Intro to sensation and perception Flashcards
What is the goal of sensation and perception?
To find out about the external world
Define sensation
- Starting point
- Receiving info about the world via our senses through sensory receptor cells
How do we sense things?
- Sensory receptor cells
- These cells are sensitive to the physical properties of the world
Receiving info about the world via our senses through sensory receptor cells
Is this sensation or perception?
Sensation
Define receptor cells
Specialised neurones which respond to a particular physical property of environmental stimuli
Specialised neurones which respond to a particular physical property of environmental stimuli
What is this?
Receptor cells
You can hear the sound of a bell ringing
Is this sensation or perception?
Sensation
You can taste the sweetness of the strawberry
Is this sensation or perception?
Sensation
Define perception
- Ending point
- Our experience of the world
- Ending point
- Our experience of the world
Is this sensation or perception?
Perception
Is perception easy, complex or both?
Perception seems effortless but it is actually a very complex process
Why study perception? List 3 reasons
1) Perception is our only source of information about the world (everything we learn is learned through perception)
2) Perception underlies our interactions with the environment (we can only interact if we have the ability to perceive)
3) Perception allows for survival
What are the 3 practical reasons why we should study perception?
1) Understand change in ageing, disease, injury, etc.
2) Demands of driving, interacting with technology, etc (helps us learn why we can and cannot do certain things in certain circumstances)
3) Design of artificial perceptual systems
How do eye-witnesses recognise faces?
Is this sensation or perception?
Perception
Why do people drive too fast in fog?
Is this sensation or perception?
Perception
Why do crisps taste better when you hear a crunch?
Is this sensation or perception?
Perception
Why should psych UGs study perception?
Sensation and perception is the starting point for all psychological processes?
What are the 4 perceptual systems?
1) Vision
2) Audition
3) Touch
4) Smell and Taste
Define vision
Object identification/recognition, navigation and motion perception
Object identification/recognition, navigation and motion perception
Is this…?
a. Audition
b. Touch
c. Vision
d. Smell and Taste
c. Vision
Object identification/recognition, and object localisation
Is this…?
a. Audition
b. Touch
c. Vision
d. Smell and Taste
a. Audition
Object identification/recognition, and pain (detection of tissue damage)
Is this…?
a. Audition
b. Touch
c. Vision
d. Smell and Taste
b. Touch
Chemical detection/identification, and nutrition and poison avoidance
Is this…?
a. Audition
b. Touch
c. Vision
d. Smell and Taste
d. Smell and Taste
Define audition
Object identification/recognition, and object localisation
Define touch
Object identification/recognition, and pain (detection of tissue damage)
Define smell and taste
Chemical detection/identification, and nutrition and poison avoidance
List the perceptual process in order
- Distal stimulus
- Proximal stimulus
- Receptor processes
- Neural processing
- Action, Recognition, Perception
- Knowledge
Define distal stimulus
Physical object in the environment
Simply = Anything in the external world that you’re sensing
Physical object in the environment
What stimulus is this?
Distal stimulus
Define proximal stimulus
When info about the distal stimulus is received by the sensory receptor cells
Simply = Representation of distal stimulus
What stimulus is this?
When info about the distal stimulus is received by the sensory receptor cells
Simply = Representation of distal stimulus
Proximal stimulus
How does the proximal stimulus represent the distal stimulus?
Each sense receives info about the distal stimulus via a different type of environmental physical energy
e.g.
Distal = Bell ringing
Physical energy = Sound waves
Proximal = You can hear with your ear
What happens in the receptor processes?
Receptor cells carry out transduction
Receptor cells carry out transduction
Which process is this part of?
Receptor processes
Define transduction
Transformation of environmental physical energy into electrical energy in the nervous system
Transformation of environmental physical energy into electrical energy in the nervous system
This is known as…?
Transduction
When sound waves (physical energy) turns into electrical impulses, this is known as…?
Transduction
Describe what happens in vision during receptor processes
Receptors in the retina transform light into electrical impulses
Describe what happens in audition during receptor processes
Receptors in the inner ear transform sound into electrical impulses
In neural processing, how are electrical signal transmitted?
Transmitted from one neuron to the next
In neural processing, as neurons interact, what happens to the signal?
It changes
In neural processing, signal changes if…?
Neurons interact
In the perceptual process, what is perception?
Conscious sensory experience
Conscious sensory experience
What is this known as?
Perception
In the perceptual process, what is recognition?
Placing and object in a category
Simply = Understanding what the stimulus is, recognising it and putting it in a category
In the perceptual process, what is action?
