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1
Q

What is the Perceptual Process ?

A

The perceptual process begin with stimuli in the environment and ends with the behavioral responses of

  • perceiving
  • recognizing
  • taking action
2
Q

Principle of Transformation

A

Stimuli and the responses created by stimuli are transformed between environmental stimulus and perception

3
Q

Eye’s optical system

A
  • consists of the cornea + lens

–> they form a sharp picture of the stimulus on the receptors of the retina

4
Q

Principle of representation

A

Everything a person perceives is based on representations of stimuli that are formed on the receptors and the activity in the persons NS

5
Q

What are sensory receptors ?

A

Cells specialized to respond to environmental energy with each sensory systems receptors specialized to respond to a specific type of energy

ex.: visual receptors - light, auditory receptors - pressure changes in air

6
Q

Function of Visual receptors

A
  1. Transforming environmental energy into electrical energy (Transduction)
  2. Shaping perception by the way they respond to stimuli
7
Q

Transduction

A

Transformation of one form of energy to another form

8
Q

Visual pigment

A

Light sensitive chemical that reacts to light

  • found in visual receptors
  • transforms light into electrical energy
  • without it perception wouldn’t occur because the information about the representation of the stimulus in the retina wouldn’t reach the brain
9
Q

Function of the network of neurons

A
  1. Transmits signals from receptors (retina) to the brain
  2. Changes these signals because there are multiple routes with signals

a) traveling in the opposite directions
b) being amplified
c) being reduced or prevented from entering

10
Q

Primary receiving area

A

Receives signals from each sense

–> located in the cerebral cortex

11
Q

Which lobe can you assign to which sense ?

A

Occipital lobe –> vision

Temporal lobe –> hearing

Parietal lobe –> touch

Frontal lobe –> all senses, plays important role in coordination of information received from 2 or more senses

12
Q

Perception

A

Conscious awareness of the stimulus (active)

–> top down processing

13
Q

Recognition

A

Placing an object in a category, that gives it meaning

14
Q

Visual form of agnosia

A

Inability to recognize objects /

Perceiving parts of the object, but not being able to identify the whole object

15
Q

Action

A

Refers to the mere act of looking at different parts of the stimulus, no need to interact with it

–> usually involves motor activities

16
Q

Knowledge

A

Any information the perceiver brings to a situation

  • -> can affect a number of steps in the perceptual process
  • -> can be recently acquired information or acquired years ago
17
Q

Bottom up processing

A

Processing, that is based on stimuli reaching the receptors

–> ‘incoming data’

18
Q

Top down processing

A

Processing based on knowledge (Schemas)

19
Q

Psychophysical approach/

Psychophysics

A

Measures the relationship between the stimuli and behavioral response

–> presenting a stimulus and determining the persons response

20
Q

Oblique effect

A

There is a better detail vision for vertical and horizontal lines than slanted lines

21
Q

Physiological approach

A

Measures the relationship between

  1. Physiological responses + stimuli
  2. Physiological responses + behavioral responses

–> used to understand the physiology behind the oblique effect

22
Q

Absolute threshold

A

Describes the minimum stimulus intensity that can just be detected

ex.: Vision –> the smallest line that can barely be seen

–> threshold is lower (finer lines can be seen) when the lines are horizontal/vertical

23
Q

Human perception is variable.

How can this affect measurements ?

A

Measurements at one point in time can differ slightly from measurements at another point.

24
Q

Method of limits
(Classical psychophysical method)

Fechner

A

Experimenter presents stimuli by either ascending or descending order

  • -> threshold is the average of all crossover points
  • -> increasing or decreasing intensity
25
Q

Crossoverpoint

A

The change/ Point when the observer goes from perceiving the stimulus to not perceiving it anymore or vice versa

ex.: hearing a sound –> not hearing it anymore

–> may vary slightly, procedure is therefore repeated

26
Q

Method of adjustment
(Classical psychophysical method)

Fechner

A

Observer increases/decreases stimulus intensity until the stimulus can just be detected

–> fastest method because the observers can just adjust their threshold quickly

27
Q

Method of constant stimuli
(Classical psychophysical method)

Fechner

A

Experimenter presents 5 to 9 stimuli with different intensities in a random order

–> threshold is the intensity that results in detection on 50% of the trials

–> most accurate method, but time consuming

28
Q

Difference threshold

A

Describes the minimum difference that must exist between 2 stimuli before we can tell the difference between them

–> Differenze Limen (DL)

29
Q

Weber fraction

A

The ratio of DL vs Standard always corresponds to a certain percentage

ex.: weight = 0.02

–> each type of sensory judgment has its own weber fraction

30
Q

Weber law

A

The weber fraction remains the same as the standard is changed

ex.: if the weight is doubled, DL is doubled too

31
Q

Magnitude estimation

Stevens

A

Measuring the relationship between the stimulus + perception of its magnitude

32
Q

Response compression

A

Increase in perceived magnitude is smaller than the increase in stimulus intensity

ex.: doubling the intensity of brightness doesn’t necessarily double the perceived brightness

–> exponent < 1.0

33
Q

Response expansion

A

As the intensity is increased, the perceptual magnitude increases more than the intensity

ex.: small increases in electric shock will result in large increases in pain

–> exponent > 1.0

34
Q

Stevens Power law

A

Perceived magnitude = a constant x stimulus intensity , raised to a power

P = KS^n

35
Q

Visual research

A

Method in which the observer has to find one stimulus among many, as quickly as possible

ex.: recognizing face in a crowd

36
Q

Response criterion

A

Determines how and why we respond the way we do and therefore influences the threshold measurement

ex.: wanting to be totally sure before responding –> response is more conservative

–> every person has a different response criterion

37
Q

Sensation

A

The act of unconsciously perceiving something (passive)

  • -> bottom up processing
  • -> step before actively perceiving
38
Q

Electrophysiology

A

Presenting a stimulus and measuring the brain activity

–> done with animals

39
Q

Neuropsychology

A

Studying the effects of brain damage in behavior

40
Q

Which scanning techniques can be used to measure perception ?

A
  • fMRI
  • EEG
  • TMS
41
Q

Prosopagnosia (Face blindness)

A

Inability to recognize faces, but normal vision

–> lesion the ‘fusiform face area’ ( region of the IT cortex )

42
Q

What are the basic stages of the ‘Perceptual process’ ?

A
  1. Environmental stimulus
  2. Light is reflected and transformed
  3. Receptor processes
  4. Neural processing
  5. Perception
  6. Recognition
  7. Action
43
Q

Stage 1

Environmental stimulus

A

The person is observing the tree

44
Q

Stage 2

Light is reflected and transformed

A
  1. Persons perception of the tree is based on the light reflected from the tree
  2. Eyes optical system transforms the stimulus into a sharp image on the receptors to the retina
45
Q

Stage 3

Receptor processes

A

The visual receptors transform the environmental energy into electrical energy with the help of visual pigments

–> Transduction

46
Q

Stage 4

Neural processing

A
  1. The tree is represented by electrical signals in the visual receptors
  2. Signals enter a complex network of neurons
  3. Signals then travel to brain
47
Q

Stage 5

Perception

A

Electrical signals have reached the brain and are transformed into conscious experience

–> Person actively perceives the tree

48
Q

Stage 6

Recognition

A

The person recognizes the stimulus, placing it into the category ‘tree’

49
Q

Stage 7

Action

A

The person might then take action by merely looking at different parts of the tree / looking closer

50
Q

When do the laws not apply ?

A
  1. Stevens law always applies
  2. Fechner’s law doesn’t when the exponent is > 1
  3. Webers law doesn’t when the exponent is < 1