Perception - Unit 2 Flashcards
Sensation
Physical stimulation of the sensory receptors is processed by sense receptors which or brain interprets to lead to perception.
Perception
The organisation and interpretation of sensory information.
What is the difference between sensation and perception?
Sensation is the detection of a stimulus in the environment whereas perception is the brain interpreting and understanding these sensations.
Visual cues
Features of the environment that give us information about movement, distance etc.
Visual constancies
Seeing objects is the same despite seeing them from different angles and distances.
Give two examples of binocular depth cues
Retinal disparity
Convergence
What is retinal disparity
- each eye sees things differently as they are positioned about 6cm apart on the face.
- retinal disparity is the difference between the left and right eye’s view which the brain receives to give information about depth and distance
What is convergence
- Our eyes converge/become closer together when objects get closer to us.
- Muscles around our eyes work harder when objects are close and this information is sent to the brain to give information in depth and distance
Give four examples of monocular depth cues
- Height in plane
- Relative size
- Occlusion
- Linear perspective
What is height in plane
Objects that are higher up in the visual field appear to be further away
What is relative size
Small objects in the visual field appear further away
What is occlusion
Objects that are in front of others appear closer to us whilst objects behind other objects seem further away
What is linear perspective?
When parallel lines converge in the distance, the point at which they come together is perceived to be further away.
What are the 4 main explanations fo visual illusions
Size constancy
Misinterpreted depth cues
Ambiguous figures
Fiction
Describe size constancy as an explanation for visual illusions.
The brain perceives familiar objects as a constant size despite the size of the image they produce on our retina changing with distance
Describe misinterpreted depth cues as an explanation for visual illusions
Objects in the distance that appear smaller are scaled up by our brain so that they look normal size.
Sometimes the brain perceives distance where there isn’t any which creates a visual illusion.
Describe ambiguous figures as an explanation for visual illusions
A type of visual illusion where there are two possible interpretations of the same image and the brain cannot decide which one to choose.
Describe fiction as an explanation for visual illusions
A type of visual illusion that causes the brain to perceive something that is not there.
Give 6 examples of visual illusions
Ponzo illusion Müller-Lyer illusion Necker cube Kanizsa triangle Ames room Rubin’s vase
Explain Ponzo’s Illusion
MISINTERPRETED DEPTH CUES
Converging lines create the illusion of distance, the brain uses size constancy and mentally scales up the more distant line and scales down the closer line
Explain Müller-Lyer illusion
MISINTERPRETED DEPTH CUES
I going fins are shaped like the outside of a building and outgoing fins are shaped like the corner of a room stretching away from us.
This gives the illusion of distance and so we mentally scale up the line that appears closer (outgoing fins) so it appears longer.
Explain necker cube
AMBIGUOUS FIGURES
The same image of the cube can be perceived as pointing upwards to the right or downwards to the left
Explain Kanizsa triangle
FICTION
Illusory contours create the impression that a second triangle is overlapping the first one
Explain Ames room
MISINTERPRETED DEPTH CUE
Explain Rubin’s vase
AMBIGUOUS FIGURE
The image can be perceived as a vase or two faces staring at each other.
Describe Gregory’s constructivist theory of perception and the 4 main parts
proposes that we use past experience to make sense of the world around us
Perception is a construction - the brain uses incoming information from her eyes as well as use the information that we already know about the world.
Inference - the brain uses sensory information that is available and then fills in the gaps, past experience allows us to infer what should be there
Visual cues - when making inferences, features of the environment gives the brain information about depth, distance etc.
Past experience - perception depends on experience which is learned, the more we interact with the world, the more sophisticated out perception becomes.
Give 3 evaluation points of Gregory’s constructivist theory of perception
STRENGTH - supported by research in other cultures
WEAKNESS - explains visual illusions but may not tell us much about the wider world
WEAKNESS - doesn’t explain how perception becomes
Describe Gibson’s direct theory of perception and the 4 main parts
Suggests that the environment gives us all the information we need for perception
Direct perception - sensation and perception are the same thing, we don’t need past experience to interpret what we see
Optic flow patterns – when moving, the point at which we are moving towards remains stationary and everything else moves away from it, this is detected by our eyes and tells our brain that we are moving so we know our speed and direction of travel
Motion parallax - a monocular depth cue which tells the brain the speed at which we are moving - objects closer in our visual field appear to move faster than objects further away
Influence or nature - our ability to perceive is innate
Give 3 evaluation points of Gibson’s direct theory of perception
STRENGTH - the theory has real world meaning
STRENGTH - Scientific evidence from studies of babies
WEAKNESS - struggles to explain visual illusions
What are the 4 factors that can affect perception
Expectation
Motivation
Culture
Emotion
Perceptual set
The tendency of our brain to notice certain aspects of the sensory environment more than others
Culture
The social world that works around you
Who investigated thee effect of culture on perceptual set
Hudson
Aim of Hudsons study
To find out whether people from different cultural/educational backgrounds perceived depth cues in 2D images differently
Method of Hudson’s study
- showed 2D drawings to South African participants ( native black people who were either schooled or unschooled and white people of European descent who were either schooled or unschooled)
- participants had to say which animal the man was trying to spear
- the spear pointed to an elephant and an antelope by depth cues suggested that he was really pointing at the antelope
Results of Hudson’s study
Despite the picture using height in the visual field and relative size, many believed the spear to be pointing towards the elephant
Schooled participants were more likely to perceive depth than unschooled participants
White schooled participants were more likely to perceive depth than the black schooled participants
Conclusion of Hudson’s study
People from different cultural/educational backgrounds use depth cues differently and have a different perceptual set.