Movement (i.e. movement of body, eyes)
Placing and object in a category
Simply = Understanding what the stimulus is, recognising it and putting it in a category
What is this known as?
Recognition
- You hear a ringtone ringing
- You are aware that the ringtone comes from a mobile phone based on knowledge of external world
Is this perception, recognition or action?
Perception
- You hear a ringtone ringing
- You are aware that the ringtone comes from a mobile phone based on knowledge of external world
- You recognise the ringtone because you use it
Is this perception, recognition or action?
Recognition
- You hear a ringtone ringing
- You are aware that the ringtone comes from a mobile phone based on knowledge of external world
- You recognise the ringtone because you use it
- You search through your bag because you believe the ringtone is yours and pick up the phone
Is this perception, recognition or action?
Action
Define visual form agnosia
An inability to recognise objects
Simply = You can perceive but can’t recognise objects
An inability to recognise objects
Simply = You can perceive but can’t recognise objects
This is known as…?
Visual form agnosia
What does visual form agnosia highlight about perception and recognition?
Distinction of perception and recognition
Movement (i.e. movement of body, eyes)
What is this known as?
Action
How does knowledge influence perception, recognition and action?
Existing knowledge, assumptions, memories and expectations can influence perception, recognition and action
Existing knowledge, assumptions, memories and expectations can influence perception, recognition and action
This effect of knowledge is known as…?
Top down processing
Define bottom up processing
Processing based on incoming stimulus in the environment/ sensory info
Define top down processing
Processing based on prior knowledge/ experience/ memories/ expectations
Perception involves what kind of processing?
Top down and bottom up
Why do we need top down processing?
Top down processing is important for helping us simplify the complex perceptual process
How does the distal stimulus differ from the proximal stimulus in the visual system?
- The distal stimulus is the actual physical stimulus in front of you
- The proximal stimulus is the very image that falls on the retina. It changes with changes in the position or lighting of the physical stimulus
What do we call the process of changing physical energy to electrical energy?
Transduction
What is the difference between perception and recognition?
Perception is consciously experiencing something in the world around us
Recognition is recognising a certain object and placing it in a particular category
What are the 2 approaches to studying perception?
1) Physiological
2) Psychophysical
Define physiological approach to studying perception
What’s going on in the brain and nervous system?
Define psychophysical approach to studying perception
What do we perceive? Or measures perceptual experience
Give 4 examples of the physiological approach to studying perception
1) Studying anatomy
2) Recording brain activity through single cell recording or imaging
3) Microstimulation
4) Lesioning and TMS
What are the 4 examples of imaging in order to record brain activity?
1) fMRI
2) MEG
3) EEG
4) PET
What does imaging look at?
Which parts of the brain are active during different tasks
What is micro stimulation?
Stimulate a part of the brain and see which parts are active when brain is stimulated
What is lesioning and TMS?
Creating temporary brain damage using magnetic fields that interfere with brain magnetic signals
What relationship does the psychophysical approach measure?
Relationship between physical world (stimulus) and psychological experience (perception)
What is in a typical visual psychophysics lab?
1) Visual stimulus on a computer screen
2) Stimulus is carefully controlled in terms of brightness, duration, etc
3) Participants sit at a controlled distance from the computer
4) Participants make judgements about what they see on the screen (brightness, colour, clarity, etc)
What are the 2 types of threshold in the psychophysical approach?
1) Absolute (detection)
2) Difference (discrimination)
What is absolute (detection)?
What is the smallest magnitude that we can perceive?
Simply = The smallest level of stimulus that can be detected, usually defined as at least half the time
e.g. The absolute threshold for hearing is the quietest sound you can hear
What is the smallest magnitude that we can perceive?
Simply = Measure limits of people’s psychophysical experience/perception
This is known as?
Absolute (detection)
What is difference (discrimination)?
What is the smallest difference that we can perceive?
Simply = We have 2 lights, and we have to detect the difference between the 2
So how bright does 1 light have to be in order for us to perceive it differently from the other light?
What is the smallest difference that we can perceive?
Simply = We have 2 lights, and we have to detect the difference between the 2
So how bright does 1 light have to be in order for us to perceive it differently from the other light?
What is this known as?
Difference (discrimination)
An experiment intends to measure how bright must a spot of light be to detect it
What does this measure?
Absolute threshold
What are the. 2 methods to measure absolute threshold?
1) Method of adjustment
2) Forced choice
What is method of adjustment when measuring absolute threshold?
Adjusting intensity of stimulus (e.g. increasing light levels) until participants can just perceive the target item
What is forced choice when measuring absolute threshold?
