1. REVIEW SLIDES Visual Perception & Audition Quiz on Tuesday, 12/9

2. Parallel Processing Turning light into the mental act of seeing:
light waveschemical reactionsneural impulsesfeaturesobjects
and one more step...
Parallel processing: building perceptions out of sensory details processed simultaneously in different areas of the brain. For example, a flying bird is processed as:
Click to reveal bullets and example.

3. Visual Processing
No animation.

4. Color Vision
Young-Helmholtz Trichromatic (Three-Color) Theory According to this theory, there are three types of color receptor cones--red, green, and blue. All the colors we perceive are created by light waves stimulating combinations of these cones.
No animation.

5. Color Blindness
People missing red cones or green cones have trouble differentiating red from green, and thus have trouble reading the numbers to the right.
Opponent-process theory refers to the neural process of perceiving white as the opposite of perceiving black; similarly, yellow vs. blue, and red vs. green are opponent processes.

6. Opponent-Process Theory Test
Instructor: Tell the students: “Stare at the center dot for 30 seconds; if you’re doing it well, the flag will start to disappear. If it does, keep staring at the dot.”
Further narration as they stare at the dot: “If opponent-process theory is correct, then fatiguing our perception of one will make a blank slide look like the opposite color… and the opponent processes are white vs. black, red vs. green, and yellow vs. blue.”
Click to make flag disappear.
What do you see?
The dot, the dot, keep staring at the dot in the center…

7. Turning light waves into mental images/movies
Turning light waves into mental images/movies... Visual Perceptual Organization
We have perceptual processes for enabling us to organize perceived colors and lines into objects:
grouping incomplete parts into gestalt wholes
seeing figures standing out against background
perceiving form and depth
keeping a sense of shape, size, and color constancy despite changes in visual information
using experience to guide visual interpretation
Restored vision and sensory restriction
Perceptual adaptation
Click to reveal bullets.
This is a summary slide for this upcoming section, listing the major concepts and not the section headings.

8. The Role of Perception
Our senses take in the blue information on the right. However, our perceptual processes turn this into:
a white paper with blue circle dots, with a cube floating in front.
a white paper with blue circle holes, through which you can see a cube.
a cube sticking out to the top left, or bottom right.
blue dots (what cube?) with angled lines inside.

9. Figure-Ground Perception
In most visual scenes, we pick out objects and figures, standing out against a background.
Some art muddles this ability by giving us two equal choices about what is figure and what is “ground”:
Click to reveal bullets and two examples.
Goblet or two faces?
Stepping man, or arrows?

10. Grouping: How We Make Gestalts
“Gestalt” refers to a meaningful pattern/configuration, forming a “whole” that is more than the sum of its parts.
Three of the ways we group visual information into “wholes” are proximity, continuity, and closure.
Click to show a different perspective on each image.
Instructor: perhaps you can get students to bring out the definitions of the concepts in these pictures (as you click to reveal the animations).
“Proximity” means we tend to see objects that are close together as being part of the same object.

11. Which ones influence perception here?
Grouping Principles
Which ones influence perception here?
Click to show how the impossible dog house was actually built.
What makes our perceptual organization skills turn the structure on the right into… an impossible 3D figure?
Certainly, closure and continuity are part of what makes the boards look like they continue behind other boards and connect in places they really don’t (the board in the background), even though these connections and closures create an image of a house that violates our sense of how things can work in 3D space.

12. Visual Cliff: A Test of Depth Perception
Babies seem to develop this ability at crawling age.
No animation.
Instructor: as a preview of figuring out how we perceive depth, note that the pattern on the floor looks more condensed (and thus farther away) to the infant than the identical pattern on the table. The infant can perceive this difference as depth/height and see a danger of falling.
Note that the ability to perceive glass as solid does not appear to be as innate as the fear of the cliff.
Even newborn animals fear the perceived cliff.

13. Perceiving Depth: Binocular Methods
Unlike other animals, humans have two eyes in the front of our head. This gives us retinal disparity; the two eyes have slightly different views. The more different the views are, the closer the object must be. This is used in 3D movies to create the illusion of depth, as each eye gets a different view of “close” objects.
Click to reveal second text box.
How do we perceive depth from a 2D image?...
by using monocular (needing only one eye) cues

14. Monocular Cue: Interposition
Interposition: When one object appears to block the view of another, we assume that the blocking object is in a position between our eyes and the blocked object.
No animation.