This supports Gregory’s theory as it shows that depth cues are learned.
Who investigated the effect of emotion on receptacle set
McGinnies
Aim of McGinnies’ study
McGinnies wanted to see whether things that cause anxiety are less likely to be noticed than things that are emotionally neutral.
Method of McGinnies’ study
Eight male and eight female students were shown neutral and offensive ‘taboo’ words flashed on a screen.
After each word was shown participants had to say it out loud.
The amount of emotional arousal was measured through their galvanic skin response (GSR) which records electrical changes in the skin.
Results of McGinnies’ study
Participants took longer to say offensive words like ‘bitch’ and ‘penis’ than neutral ones like ‘apple’ and ‘dance’.
Taboo words produced bigger changes in the GSR than neutral words.
Conclusion of McGinnies study
This shows that emotion affects perceptual set.
Perceptual defence is used by the brain when confronted with words that are offensive or cause anxiety.
Give 3 brief evaluation points for Hudson’s study
WEAKNESS - instructions may not make sense.
The language barrier means translations of the method may have been unclear.
This will therefore affect the validity of the results.
WEAKNESS - some of the participants may have been confused by seeing drawings on paper.
When more familiar materials such as cloth were used they gave different answers.
This shows representation affects results.
Extra: Poor design
WEAKNESS - the research is from a long time ago and may be poorly designed.
Early cross-cultural studies of perception often did not include things like proper control groups.
This caused the results of cross-cultural differences in perception to lack validity.
Give 3 brief evaluation points for McGinnies study
STRENGTH - used an objective measurement of emotion.
A scientific method was used – the galvanic skin response – to test biological anxiety responses.
This produces results that are less open to bias than, for example, rating scales.
WEAKNESS - delayed recognition may be more to do with embarrassment.
Participants may have hesitated in giving their response as they were uncomfortable repeating rude words in a study.
This suggests that awkwardness may have been an extraneous variable.
WEAKNESS -the results are contradictory.
This is because sometimes they suggest we are more likely to notice emotional material, and sometimes we are less likely.
This makes it difficult for psychologists to draw firm conclusions.
Who investigated the effect of motivation on perceptual set?
Gilchrist and Neuburg
Aim of Gilchrist and Neuburgs study
Gilchrist and Nesberg aimed to find out if food deprivation affects the perception of pictures of food.
Method of Gilchrist and Nesburg’s study
Two groups of students: one group deprived of food for 20 hours and a control group (not hungry).
Students were shown four slides, each one showing a meal.
The slide was displayed for 15 seconds.
The picture was shown again, but dimmer, and participants had to adjust the lighting to make it look the same as it did before.
Results of Gilchrist and Nesburg’s study
Participants perceived the food as brighter the longer they were deprived of food.
The control group (who were not deprived of food) didn’t perceive the food as brighter.
Conclusion of Gilchrist and Nesburg’s study
Being deprived of food increased perceptual sensitivity.
This shows that hunger is a motivating factor that affects the way food-related pictures are perceived.
3 brief evaluation points of Gilchrist and Nesburg’s study
STRENGTH - similar studies have found similar results
WEAKNESS - studies in this area are unethical
WEAKNESS - not like everyday live
Who investigated the effect of expectation on perceptual set
Bruner and Minturn
Aim of Bruner and Mintern’s study
Bruner and Minturn aimed to find out whether an ambiguous figure was seen differently if the context of the figure was changed.
Method of Bruner and Minturn’s study
An independent groups design was used where participants were either presented with a sequence of letters or a sequence of numbers with the same ambiguous figure in the middle.
The ambiguous figure could be seen as either the letter B or as the number 13.
Participants had to report and also draw what they saw.
Results of Bruner and Minturns study
Those who saw a sequence of letters were more likely to report the figure as being the letter B and tended to draw a ‘B’.
If shown numbers they were more likely to say it was the number 13 and drew a ‘13’.
Conclusion of Bruner and Minturn’s study
This shows that expectation of what the figure represented was affected by the context that the figure was presented in.
3 brief evaluation points of Bruner and Minturn’s study
STRENGTH - the study has real life application
WEAKNESS - used an artificial task
WEAKNESS - there were individual differences between groups
