Chapter 5 - Sensation & Perception

Question 1

Describe the difference between bottom-up and top-down processing.

Answer 1

Bottom-up: perception based on physical attributes of the stimulus.

Top-Down: perception based on prior knowledge and expectations of the stimulus.

Question 2

What is an absolute threshold?

Answer 2

The minimum intensity of stimulation that must occur before you experience a sensation 50% of the time.

Question 3

What is a difference threshold?

Answer 3

The smallest difference between two stimuli that you can notice.
ex: you hear a tone, then you notice an increase in the tone’s volume.

Question 4

What is Weber’s law?

Answer 4

The difference threshold is proportional to the original threshold of the stimulus (if you have a 1 oz feather and a 2 oz feather, the difference is more noticeable, than a 5 pound rock and 5 pound and 1 oz rock)
- the more intense the stimulus, the higher the difference threshold

Question 5

What are the four possible outcomes in a trial of a signal detection experiment? How could response bias affect these outcomes?

Answer 5

Hit
Miss
False Alarm
Correct Rejection

Question 6

In audition, what characteristics of the sound wave determine intensity/loudness and pitch?

Answer 6

• Amplitude
• Frequency

Question 7

How are sound waves converted into neural activity in the brain?

Question 8

What is temporal coding vs. place coding?

Question 9

How do humans localize sound?

Question 10

Describe the two different types of nerve fibers for pain.

Answer 10

Fast fibers - sharp, immediate pain (ex: touch a hot skillet)
Slow fibers - chronic, dull, steady pain (ex: tingly feeling your hand has after you burned it, keeps us from using the injured body part)

Question 11

Explain the gate control theory of pain.

Answer 11

We experience pain when pain receptors are activated and a neural “gate” in the spinal cord allows the signals through to the brain. Sometimes, sensory nerve fibers can “close a gate” and prevent or reduce the perception of pain.

Question 12

How are sensation and perception different?

Answer 12

Sensation - the detection of physical stimuli. (ex: you smell something in the hallway)
Perception - the process by which the brain organizes and interprets the sensory information that is detected. (ex: you interpret the smell as pizza)

Question 13

What is sensory coding?

Question 14

Explain the basic process of sensory adaptation and give an example.

Answer 14

Sensory adaptation is when there is a disappearance of sensory responsiveness when stimulation is unchanging (not a threat).
ex: The air conditioner has been on for half an hour while you are studying that you do not notice the sound anymore.

Question 15

Know the basics regarding the stimulus for vision (light) – i.e., what characteristics of light determine what we see?

Question 16

What does the sclera do?

Answer 16

The white visible part of your eyes. It reflects light back out.

Question 17

What does the cornea do?

Answer 17

Does about 2/3 of the eye’s focusing. Some incoming light comes through the cornea.

Question 18

What does the iris do?

Answer 18

Makes eyes the color they are. Controls how dilated the pupil is.

Question 19

What does the pupil do?

Answer 19

The pupil allows some incoming light and its the opening of the lens.

Question 20

What do the lens do?

Answer 20

Does the rest of the eyes’ focusing. Does so by changing the shape to focus incoming light rays (accommodation).

Question 21

What does the retina do?

Answer 21

Located at the back of your eyeballs, has rods and cones which turn light into neural signals

Question 22

What do the rods and cones do?

Answer 22

Rods and cones are receptor cells.

Question 23

What do the bipolar cells do?

Answer 23

Bipolar cells send sensory information to ganglion cells.

Question 24

What do the ganglion cells do?

Answer 24

The axons of the ganglion cells form the optic nerve.

Question 25

What is the optic nerve?

Answer 25

The optic nerve exits the eye at the back of the retina to the brain (thalamus).

Question 26

What is the blind spot?

Answer 26

You cannot see in this spot, there are no rods and cons.

Question 27

What is the fovea?

Answer 27

Near the retina’s center where cones are densely packed.

Question 28

What are the differences between rods and cones?

Answer 28

Rods
- 120 million rods
- primarily used for night vision (high sensitivity)
- don’t support color vision
- not good for fine details
- located at the periphery of the retina

Cons
- 6 million cones
- primarily used for vision under brighter conditions (during the day) (low sensitivity)
- support color vision
- located near the center of the retina (fovea)
- good for detail

Question 29

What causes nearsightedness and farsightedness?

Answer 29

Nearsightedness - By the time light hits your retina, the image is blurry because the light comes into focus too soon.
Farsightedness - When light hits your retina it is blurry because the light would come into focus farther than where your retina is

Question 30

What is a feature detector?

Question 31

Explain the trichromatic theory of color vision and the opponent-process theory and how both contribute to our understanding of color perception.

Answer 31

Trichromatic Theory - color vision results from activity in three types of cones. blue- violet (short), yellow- green (medium), red-orange (long). If you stimulate a combination of them, that is how you get other colors.

Opponent-Process Theory - this theory treats pairs of colors as opposing. red/green, blue/yellow, black/white. If we stare at something green for too long, we wear out our green receptors, so then we see sa red afterimage, because our red receptors are not fatigued

Question 32

Explain why afterimages occur.

Answer 32

The opponent-process theory explains afterimages. Afterimages occur when one type of receptors are fatigued (eg. green) so you see it’s opponent for a few seconds when you look away (eg. red)
- green flag
- blue lady

Question 33

Define proximity.

Answer 33

Near each other seen as one thing

Question 34

Define closure.

Answer 34

What your mind does when there are incomplete boarders.
ex: we perceive a circle with a gap as a complete circle

Question 35

Define similarity.

Answer 35

When two stimulus objects resemble each other seen as one thing

Question 36

Define good continuation.

Answer 36

We tend to group
ex: when lines intersect, we tend to group them to form continuous lines with minimal changes in direction

Question 37

Common Fate

Answer 37

When stimulus elements move in the same direction at the same speed we see them as part of one object