15. Monocular Cue: Relative Size
We intuitively know to interpret familiar objects (of known size) as farther away when they appear smaller.
No animation.

16. Monocular Cues: Linear Perspective and Interposition
The flowers in the distance seem farther away because the rows converge. Our brain reads this as a sign of distance.
No animation.
Instructor: see if students can notice one other monocular cue for depth perception evident in this picture...interposition. The flowers in the very front (bottom of the frame) partially block the view of other flowers, and the whole hill of flowers appears to block the view of the hill in the background.

17. Tricks Using Linear Perspective
These two red lines meet the retina as being the same size
However, our perception of distance affects our perception of length.
Click to bring bottom line up.
The way our brain changes the perception of length in this case is called the Ponzo illusion, first demonstrated by Italian psychologist Mario Ponzo in 1913.
The two [rods/bars/logs] are the same size on screen, but our eyes tend to see one as larger because linear perspective makes its location on the train tracks seem farther away.

18. Monocular Cue: Relative Height
We tend to perceive the higher part of a scene as farther away.
This scene can look like layers of buildings, with the highest part of the picture as the sky.
If we flip the picture, then the black part can seem like night sky… because it is now highest in the picture.
Click to show bullets and example.

19. Monocular Cues: Shading Effects
Shading helps our perception of depth.
Does the middle circle bulge out or curve inward?
How about now?
Click to invert the image and show the hollow as a hill.

20. Light and shadow create depth cues.
No animation.

21. Monocular Cues: Relative Motion
When we are moving, we can tell which objects are farther away because it takes longer to pass them. A picture of a moon on a sign would zip behind us, but the actual moon is too far for us to pass.
No animation.
A great animated example can be found at
This depth perception cue is often referred to as motion parallax. It is used by many animals that don’t have the benefit of binocular cues because their eyes are on the sides of their heads. It is called “relative motion”; when we are moving, the objects we pass can appear to be moving in the opposite direction, and the farther objects don’t move as fast.

22. Perceptual Constancy
Our ability to see objects as appearing the same even under different lighting conditions, at different distances and angles, is called perceptual constancy. Perceptual constancy is a top-down process.
Examples:
color and brightness constancy
shape and size constancy
No animation.
Instructor: you can use this narrative to tie things together after the definition--“Because this means perceiving sameness even when receiving different sensory information, this means that we use this top-down process to change what colors, shapes, sizes and objects we think we see, depending on the context.”

23. Color Constancy
This ability to see a consistent color in changing illumination helps us see the three sides as all being yellow, because our brain compensates for shading.
As a result, we interpret three same-color blue dots, with shades that are not adjusted for shading, as being of three different colors.
Click to reveal bullets and animate example.

24. Brightness Constancy
On this screen, squares A and B are exactly the same shade of gray.
You can see this when you connect them.
So why does B look lighter?
Click to show image with gray bars to demonstrate.
Click to show image with gray bars connecting the A and B squares.
Hopefully, your students can explain that our brains compensate for shadows and other context by perceiving a constant color shade/brightness even when things are in shadow. This means mentally erasing the shadow to see objects in a lighter shade. This process, plus the checkerboard context, makes B seem lighter to our brain than the images sensed by our eyes.

25. Shape Constancy
Shape constancy refers to the ability to perceive objects as having a constant shape despite receiving different sensory images. This helps us see the door as a rectangle as it opens. Because of this, we may think the red shapes on screen are also rectangles.
Instructor: you could ask students an intentionally ambiguous question...“What shapes do you see outlined in red?” If they say “rectangle,” ask again, no longer referring to the doors. “Tell us the names of the red shapes.” Then click to fade the doors and reveal that the second and third red shapes are trapezoids.

26. Size Constancy
We have an ability to use distance-related context cues to help us see objects as the same size even if the image on the retina becomes smaller.
The Ames room was invented by American ophthalmologist Adelbert Ames, Jr. in 1934.
The Ames room was designed to manipulate distance cues to make two same-sized girls appear very different in size.
Click to reveal bullets and to show explanation.

