Chap1

Question 1

what is the differences between the psychophysics and neuroscience’s idea of perception?

Answer 1

Ø Early studies in * Psychophysics is the study of how physical stimuli are related or translated into psychological experience. Only studied the descriptive correlation whether it was linear or not. Neuroscience: Stimulus ->( causation) physiology -> (correlation)perception causation. We don’t know how physiology causes perception.

Question 2

absolute threshold ?

Answer 2

The minimum amount of stimulation that an organism can detect. Absolute threshold is defined as the intensity level at which the
probability of detection is 50%

Question 3

Gustav Fechner’s law vs Weber’s and Steven’s power law?

Answer 3

Weber’s Law: Just the noticeable difference is the constant proportion of the size of the initial stimulus.
Fechner’s Law: Subjective sensation is proportional to the logarithm of the intensity of the stimulus.
Ø S=K log R
Ø K= constant
Ø S= sensation (measure in JND)
Ø R = Reiz (stimulus)
Psycho = physical
Steven’s power law
Ø Modern investigators have found that Weber’s Law is not true for all senses.
○ EX: the perception of the opposite of what Fechner’s Law predicts. As shown in the graph, a slight increase in stimulus magnitude results in a great increase in perceived.
○ P= KSn
○ P= perceived magnitude
○ K= a constant
○ S= Stimulus intensity
○ When n is bigger than 1, response expansion
○ When n is smaller than 1, response compression?
○ Judgment of weight is the opposite with the Fechner’s law and the electric shock as well.

Question 4

methods to determine the threshold?

Answer 4

The method of limits: Ø The experimenter presents a stimulus in either increasing or decreasing intensity.
The participant indicates whether the stimulus is detected by choosing a YES/NO response
The method of adjustment: * The participant adjusts the intensity of a stimulus continuously (e.g., by turning a knob) until he/she can just barely detect the stimulus.
* The adjustment is in descending order and then in ascending order.
Method of constant stimuli (less biased)
* The intensities of the stimuli are presented in random order (rather than in ascending or descending order).
* The participant indicates whether the stimulus is detected by choosing a YES/NO response.
* The experimenter records the proportion of YES to NO responses at each level of intensity.

Question 5

what is grating acuity?

Answer 5

the smallest width of lines that the participants can detect.

Question 6

how to measure the grating acuity?

Answer 6

• Measuring grating acuity: participants are asked to indicate the orientation of a grating.
• Threshold: the smallest line-width at which the participant can still indicate the correct orientation
  (i.e., acuity)

Question 7

what is the oblique effect?

Answer 7

When grating acuity is assessed at different
orientations, the results show that acuity is best for gratings oriented vertically or horizontally.
Measuring perception: IV orientations, DV Relative detection sensitivity

Question 8

what the the methods to measure the perception above the threshold?

Answer 8

1. Magnitude estimation
2. Recognition testing (picture)
3. Reaction time
4. phenomenological report
5. physical tasks and judgments

Question 9

magnitude estimation?

Answer 9

§ Magnitude estimation (used by S.S.Steven to demonstrate the power law)
□ Level of intensity is randomly presented
□ Observer assign numbers to each stimulus
□ First stimulus is assigned an arbitrary number Further stimulus are assigned numbers representing the subjective

Question 10

Recognition testing?

Answer 10

□ Presenting a picture and ask what they see?
® The typical answer is “ houses near water and a boat”
® Phenomenological report: test of recognition, not a detail record of feelings
Words on computer are shown (35ms) and their task was to report the word. Some of the words has appeared earlier in a study phase, some had not. Recognition accuracy was measured. (the priming can have an effect as well)

Question 11

how the measuring Reaction time technique works?

Answer 11

□ Fix eye at the + sign in the middle of the screen but pay convert attention to A.
® A target appears anywhere at A or B, and participants should press a button when they detect the target
® Reaction time was shorter (faster)
® When the target appeared at A (compared to at B) the location where the participants were attending.

Question 12

phenomenological report?

Answer 12

□ Participants describe what they see. EX: what you and other person see the same thing from different sides. Piaget’s Three-Mountain Task.
Is more elaborated than the recognition task.

Question 13

describe the physical tasks and judgments?

Answer 13

□ Physical tasks
® Navigating through a maze
® Driving a car
□ Judgment
® Answering questions like:
◊ Are they the same or not? Testing child’s judgment skill
◊ What is the orientation of the lines?
◊ How far is an object from you?
◊ How much time has elapsed?
® Transduction
◊ Transforming environmental stimuli is transduced to the light/ electrical energy or neural activities.

Question 14

sensation vs perception vs transformation vs transduction vs transmission?

Answer 14

§ Sensation (transduction/ bottom-up/ processing of physical stimulus): Elementary Process that occur at the beginning of a sensory system.
§ Perception: conscious experience (awareness/ top-down) that occur near the end of the perceptual process. When we sense what happened (interpretations of the information)
§ Transformation: change in form change from 3D to 2D or neural activity (s -> R).
§ Transduction: sensory stimuli are converted to neural signal (R-N).
Transmission: transport of info from one neuron to another. Convergent of synapse (the change of info while transportation)

Question 15

Why Sensation Term is dropped?

Answer 15

□ Because it is very close meaning to transduction (having another term to mean the same thing is redundant). In everyday it is used to any sensation feeling.
□ Sensation is considered as an early part of the perceptual process, rather than a separate stage of processing.
It is hard to draw a line between sensation and perception.

Question 16

What are the two principle of perception?

Answer 16

Ø Principle of Transformation: When the stimuli and responses created by stimuli are transformed, or changed between the environmental stimuli and perception of these stimuli.
□ EX: ED distal stimulus -> 2D proximal stimulus -> neural processing
Ø Principle of representation: What a person perceived is based on the representation of a stimulus that is formed on the receptors (e.g., A proximal stimulus) and the resulting activity in the person’s nervous system (excitatory and inhibitory responses of neurons). Top-down processing of stimulus is different by anyone.

Question 17

what id neural processing?

Answer 17

Ø Neural processing: change that occur as signals are transmitted through a circuit of neurons.
§ Ex: neuron convergence (if the summation of the multiple inputs are strong, the synaptic pulse is intensify or the signal is amplify) and neural divergence.

Question 18

what is psychophysical parralism?

Answer 18

s the theory that mental and bodily events are perfectly coordinated, without any causal interaction between them. As such, it affirms the correlation of mental and bodily events (since it accepts that when a mental event occurs, a corresponding physical effect occurs as well), but denies a direct cause and effect relation between mind and body.