Chapter 1 - Introduction to Perception

Question 1

1- Name the 7 steps of the perceptual process.

Answer 1

1. Stimulus in the environment
2. Light is reflected and focused
3. Receptor processes
4. Neural processing
5. Perception
6. Recognition
7. Action

Question 2

2- What is a distal stimulus vs. a proximal stimulus?

Answer 2

Distal Stimulus:
* Environmental stimuli are all objects in the environment that are available to the observer.
* Observer selectively attends to objects.
* Stimulus impinges on receptors resulting in
internal representation.

Proximal Stimulus:
* The representation of the distal stimulus on the receptors.
* Stimulus is “in proximity” to the receptors

Question 3

3- Describe steps 1 and 2 of the perceptual process. What is the principle of transformation?

Answer 3

• Step 1: Distal stimulus: Information about the tree (the distal stimulus) is carried by light.
• Step 2: Light is reflected and focused:
  The light is transformed when it is reflected from the tree, when it travels through the atmosphere, and when it is focused on by the eye’s optical system.
  The result is the proximal stimulus, the image of the tree on the retina, which is
  a representation of the tree.

Principle of transformation:
* When the stimuli and responses created by stimuli are transformed, or
changed, between the environmental
stimuli and perception.

Question 4

4- Describe step 3 of the perceptual process.

Answer 4

Step 3: Receptor processes:
* Sensory receptors are cells
specialized to respond to
environmental energy.
* Visual pigment is what reacts to light.
* Transduction occurs, which changes environmental energy to nerve
impulses.
* The end result is an electrical representation of the tree.

Rod and cone receptors line in the back of the eye. They change light energy into electrical energy.

Question 5

5- Describe step 4 of the perceptual process.

Answer 5

Step 4: Neural Processing:
* Neural processing - changes that occur as signals are transmitted through the maze of neurons
Primary receiving areas:
* Occipital lobe= vision
* Temporal lobe=hearing
* Parietal lobe=skin senses

Question 6

6- Describe steps 5 to 7 of the perceptual process.

Answer 6

Step 5: Perception:
* Electrical signals are
transformed into
conscious experience.
* Person perceives object
(e.g.,a tree). “I see something”

Step 6: Recognition:
* Person recognizes it as a
tree (places object in
category). “It’s an oak tree”

Step 7: Action:
Behaviour. “Let’s have a closer look”

Question 7

7- Explain knowledge, bottom-up processing and top-down processing.

Answer 7

Knowledge: any information the perceiver brings to a situation.

Bottom-up processing:
* Processing based on incoming stimuli from
the environment
* Also called data-based processing

Top-down processing:
* Processing based on the perceiver’s previous knowledge (cognitive factors)
* Also called knowledge-based processing

Question 8

8- Name the 3 different relationships between the stages of the perceptual process. Give examples.

Answer 8

Observing perceptual processes at different stages in the system:

• Relationship A: the stimulus (proximal, distal)-perception/behaviour (perception, recognition, action) relationship
  Ex: Decreasing intensity difference between dark and light bars until subjects
  could no longer detect the gratings
• Relationship B: the stimulus (proximal, distal)-physiology (receptors, processing) relationship
  Ex: bigger brain response to vertical and horizontal orientations, measured with optical imaging. Optical imaging: Electrical activity of neurons is related to local
  metabolic activity and blood flow. Correlates with brain activity
  *Blood volume changes
  *Blood oxygenation changes
  *Light scattering changes caused by ion
  and water movement
  -relative fMRI amplitude and relative detection sensitivity
• Relationship C: the physiology (receptors, processing)-perception/behaviour (perception, recognition, action) relationship
  ex: Decreasing intensity difference between dark and light bars until subjects
  could no longer detect the gratings

Question 9

9- Describe the method of limits to measure perception.

Answer 9

Absolute threshold = the smallest amount of energy needed to detect a stimulus

Method of limits:
* Stimuli of different
intensities presented in
ascending and
descending order.
* Observer responds to
whether she perceived the
stimulus.
* Cross-over point is the
threshold.

(see graph)

Question 10

10- Describe the method of adjustment to measure perception.

Answer 10

Ex: adjust the volume until you can just barely hear the sound. (read more in book)

Question 11

11- Describe the method of constant stimuli to measure perception.

Answer 11

?? See description in book

Question 12

12- Explain the difference threshold.

Answer 12

Ex: electric shock vs. light intensity.
To feel the augmentation of intensity of an electric shock, you have to augment it by 0.1 only. To feel the augmentation of intensity of light, you have to augment it by 0.8.
(see textbook)

Question 13

13- Explain the magnitude estimation and the power function.

Answer 13

?? see graph and textbook