Sensation and Perception Flashcards
sensation
process of receiving physical stimuli on receptors and then turning it into electrical signals in neurons
perception
process of organizing and interpreting information to give it meaning
bottom-up processing
like “entering data” into a computer, it’s when information starts at receptors and then goes up to the brain to get integrated
integration
putting things together, building up
top-down processing
like a “program” in a computer, it’s when established mental processes organize and interpret the information
What are the differences between sensation and perception?
- sensation = bottom-up, perception = top-down
- sensation = objective, perception = subjective
- sensation = entering data, perception = organizes data
- perception uses past experiences, sensation does not
absolute threshold
minimum stimulation needed to detect a stimulus at all, e.g. minimum volume to hear song on telephone
difference threshold
minimum difference between competing stimuli to be able to notice there is a difference, e.g. minimum difference between two sounds to be able to tell which is louder
just noticeable difference
the point where two stimuli are different enough to be able to tell them apart from one another
priming
when you tell someone to expect a certain outcome, which then affects their perception
signal detection theory
a theory that tries to explain what factors affect our ability to detect stimuli if there is background noise
Which factors affect our stimulus detection thresholds?
- experience
- expectations
- motivation
- tiredness
Give an example of an absolute threshold and of a difference threshold.
- absolute threshold of hearing = volume that you need to turn your phone up to to hear a song
- difference threshold = difference between volumes of two phones in order to tell which one is louder
How can people’s perceptions be manipulated?
they can be given information about, like different labels on and different descriptions of, bottles of water, and asked to describe the differences between them, they say they do actually sense a difference in the taste even though they are the same bottle of water
What happens as you increase the strength of a stimulus?
- below the absolute threshold, there is no perception
- as you increase it past the absolute threshold, there is perception of greater detail
- past a certain point, the signal becomes distorted, and we perceive less detail
distortion
when detail of a signal cannot be perceived
subliminal stimulus
when the strength of a signal is below the absolute threshold of perception
What evidence is there that subliminal stimuli can affect our behaviour?
- definitely possible
- but only to a modest degree
- and under certain circumstances
- e.g. people have to already be wanting that thing
- e.g. iced tea
Give two examples of the difference between sensation and perception.
- images are sensed upside-down (image is flipped on the receptors in the eye), but brain flips it back up so we perceive “right side up”
- there is a blind spot when we sense visual information where we can’t see, but our brain fills it in for us so we perceive without a hole in our vision
Give an example of how we know perception is subjective.
- when asked to count the number of letters ‘f’ in a phrase after reading it out loud, people will say fewer than the actual number because ‘f’ has a ‘v’ sound at the end of words like “of”
Give examples of when your brain adds information as part of perception.
- people will see a triangle that is not actually there when shown a picture of circles with pieces cut out of them
closure
when our brain fills in gaps when there are “disparate pieces of data”, that is pieces of data that look like they should go together in a certain arrangement
Why is the subjectivity of perception important?
closure causes us to create information that is not there, come up with a false narrative, and therefore make incorrect conclusions, like thinking something is there when it is not
What is an “ambiguous image”?
a drawing that looks to be one thing for some people but a different thing for other people
What is the significance of ambiguous images?
it means perception is subjective
Why do we perceive differently?
prior experience shapes tendencies to perceive things in our own unique way?
What is the main reason that perception is subjective?
selective attention
selective attention
focussing awareness only on a particular stimulus
What is an example of an experiment to show that selective attention affects perception?
“Necker cube”: show someone a certain picture of a cube and they will be able to perceive cubes facing different ways depending on where they focus their attention; if the cube is made of holes it can also look as if it behind a board
What is the Necker cube and what does it show?
- when you arrange circles with lines through them so that you perceive a cube, you can actually perceive four different cubes that you can perceive depending on where you focus on your attention
- this shows that perception is subjective due to selective attention
change blindness
when we are watching something, this can distract us so that we don’t notice changes that are happening right in front of our faces
Give an example of an experiment that shows change blindness.
- guy giving directions doesn’t notice that the guy has changed with the other guy when a board goes by
- this is because the guy giving directions is not paying attention to the guy
Is people using devices and driving safe?
- no, because their attention is being diverted
- we cannot maintain full attention while doing multiple things
- our perception is changed by diverting our attention
gestalt
tendency to integrate pieces of information into a meaningful whole
Gestalt Theory
the theory that we group information together using a grouping principle to make a complete group, which is the reason that we saw a triangle when there was none in one of the optical illusions
What are some examples of grouping principles?
- proximity = grouping nearby things together
- similarity = grouping similar things together
- continuity = perceiving continuous patterns
- connectedness = grouping connected things together
- closure = filling in gaps
Give two examples of perceptual constancy
- if you see someone from far away even though they look smaller you still understand how big they actually are
- when you open a door even though it looks thinner and taller you still perceive it to be the same door that is just moving
perceptual constancy
when we perceive something as continuing to be a whole object even though the way it looks changes
perceptual set
a tendency to perceive certain things when presented with certain stimuli
schema
mental framework in which we interpret incoming information
Why are schemas important?
- since schemas affect the way we perceive things, negative schemas can make us interpret events more negatively, which is one cause of depression
- therefore schemas can be altered in order to retrain the way we think, as a treatment for depression
- this is the basis of cognitive behavoiural therapy
Give an example of a perceptual set.
- words that sound alike: folk, croak, soak
- now if you say them next to each other then when you are asked a question like “what’s the white stuff in eggs” you will answer incorrectly and say “yoke”
- you are grouping the words together, and based on Gestalt Theory and closure you will fill in any gaps to make a complete whole
parallel processing
when we simultaneously (at the same time) process multiple aspects of a stimulus
How do we visually process information?
using parallel processing we process four aspects of visual stimulus at the same time:
- colour
- motion
- form
- depth