Perception Flashcards
The differerence between senstation & perception. Visual illusions.
What is the sensation
physical stimulation of the sensory receptors by the environment, seeing, hearing etc. Brain interprets the information leading to perception.
What is Perception
Organisation and and interperpretation of sensory info.
difference between sensation and perception
sensation the detection of stimulus
perception the interpretation of it
Ponzo illusion
illusion, converging lines give illusion of distance, misinterpreted depth cue
Muller-Lyer
Arrows change perception of lenght of the line. misinterpreted depth cue
What is a Kanizsa Triangle
fiction
What is Rubins vase an example of
Ambiguous figure
name three depth cue illusions
Ames room
Ponzo illusion
Muller-Lyer illusion
What is an ambiguous picture
one that can be seen in two ways
Explain how depth cues are misinterpreted
the brain sees the linear perspective and mistakenly applies the rule of size constancy
what is size constancy
the brains ability to perceive familiar objects as the same size, despite changes in size of the image on the retina.
Name a direct theory of perception
James Gibson’s
What theory did Gibson have abt perception
Gibson’s direct theory of perceptions
Define Gibsons direct theory of perception
Gibsons direct theory says: The visual information we see gives us everything we see to understand what we are looking at, we don’t need to rely on past experience.
What are the element of Gibsons direct theory
Elements of Gibsons direct theory:
1. optic array receives all the information needed for perception, light, texture, movement and depth.
- Usual binocular and monocluar depth cues.
Plus: monocular Optic flow patterns - speed/direction
and Motion parallax speed.
- that perception is innate.
What are optic flow patterns
The point we are moving towards stays static whilst the things are passing rush away from it. This gives us the information to judge how fast and in what direction. no flow then we are not moving.
Motion parallax
things nearer to us appear to move faster than those further away.
what are binocular depth cues
cues detected by both eyes
What are the two binocular depth cues
Retinal disparity
Convergence
what is the binocular depth cue retinal disparity
Way we judge distance; because the eyes are abt 6 cm apart the brain receives two images. The closer the object the bigger the difference in the images and the further away the less difference.
What is the binocular depth cue convergence
A way to judge distance: When an object is coming towards us our eyes come together. The muscles around the eyes work harder the more they come together, this muscle information give the brain the cue about depth and distance.
what are monocular depth cues
cues that can be used with one eye.
name the monocular depth cues
- Height in plane
- Relative size
- Occlusion
- Linear perspective
What does the monocular cue “height in plane” mean
Objects higher up in the visual plane appear further away.
What does the monocular cue “relative Size”mean
the object of something close by will appear bigger that one in the distance, even though we may know that they are the same size.
What does the monocular cue “occlusion” mean
objects hidden behind another are assumed to be further away.
What does the monocular cue “linear perspective” mean
Parallel lines, such as a road or railway, the further you look along them into the distance the closer the lines appear to converge.
What does the influence of nature mean to Gibson’s direct theory.
We don’t need to learn anything to perceive the world around us it is innate
Gibsons direct theory evaluation
Evaluation of Gibsons direct theory:
+ real life, research with pilots during WW2.
+ struggles to explain illusions, if we “know” everything from the information in front of us how can illusions work. Our brains do make perceptual errors.
+ support for the role of nature: Babies walking off a cliff experiment.
Who’s was the constructivist theory of perception
Richard Gregory
What is Gregory’s constructivist theory
Gregory’s constructivist theory: Perception is a construction using inference, visual cues and past experience, ie nuture that out understanding of visual cues are learned and not innate. .
Evaluation of Gregory’s constructivist theory
Gregory’s constructivist theory evaluation:
+ research in different cultures: many studies that show that people in different cultures interpret visual cues differently so that must of been learned and not innate. Hudson.
- visual illusions, supported by Gregory’s theory however, these illusions are made to fool us and may not explain how perception works in the the real world.
- Doesn’t explain how perception gets going in the first place, studies with babies shown human faces and random patterns, the babies preferred the faces so some perception must be innate.
Name and study into Perceptual Set and Culture
William Hudson
What is perceptual set
tendency or readiness, because of culture, motivation, expectation or emotion, to notice certain aspects of sensory environment whilst ignoring others.
Hudson study of Perceptual Set and Culture. Aim, method, results and conclusion.
Hudson Perceptual set and culture study:
Aim. To see if people from different cultures interpret information in a picture differently.
Method:
2d drawings of an antelope, an elephant and a man with a spear shown to four groups
Native South Africans, schooled and unschooled
White Europeans schooled and unschooled.
There were three questions: What do you see, What is the man doing and Which figure is nearer.
Results:
Many people said the elephant.
Black and white schooled participants more likely to perceive depth than unschooled.
White schooled participants were more likely to perceive depth than the black schooled participants.
Conclusion:
Results suggest that different culture perceive depth cues differently on a 2d picture.