Forcing participants to choose an answer for all of the trials
Adjusting intensity of stimulus (e.g. increasing light levels) until participants can just perceive the target item
Which method is this?
Method of adjustment
What is the problem with method of adjustment?
People have different criteria for saying “yes I see it”
Simply = Some people wait until they’re really sure they see the target item before they tell the experimenter that they can see it
When measuring an absolute threshold, after plotting the results on a graph, what shape would the graph be?
stretched out ‘S’ shape
Psychophysical studies usually use a (large/small) number of participants, each doing (many/few) repetitions of each trial.
1) Small
2) Many
Define chance performance when measuring an absolute threshold by force
When participants end up choosing the correct answer during the first few trials (by chance/lucky guess)
What is a psychometric function?
A mathematical equation that plots the performance of a participant on a perceptual task against a physical aspect of a stimulus, such as contrast, size, or intensity
Performance is measured as a percentage of correct responses or responses where the participant could detect the stimulus.
Humans cannot hear sounds at very low or high frequencies
A (………….) can be used to show or predict the point at which a sound can be detected based on its frequency or other parameters.
Psychometric function
A mathematical equation that plots the performance of a participant on a perceptual task against a physical aspect of a stimulus, such as contrast, size, or intensity
Performance is measured as a percentage of correct responses or responses where the participant could detect the stimulus.
This is known as…?
Psychometric function
What % is considered the absolute threshold?
Absolute threshold taken as the intensity that gives 75% correct performance
Simply = When participants get the answer right 75% of the time, then that point is considered to be the limit of their ability to perceive/absolute threshold
Who translated human absolute thresholds into more meaningful quantities?
Galanter
What is the absolute threshold for vision, according to Galanter?
A candle flame seen at 30 miles on a dark, clear night
What is the absolute threshold for hearing, according to Galanter?
The tick of a watch under quiet conditions at 20 feet
What is the absolute threshold for taste, according to Galanter?
One teaspoon of sugar in two gallons of water
What is the absolute threshold for smell, according to Galanter?
One drop of perfume diffused into the entire volume of a three-room apartment
What is the absolute threshold for touch, according to Galanter?
The wing of a bee falling on your cheek from a distance of 1 cm
The wing of a bee falling on your cheek from a distance of 1 cm
This is the absolute threshold described by Galanter about which type of sense?
Touch
One drop of perfume diffused into the entire volume of a three-room apartment
This is the absolute threshold described by Galanter about which type of sense?
Smell
One teaspoon of sugar in two gallons of water
This is the absolute threshold described by Galanter about which type of sense?
Taste
The tick of a watch under quiet conditions at 20 feet
This is the absolute threshold described by Galanter about which type of sense?
Hearing
A candle flame seen at 30 miles on a dark, clear night
This is the absolute threshold described by Galanter about which type of sense?
Vision
Is difference (discrimination) a constant value/quantity?
No it is related to the baseline level
Difference (discrimination) is related to the baseline level. What does this mean?
How big of a difference the stimuli is from other things surrounding it
e.g. Adding a book to a bag of cotton wool vs. a bag of bricks
It is easier to detect that a book was added into a bag of cotton wool compared to a bag of bricks
Bricks and books weigh almost the same (little difference) whereas cotton is a lot lighter than books
The difference as a proportion of the baseline level is constant
What law does this follow?
Weber’s law
What does weber’s law suggest about perception?
The perception of change in any given stimulus is always dependent on what that stimulus is.
Simply = whether a change will be noticed is affected by how big, heavy or significant something was beforehand and how obvious the change is.
How different must two lines be to detect the difference?
Forced Choice – which line is shorter?
What type of threshold, following the psychophysical approach, is this?
Difference (discrimination)
What do the results of psychophysics highlight?
The relationship between the physical world and perceptual experience
Describe psychophysics (List 2 main aspects)
1) Psychophysics uses carefully controlled experiments to test perceptual performance
2) Results highlight the relationship between the physical world and perceptual experience
True or false?
We need to understand perception to understand how we interact with the world
True
True or false?
Perception only involves incoming sensory information (bottom-up)
False
Perception involves incoming sensory information (bottom-up) and prior knowledge and experience (top-down)
True or false?
Perception is a complex, single-stage process
False
Perception is a complex, multi-stage process
True or false?
There is only 1 approach to studying perception
False
Two main approaches to studying perception: physiological and psychophysical
True or false?
The two main approaches to studying perception are physiological and psychophysical
True
What are the 2 main approaches to studying perception?
1) Physiological
2) Psychophysical
