Problem 1 - DONE

Question 1

perceptual processes

Answer 1

• journey from stimuli to responses

- continuously changing process

Question 2

7 steps of perceptual processes

Answer 2

1. environmental stimulus
2. light is reflected and transformed
3. receptor processes
4. neural processing
5. perception (knowledge)
6. recognition (knowledge)
7. action

Question 3

step 1 - environmental stimulus

Answer 3

what person observes (tree)

Question 4

step 2 - stimulus on receptors

Answer 4

light is reflected and transformed

Question 5

principle of transformation

Answer 5

stimuli and responses created by stimuli are transformed/changed between the environmental stimulus and perception
- central principle of perception

Question 6

first transformation

Answer 6

light hits object (tree) –> reflected from object to the person’s eyes

nature of reflected light depends on

• properties of the light energy hitting the tree
• properties of the tree
• properties of the atmosphere through which the light is transmitted

Question 7

second transformation

Answer 7

reflected light reaches the eye –> focused by the eye’s optical system –> form an image on the receptors of the retina

Question 8

step 3 - receptor processes/transduction

Answer 8

transduction = transformation of one form of energy to another form

receive light reflected from tree –> (1) transduction + (2) shape perception by the way they respond to stimuli

Question 9

step 4 - neural processing

Answer 9

neural processing = changes in signals that occur as they are transmitted through network of neurones

transduction –> electrical signals –> signals enter interconnected network of neurones –> retina –> out the back of the eye –> brain

Question 10

step 5 - perception

Answer 10

• person perceives object (tree)

- conscious awareness of object (tree)

Question 11

step 6 - recognition

Answer 11

• recognises object (tree)

- playing an object in a category that gives meaning

Question 12

step 7 - action

Answer 12

• action that involves motor activities

Question 13

knowledge

Answer 13

any information that perceiver brings to situation; acquired years ago or just recently acquired
- can affect a number of steps in perceptual processes

Question 14

bottom-up processing

Answer 14

(data-based processing)

• processing that is based on stimuli reaching the receptors
• stimuli provide starting point for perception
• -> everything that comes from the outside to the inside

Question 15

top-down processing

Answer 15

(knowledge-based processing)

• processing that is based on knowledge
• -> anything that we add (prior knowledge/experience/memory)

Question 16

method 1: measuring thresholds

Answer 16

• Gustav Fechner
• psychophysical methods
• -> absolute threshold
• Fechner’s law
• Ernst Weber
• -> difference threshold
• Weber’s law

Question 17

method 2: scaling - measure private experience

Answer 17

• S. S. Stevens
• -> magnitude estimation
• Stevens’ power law

Question 18

other methods to measure perception

Answer 18

• phenomenological method = person is asked to describe what he or she is perceiving or to indicate when a particular perception occurs
• visual search = observer’s task is to find one stimulus among many, as quickly as possible
• -> reaction time = time between presentation of the stimulus and the observer’s response to the stimulus

Question 19

Gustav Fechner

Answer 19

• German scientist-philosopher
• psychophysics = methods and theory to formally describe the relationship between sensation (mind) and the energy (matter)
• absolute threshold = minimum stimulus intensity that a subject can detect a given proportion of the time (50% or 75%)

Question 20

psychophysical methods

Answer 20

• how to measure an absolute threshold
• method of constant stimuli
• method of limits
• method of adjustment

Question 21

method of constant stimuli

Answer 21

• repeatedly present stimuli
• stimuli ranging from rarely to almost always perceivable
• stimuli are presented one at a time –> participants respond to each presentation ‘yes/no’, ‘same/different’
• weaknesses: time consuming, relies on subjects’ reports

Question 22

method of limits

Answer 22

• present stimulus far below/above threshold –> increase/decrease intensity until subject responds differently (reports detection/no detection of stimuli)
• weaknesses: time consuming, relies on subjects’ reports

Question 23

method of adjustment

Answer 23

• experimenter/observer adjust amplitude of a stimuli until observer can just barely detect the stimulus
• method of limits in which the subject can control the change

Question 24

Fechner’s law

Answer 24

• principle describing the relationship between the stimulus and resulting sensation
  –> says the magnitude of subjective sensation increases proportionally to the logarithm of the stimulus intensity
  y = k*log(S)
• began with Weber’s law
• calculation based on some assumptions about how sensation works
• assumes that all JNDs are perceptually equivalent –> incorrect
• indirect scaling = based on discrimination ability

Question 25

Ernst Weber

Answer 25

- German anatomist, physiologist - two-point touch threshold = minimum distance at which two stimuli are just perceptible as separate - difference threshold = JND (just-noticeable difference) = smallest detectable difference between two stimuli

Question 26

Weber's law

Answer 26

- principle describing the relationship between stimulus and resulting sensation --> says the JND is a constant ratio of the standard stimulus - Weber fraction = constant of proportionality in Weber’s law k = JND/S - involves clear objective measurement —> we know how much we varied the stimulus - observers can tell that the stimulus changed or they cannot

Question 27

S. S. Stevens

Answer 27

- psychologist - magnitude estimation = psychophysical method; participant assigns values according to perceived magnitudes of the stimuli --> ask observer to rate experience

Question 28

Stevens' power law

Answer 28

- principle describing the relationship between stimulus and resulting sensation --> says the magnitude of subjective sensation is proportional to the stimulus magnitude raised to an exponent estimation = k S^p - describes rating data quite well --> rating data are qualitatively different from the data that supported Weber’s law - can record the subjects’ ratings - direct scaling = have subjects produce numbers proportional to the magnitude of a given stimulus dimension

Question 29

how do we measure perception? lecture

Answer 29

1. psychophysics 2. electrophysiology 3. neuropsychology 4. cognitive neuroscience

Question 30

1. psychophysics lecture

Answer 30

stimulus --> perception - present a stimulus and determine the person’s response - first task (laws)

Question 31

2. electrophysiology lecture

Answer 31

stimulus --> brain processes - present a stimulus and measure direct brain activity - in animals (invasive) --> watch neural firing due to stimulus

Question 32

3. neuropsychology lecture

Answer 32

brain processes --> perception - study the effects of brain damage on behaviour - how does brain damage influence perception?

Question 33

4. cognitive neuroscience lecture

Answer 33

stimulus --> brain processes --> perception - present a stimulus and measure both brain activity and perceptual responses - fMRI (where in the brain?; passively measure) - EEG (when in the brain?) - TMS (local, temporary disturbance of brain function; actively measure)

Question 34

sensation

Answer 34

= process by which our senses (vision, hearing, smell, taste, touch) receive and relay outside stimuli - more basic level than perception not really perceive consciously

Question 35

perception

Answer 35

= way our brains organise and interpret sensory information and put it into context - consciously perceive something - active process - -> bottom-up processing - -> top-down processing