One cultural difference was schooling. More familiar with pictures.
Another was race, white children probably had more access to magazines and books.
Hudson, culture affecting perception: evaluation
Hudston perpetual set and culture evaluation:
- the instructions and material may not make sense, language barrier, lost in translation.
- some participants may of been confused by the drawing on paper as they hadn’t seen paper before, more familar with cloth and in other studies reacted differently if the picture was presented in this medium.
- Poor design and also conducted in the 1960’s , poor design and no control groups so results could lack validity.
Name a study on emotion affecting perception
Elliott McGinnies
What study did Elliott McGinnies undertake
Perpetual Set and Emotion
McGinnies emotion affecting perceptual set: aim, method, conclusion, result.
McGinnies peceptual set and Emotion:
Aim to see if things that cause anxiety are less likely to be noticed that those that are not.
Method: Students 8 male and 8 female
Shown a series of neutral and mildly offensive words which, once recognised they had to say out loud.
reactions measures using galvanic skin response.
Result: Participants took longer to say the offensive words and the GSR reflected their discomfort.
Conclusion: Emotion is a factor in perceptual set.
Brain momentarily blocks something it finds offensive, embarrasing, causing anxiety. McGinnies called this “Perceptual defence”.
What is Galvanic skin response
a machine that measures the electrical charges on the skin surface.
McGinnies Emotion affecting perceptual set, evaluation.
McGinnie Perceptual set and emotion evaluation:
+ object measured used, GSR, compared to other studies which were self reporting.
- Delayed response could of been more embarrassment of reading out rude words in a study so awkwardness an EV.
- Conradictory results with other studies where there was no delay so cannot explain Why perceptual defence occurs.
Name a study of Perceptual Set and Motivation
JC Gilchrist and Lloyd Nesberg (1952)
What study did JC Gilchrist and L|oyd Nesberg do
Perceptual set and motivation
Gilchrist and Nesburg, Perceptual Set and Motivation: Aim, method, result and conclusion.
Gilchrist and Nesburg Perceptual Set and Motivation:
Aim: To see what effect food deprivation would have on the perception of food related pictures. Would the picture appear brighter?
Method:
26 undergrades
Food deprived for 20 hours
Also a control group not deprived of food.
Participants shown 4 slides (steak, fried chicken, hamburg and spaghetti) for 15 seconds. They were told it was an exercise in matching pictures.
After each slide the projector was turned off and then turned on again with a dimmer setting.
Participants were asked to adjust the brightness so it looked the same as before.
Result:
Food deprived participants adjusted the brightness more than it had been before.
This didn’t happen for the non food related group.
Concusion:
Hunger is a motivating factor that affects perception. Being deprived heightened the sensitivity to the food related pictures making the appear brighter.
Gilchrist and Nesberg, Perceptual set and motivation. Evaluation
Evalutation of Gilchrist and Nesburg study of Perceptual Set and Motivation, evaluation:
+ Support from similar studies ie Sanford (1936) deprived participants for varying times, the longer deprived the more likely they were to perceive pictures as food, ie brown blob a hamburger.
- Ethical, food deprivation.
- Not like every day life. Pictures of food, not real food, also judging pictures for brightness is not something we do in everyday life.
Jerome Bruner and Leigh Minturn (1955)
what study
Perceptual Set and Expectation
Who did a study on Perceptual Set and Expectation
Jerome Bruner and Leigh Minturn (1955)
Bruner and Minturn, study of Perceptual Set and Expecation. Aim, method, result,conclusion
Bruner and Minturn, study of Perceptual set and Expectation:
Aim: To see if participants interpretation of an ambigous figure was affected by the context in which it was shown.
Method:
The ambigous figure used was a cross with the line across readable either as A B C or A 13 B and down 12 13 14 or 12 B 14.
Independents group design.
Participans where either shown the line top to bottom or left to right.
Result:
The group that saw a sequence of letters reported the ambiguous figure as a B and the people shown a list of numbers reported the ambiguous figure as a 13.
When participants where asked to draw the figure they maintained the same result.
Conclusion: Study suggests that expectation is an important influence on perceptual set. Changing the context changes the expectation.
Bruner and Minturn study on Perceptual Set and Expectation. Evalutation.
Bruner and Minturn study on Perceptual Set and Expectation, Evaluation.
- Artificial task. Ambiguous figures are meant to be ambiguous.
- Independent groups design: issue with individual differences between the groups. ie in one group there may of been people who were more predisposed to see the letter B for example if their name began with a B.
+ Real world application. It explains errors that people make in every day life. Sopports Gregory that perception is an active process and we use clues to come up with a hypothesis (a guess about what they are seeing).
What is Trapezoid
a four sided shape with at least two parallell lines.
How does Ames room work
it is a trapezoid and not square.
What is perceptual set
Perceptual set is the tendency for our brain to notice some aspects around you and not others.
