Perception

Sensation= the physical process of collecting data from the environment via the senses. The sensations for visual perception are light waves picked up by the eyes, these are sorted by the retina and sent across the brain to the visual cortex.

Perception= The cognitive process of interpreting data once it has been sensed. The brain (visual cortex) takes senses from the eyes and turns these into meaningful images

Illusion= The effect of misinterpreting data – visual illusions are where are brain plays a trick on us and misinterprets the sense data from the eyes.

• Geometric Illusions- one line gets distorted and we get it wrong in our minds, e.g. in the ponzo illusion the top line seems to be further away and wider
• Ambiguous figures- a picture can be seen in more than one way, e.g. Necker cube, , the x sometimes seems to be at the front and back
• Fictions= seeing something which is not there, e.g Kaniza triangle, there is no white triangle in the middle but it seems to be there

Constancies- visual constancies, allow us to see things as remaining the same even though their physical characteristics are constantly changing

• Shape constancy= the ability to perceive the shape of an object as constant, even if it appears to change through movement e.g. moving door
• Colour constancy= the ability to perceive the colour of an object as constant even it apperas to change with changes in lighting e.g. white tshirt in a shadow

Depth perception= refers to the ability of our eyes and brain to add a third dimension ( depth) to everything we see. The brain uses depth cues to help us see in 3d

• Linear perspective- straight lines seem to come together or converge  at a distant point, linear perspective allows us to interpret distance of a road/straight line.
• Height in a plane- if an object is higher to the eyes is seems further away
• Relative size- an object that is bigger seems closer and objects which are smaller seem further away.
• Superimposition- if one object blocks another it seems closer
• Texture gradient– texture is more detailed closer up

Constructivist Theory= perception is constructed using past experiences e.g. we recognise people in our class because we expect to see them

Supports the idea of top down processing – this is when perception is dominated by what we expect to see, the brain uses past experience, cultural features, motivation, expectations and memory to interpret what we see.

An idea linked to this theory is perceptual set- a tendency to perceive something in line with what you expect based on past experiences. 

• Expectations= what you expect to see, e.g. you recognise your friend at your lunch table because you expect to them there
• Motivation= how we are feeling can affect what we see, e.g. if we are hungry we might see pictures of food as brighter than other images ( link adverts)

Perception can’t just be based on individual past experience, as many people perceive the world in a similar way

A new born baby can perceive the world without past experience, e.g babies can recognise faces and complex patterns ( wont walk over a visual cliff)

Perception can not just be about past experience as well fall for the same visual illusions a second time round

It ignores the influence of our natural ability to perceive the world – nativist theory (instinct)

Alternative= Nativist Theory= the theory that perception is a natural and instinctive process. It argues that perception is a bottom up process.

Bottom up processing is when perception is dominated by what enters through the eyes (not what we expect to see)

This theory argues perception is immediate or direct and data driven

Participants= 9 male college students, USA, tested good eyesight

Procedure= Field experience- students taken to a field divided into 4 sections

Used a repeated measure design= groups 3 taken to one section and asked to record guesses of distances of objects, repeated for all sections

Results= Participants estimates of distances were most accurate for real world objects of standard size, therefore this suggest the participants were relying on past experience to guess distance, supporting the constructivist theory

Generalisability - Sample is not very representative as small only 9 plus all male. College students means it is not generalised to rest of population

Reliability - Well-controlled, all participants eyes where tested. The same objects were used

Application: Supports constructivist theory of perception, we use our past experiences to perceive distances.Could be used in eye witness testimonies/advertising

Validity: Task setting was unfamiliar, city dwellers may be not used to field setting and could have distorted findings. Also perception is subjective, use of common objects assumes perceive familiar objects in same way.

Ethics: very little ethical problems – only a small potential of some embarrassment if they got it wrong. Otherwise consent was gathered, debriefing took place and there was no harm or deception to participants.

Advertising and the media use the knowledge of how people view things to maximise the message they want to get across. The application is an attempt to manipulate people’s perception.

If newspaper readers/TV watchers are going to buy a product they need to perceive  they want it. Advertisers can influence perception through presentation

Use of context- advertisers can influence perception by influencing the context it is presented in e.g. putting a burger on a small plate makes it look more appealing