spot- when light hits the point where the optic nerve leaves the eye, the eye registers nothing
Find your Blind spot!!!
On your paper draw two circles about the size of a dime. Draw the two circles four inches apart.
Hold the drawing at arms length. Cover your left eye and stare at the circle on the left with your right eye. Focus only on that one circle.
Slowly move the paper toward your face. The circle on the right should “vanish”
Repeat on the other side.

7. Light to Dark Adaptation
Light to dark adaptation takes about 45 minutes
Such as walking into a movie theater or a dark room

8. Afterimages
Ever looked directly at a light for a few seconds and then you still see it even when you look away?
That’s an afterimage!!
- the visual impression that remains after the original image is removed.
Usually remains for a few seconds, but could last a minute after the image has been taken away

9. Dark to Light Adaptation
Dark to light adaptation can take place within about one to two minutes
When you first turn on your lamp in the middle of the night it might hurt your eyes for a second, but soon you’ll blink a few times and you’ll be fine

14. Color Blindness People who do not have normal color vision
People who are completely color blind see the world in black and white, though this is very rare.
Partial color blindness is fairly common. This means they see some colors but not others.
About 99% of people who are color blind have difficulty seeing red and green.
Color blindness is inherited. Males are more likely to be color blind. About 8% of men are as opposed to less than 1% of females.
There is no cure for it, but you can lead a normal life if you are color blind

15. What do you see?

16. If you see an 8, you are not color blind
If you see a 3, you are red-green color blind
If you see no number, you have total color blindness

17. Questions What is an absolute threshold?
What happens when you walk from a room that has light and into a completely dark room? How long might it take your eyes to fully adjust?
How do you think you would respond to a fly buzzing in a room while you were taking an important test? What theory does this relate to?
What might life be like if our senses were not able to adapt?
What is an afterimage?
Imagine that you became completely color blind. How might your life be different from the way it is now? How do you think you would adjust?