27. Visual Interpretation: Restored vision, sensory restriction Experience shapes our visual perception
People have grown up without vision but then have surgically gained sight in adulthood. They learned to interpret depth, motion, and figure- ground distinctions, but could not differentiate shapes or even faces.
Animals raised at an early age with restrictions, e.g. without seeing horizontal lines, later seem unable to learn to perceive such lines.
We must practice our perception skills during a critical period of development, or these skills may not develop.
Click to reveal bullets.
Being blind between ages 3 and 46 cost Mike his ability to learn individual faces.

28. Perceptual Adaptation
After our sensory information is distorted, such as by a new pair of glasses or by delayed audio on a television, humans may at first be disoriented but can learn to adjust and function.
This man could learn eventually to fly an airplane wearing these unusual goggles, but here, at first, he is disoriented by having his world turned upside down.
Click to reveal bullets.

29. There’s more to Sensation and Perception than meets the eye
The Nonvisual Senses
There’s more to Sensation and Perception than meets the eye
Hearing: From sound to ear to perceiving pitch and locating sounds.
Touch and Pain sensation and perception
Taste and Smell
Perception of Body Position and Movement
No animation.

30. Hearing
How do we take a sensation based on sound waves and turn it into perceptions of music, people, and actions?
How do we distinguish among thousands of pitches and voices?
Click to reveal bullets.

31. Hearing/Audition: Starting with Sound
Length of the sound wave; perceived as high and low sounds (pitch)
Height or intensity of sound wave; perceived as loud and soft (volume)
Perceived as sound quality or resonance

32. Sound Waves Reach The Ear
The outer ear collects sound and funnels it to the eardrum.
In the middle ear, the sound waves hit the eardrum and move the hammer, anvil, and stirrup in ways that amplify the vibrations. The stirrup then sends these vibrations to the oval window of the cochlea.
In the inner ear, waves of fluid move from the oval window over the cochlea’s “hair” receptor cells. These cells send signals through the auditory nerves to the temporal lobe of the brain.
Click to show details about outer, middle, and inner ear.

33. The Middle and Inner Ear
Conduction Hearing Loss: when the middle ear isn’t conducting sound well to the cochlea
Sensorineural Hearing Loss: when the receptor cells aren’t sending messages through the auditory nerves
Cochlea hair cells
No animation.

34. Preventing Hearing Loss
Exposure to sounds that are too loud to talk over can cause damage to the inner ear, especially the hair cells.
Structures of the middle and inner ear can also be damaged by disease.
Prevention methods include limiting exposure to noises over 85 decibels and treating ear infections.
Click to reveal bullets.

35. Treating Hearing Loss
People with conduction hearing loss may be helped by hearing aids. These aids amplify sounds striking the eardrum, ideally amplifying only softer sounds or higher frequencies.
People with sensorineural hearing loss can benefit from a cochlear implant. The implant does the work of the hair cells in translating sound waves into electrical signals to be sent to the brain.
Click to reveal bullets.

36. Sound Perception: Loudness
Loudness refers to more intense sound vibrations. This causes a greater number of hair cells to send signals to the brain.
Soft sounds only activate certain hair cells; louder sounds move those hair cells AND their neighbors.
Click to reveal bullets.

37. Sound Perception: Pitch
How does the inner ear turn sound frequency into neural frequency?
Frequency theory At low sound frequencies, hair cells send signals at whatever rate the sound is received.
Place theory
At high sound frequencies, signals are generated at different locations in the cochlea, depending on pitch. The brain reads pitch by reading the location where the signals are coming from.
Click to reveal three text boxes.
Volley Principle
At ultra high frequencies, receptor cells fire in succession, combing signals to reach higher firing rates.

38. Sound Perception: Localization
How do we seem to know the location of the source of a sound?
Sounds usually reach one of our ears sooner, and with more clarity, than they reach the other ear.
The brain uses this difference to generate a perception of the direction the sound was coming from.
Click to reveal bullets.
Time differences as small as 1/100,000 of a second can cause us to localize sound. The head acts as partial sound barrier, creating a “shadow” in which sounds are delayed and not as loud (and possibly missing some higher frequencies).