1. Good Morning!
Write these questions down, we will answer them “Art Gallery” style in a moment
What is happening in this picture?
Who is going up? Who is going down?

3. Where we left off on Friday…

4. Sensory Adaptation Sensation is influenced by change
Our body adjusts to external stimuli after a while… it shifts to the background and we become unaware of it.
We ignore it without even thinking.
Examples….

5. Examples of Sensory Adaptation
Traffic in the city.
A hot shower.
Seeing in the dark.
Gym smell
The “E-Building Funk”
The hum of a refrigerator.
Loud music
Etc…

6. Detection of Threshold
Absolute Threshold
The weakest stimulus that an organ can detect.
Because there is a fuzzy line between detection and non-detection, a person’s absolute threshold is not absolute.
Detection of Threshold
Light
A candle flame at 30 miles on a dark, clear night.
Sound
The tick of a mechanical watch under quiet conditions at 20 feet.
Taste
One teaspoon of sugar in two gallons of water.
Smell
One drop of perfume diffused into the entire volume of a three-bedroom apartment.
Touch
The wing of a bee falling on your cheek from a distance of one centimeter.

7. Difference Threshold
The smallest amount by which a stimulus can be changed and the difference be detected, half of the time.
Think about when you are watching TV and a commercial comes on. Can you tell a difference?
Examples: different shades of a color on a car;

8. Signal Detection Theory
Sensations depend on the characteristics of the stimulus, the background stimulation and the detector.
This theory takes the observer’s characteristics into account
Example: the setting, your physical state, mood, attitude, motivation, etc…

10. Signal Detection Theory
This theory recognizes that the observer, whose physical and mental characteristics are always in flux, must compare a sensory experience with ever-changing expectations and biological conditions.
A_ _OM_BI_E

11. SO! Let’s talk about Vision!

12. Vision
Vision is the most complex, best developed and most important sense for humans and other creatures.
The eye is the brain’s camera.
It gathers light, focuses it, converts it to a neural signal and sends these signals on for further processing.

14. Pupil Pupil: controls the flow of light into the eye
Think of it as the lens of your camera

15. Lens Lens: keeps objects in focus by changing its thickness
Think of it like the focus on a camera

16. Retina
Retina: Surface of your eye that changes light waves to neural images
Photoreceptors: Neurons located in the retina.
Think of these as your camera’s film

17. Photoreceptors
Photoreceptors: Light-sensitive cells (neurons) in the retina that convert light energy into neural energy.
Rods: Photoreceptors that are especially sensitive to dim light, but not color.
Cones: Photoreceptors that are especially sensitive to colors but not dim light.
Cones are responsible for our ability to “see” colors.

18. Photoreceptors: Rods, Cones

19. The Optic Nerve and The Blind Spot
Optic Nerve: The bundle of neurons that carries visual information from the retina to the brain.
This is where the stimulus, once changed into a neural impulse, gets passed onto the brain.
Blind Spot: The point where the optic nerve exits the eye and where there are no photoreceptors. Any stimulus that falls on this area cannot be seen.

20. The Fovea The fovea is the area of sharpest vision.
It has the highest concentration of rods and cones.

21. The Visual Cortex
In the visual cortex, the brain begins working by transforming neural impulses into visual sensations of color, form, boundary and movement.
The visual cortex takes the two-dimensional patterns from each eye and assembles them into a three-dimensional world of depth.

22. Continued Processing
With further processing, the cortex combines these sensations with memories, motives, emotions, and sensations to create a visual world.

23. Color Blindness
Not everyone sees color the same way; some people are born with a color deficiency.
Some people can see no color at all, and are totally color blind, it is rare.
More common is color weakness, where people have a hard time distinguishing between certain colors.

24. The Visual Pathway