Sensation and Perception 2009-2010


Sensation and Perception 2009-2010

Chapters In Textbook:

  • Chapter 5
  • Chapter 6

Assignments:

  • Outline Chapter 5 & 6
  • Sensation & Perception WS
  • In Depth - Perception
  • PsychSim: Visual Illusions
  • PsychSim: Auditory System
  • Myers Quizzes 5.1, 5.2, 6.1, 6.2

Topic Summaries (if available):

Key Terms:

Quizlet(s): Chapter 5, Chapter 6

Test Information:



07. Draw and label a detailed picture of an eye. Then explain in writing how an eye receives information and transmits it to the brain. Finally, explain depth perception.
08. Draw and label a detailed picture of an ear. Then explain in writing how an ear receives information and transmits it to the brain. Finally, explain how we hear pitch, how we locate sounds, and the different types of hearing loss.
09. Explain selective attention, the different ways our mind groups stimuli, and perceptual constancy. Use examples.


Questions received via email:

Q: I was reading barrons and it stated that the pupil is like a shutter of the camera? How so? Does the pupil just receive the light after the light goes through the cornea?
A: While I'm not an expert on cameras, I think Barron's might be a bit off on this one. The pupil is the "hole" in your eye. Light passes through this hole and land on the retina. The size of the hole is determined by the iris, a muscle which makes the hole (the pupil) bigger or smaller, controlling the amount of light which enters the eye.

Q: Do both the lens AND cornea focus the light? They just do it at different times?
A: Yes, the lens and the cornea are involved in focusing light. The cornea actually does 2/3 of the work, but it's focus is fixed. The lens does the other 1/3* of the work, but it's focus is adjustable. So light passes through the cornea is gets focused a bunch, and then passes through the lens which finishes the job while adjusting the focus so it hits the retina properly. *Note - there is another part of the eye called the vitreous that also plays a part in focusing light, but we don't really need to worry about it.

Q: Also, the impulses from the left side of the retina go to the left hemisphere, and vice versa, the impulses from the right side go to the right hemisphere. However, where do the impulses in the optic chiasm go (which hemisphere?)
A: Think back to our example of the cyclops with a split brain. He has one eye only. Any image that falls on his left visual field is sent to the right hemisphere and vice versa. All visual stimulus passes through the optic chiasm, which is just a fancy term for where the optic nerves partially cross. It's the same for people with two eyes and a non-split brain. Check out Figure 2.26 on page 86 or Figure 5.9 on page 204of the text.

Q: Is the organ of Corti in the ear just a bunch of neurons? Are there types of neurons in the ear that go to the auditory nerve?
A: The organ of Corti (named after some dude who's last name was Corti) is a series of rows of small hairs located on the basilar membraine in the cochlea. The place along the basilar membrane where maximum excitation of the hair cells occurs determines the perception of pitch according to the place theory. The perception of loudness is also connected with this organ. The hairs vibrate when they detect a sound, and these vibrations tigger impulses in nerve fibers (neurons) which combine to make the auditory nerve (a bunch of neuron axons).

Q:Lastly, so pitch works by BOTH the frequency and place theory, just like the trichromatic and opponent-process theory work together?
A: Yes, the two theories work together. The place theory best explains how we hear high-pitched sounds and the frequency theory best explains how we hear low-pitched sounds. Some combination of the two explains the mid-ranged sounds.

Q: Hi, I wanted to ask you a question about the test.In one of the FRQ questions that asks us about defining how our optic system works, do we need to explain how the visual information processing works as well? Such as the feature detectors etc. Or would it be okay to just draw and label the process of vision, and write out in words the steps of how we perceive light?
A: Here's the question, "Draw and label a detailed picture of an eye. Then explain in writing how an eye receives information and transmits it to the brain. Finally, explain depth perception." So the first part is how the eye itself works (sensation question), and the next part is how we see depth (perception question), you know, monocular and binocular cues. Feature detectors don't really fit in this one. The last sentence of your question covers the first part of the question. Just add it the depth perception.

Q: I had another question! This is about the middle ear. The definition of a middle ear says that it is a chamber between the eardrum and cochlea containing three tiny bones, (now here comes the part I don't understand) that concentrate the vibrations of the eardrum on the cochlea's oval window. Does the "concentrate the vibrations" mean amplify the sound? Or store the sound? I thought the middle ear was just connecting the outer ear and inner ear and being the bridge to send the sound waves.
A: For our introductory purposes, "just connecting the outer ear to the inner ear" works. :-) If however, you want to get technical (which we don't need to do), here's what I found on wikipedia:
"The ossicles are classically supposed to mechanically convert the vibrations of the eardrum, into amplified pressure waves in the fluid of the cochleainner ear) with a lever arm factor of 1.3. Since the area of the eardrum is about 17 fold larger than that of the oval window, the sound pressure is concentrated, leading to a pressure gain of at least 22. The eardrum is fused to the malleus, which connects to the incus, which in turn connects to the stapes. Vibrations off the stapes footplate introduce pressure waves in the inner ear. There is a steadily increasing body of evidence which shows that the lever arm ratio is actually variable, depending on frequency."
So yes, it appears that the tiny bones (ossicles) do amplify, or concentrate, the vibrations. Sounds like an issue for a physics class. :-)

2009-2010 Test 3 MC Answers are attached below. :-)

Miscellaneous Information: