WHAT IS PERCEPTION, AND HOW DOES IT AFFECT US IN OUR DAILY LIVES.

‘If the doors of perception where cleansed, everything would appear to man as it is, infinite’.

William Blake (1757-1827) (The Marriage of Hell, (Plate 14)).

Simplistically, when we perceive something, we do so by processing the raw data presented to our sense organs (i.e. eyes and ears etc.,). We interpretet this data, and decide what our response will be. Roth (1986) divided perception into two major groups ‘Kinaesthetic Modality’ which gives perception of our bodily position, movement, and orientation, and ‘Visual Modality’ which is the information we receive via our senses, i.e. eyes, ears, smell, and taste. The two combined give us control over how we react to events around us.

Because of the continual input of data from every direction, we could not possibly accept all this information. This would overload our capability to act on data that is important to us, or even life threatening. Therefore we introduce a selection process called ‘Perceptual Set’. Allport (1955) defines ‘Set’ as “A readiness to perceive particular features of a stimuli and ignore or neglect others”. This ‘bias’ enables us to select data that is relevant to us at any given moment. We fine tune our perception to a state of readiness. This leaves us fully prepared, so that we can anticipate what is happening, and sort it out as effectively as possible. Our action, or re-action, to our perceptions, can be coloured by many factors, traits or fears, probably as a result of past experience or learned behaviour.

Firstly, we must have the ‘motivation’ (i.e. the will to do it). although Sanford (1936) and Gilchrist & Nesberg (1952) in their ‘Food pictures/visual brightness experiment’ showed that motivation and emotion in food deprived people can lead to erroneous interpretation of perception. (i.e. the light was perceived to be enhanced when pictures of food where shown.) Another factor is ‘emotion’ (which is our ‘gut’ reaction), which is as important. Lazarus & McCleary (1951) demonstrated, that we have a built in personal defence mechanism that protects us from disturbing stimuli, no matter how faintly presented those stimuli where. Postman et al (1948) said “that people took longer to identify sexual or taboo words than neutral ones”. Thus reinforcing the belief that we have a perceptual defence mechanism. Worthington (1969) says that “How we feel emotionally about a topic affects our perception”. He used neutral and taboo words embedded into a flashing light and recorded the effect of taboo words and our perceptual feeling about them. He points out that ‘perceptual defence’ is a real phenomenon. Bitterman & Kniffin (1953) however called this a ‘Response Bias’ whereby the research participants were just unwilling to say the words out aloud, but where more willing to write them down later on.

Cultural differences between people can also affect our perception. Allport (1954). describes a study which showed how prejudice could affect perception. People accurately picked out (from stereoscopic pictures) members of their own race more easily than other races. Afrikaner’s differentiated more sharply between two races they saw, more than any other participants (? Apartheid memories). Other researchers, Mundy-Castle (1966), and Deregowski (1972) also found differences between the interpretation that African children placed on drawings and perception of heights, visual depths etc., compared to European children. Roth (1986) says “That western cultures have only one word for ‘snow’ whereby Eskimos have many, because the nature of their snow determines whether they can move safely over its surface”. Johnson & Laird (1977) point out that “Educated people are capable of ‘fuzzy logic’ which enables them to rationalise other peoples cultures”.

Expectations play a large part in our perception of an object, if it is based on past experience. This was demonstrated by Bruner & Minturn (1955). who’s study ‘Acquisition Strategies’ used an ambiguous number/letter embedded into text. This was misread by participants, because they expected the number/letter to follow in sequence. This research showed how we select what we think is the expected answer, based on previous knowledge/teaching etc., Alampay (1961) used the ‘Rat-Man’ outline whereby those participants who had, had prior exposure to animal pictures frequently saw the picture as a rat rather than a man, because this was what they expected the picture to be. Solley & Murphy (1960) demonstrated through drawings made by children, that their expectation and therefore perception of Santa Claus became larger and more benevolent the closer they came to Xmas, (this was much reduced after Xmas.)

Two eminent perception theorists, Gregory (1977) and Gibson (1966). proposed differing theories to explain the mechanism of perception.

Gregory (1977) says that “A perceived object is a hypothesis, suggested and tested by sensory data”. and he proposed a ‘Top-down’ system of perception, whereby incoming data is interpreted in the light of past experiences. Gregory emphasises the active nature of perception using our higher mechanisms. The incoming data is subject to perceptual constancy’s such as shape, size, colour and brightness of the object. We also make use of ‘Schematic knowledge’ or ‘schema’ which is ‘a mental representation of our knowledge stored into files’. We can draw information from these files to test ‘perceptual hypothesis’, and if possible draw conclusions by interpretation. Gregory drew extensively on visual illusions to support his views on hypothesis testing. The ‘Necker Cube Illusion’ demonstrates how the brain can switch between two viewpoints looking for identifiers. ‘The Ponzo Perspective Illusion’ again allows hypothesis testing, although we know that it is due to inappropriate constancy scaling. Frisby (1986) called this “Inferential Perception” as opposed to direct perception. The ‘Muller-Lyer Illusion’ shows how we pick up cues because of the intersecting angles and lines. Segal (1963) called this a “Carpeted World Hypothesis” whereby our western world is made up of intersecting straight lines. He also pointed out that other cultures i.e. Africans etc. who’s world is more contoured are less likely to be affected by western illusions.

Gibson (1966) proposed a ‘Bottom-Up’ (Direct Perception) whereby the sensory mechanisms take over more than the higher order mechanisms. He says “ that all the information is picked up directly, and is an active process throughout”. Also “that our ability to convert a 2D image into a 3D image allows us to perceive depth”. Furthermore he believes that “‘motion’ is the key, and that perceptual awareness is reduced when we do not move our eyes or head “ (Our perception is easily misled-led when we look at a distorted still photograph). Finally, “that there is little need to draw on past experiences”.

Gibson criticised Gregory, saying that “Gregory’s theories are only relevant for artificial laboratory conditions, that the available studies are limited” and lastly, “that visual illusions are an unfair test of perception”. Eysenck & Keane (1990) says of Gregory’s theory, “That it best explains perception when we are looking at visual illusions”, but that visual illusions are very much an artificial situation, and that Gregory’s illusions are a bit simplistic and limited”.

Marr (1982) & Neisser (1976) say that Gibsons work has been influential in the work of other theorists. However Gibson’s theory does little to explain the mechanisms of visual illusions. Roth & Frisby (1986) say that “Gibson’s theory seems particularly suited to explaining perception in skilled tasks such as pilots landing a plane etc. where precise information must be directly translated into immediate action”. The conclusion of all these criticisms imply, that both researchers contributed, each in their own way to the total knowledge we now have on perception.

The constructivist’s approach to memory draws on past experiences to remember, and these experiences remain stored in our memory. There are three main levels to memory (although many researchers sub-divide these levels). Firstly we have ‘Sensory Memory’ which only holds information for brief periods of time (500ms), and if not attended to, then it will be lost. Secondly we have ‘Short Term Memory’, this holds information that the sensory level has processed and passed on to it. This stage has three sub-levels, encoding, duration, and recall. However even short term memory has a limited life span of about 30 seconds, and unless used, will be lost. Finally we have our ‘Long Term Memory’, who’s contents can last a lifetime.

Bartlett (1932) defines constructive memory as “An imaginative reaction to experience”. He divides it into three levels. Firstly we encode the data into files which he calls ‘Schemata’. (Collins & Loftus (1975) called this a ‘Spreading Activation’, whereby groups of concepts are filed together for easier recall (i.e. birds, feathers, flying etc.)). Secondly he says “That we recover the information in line with our ‘schemata’ which may need shallow or deep processing for retrieval”. Lastly he states “That we impose meaning on what we observe and it’s recall”.

Bartlett goes on to say that “Constructive memory relies on meaningful material and uses techniques of ‘Serial Processing’ to choose items outside peoples experience”, (i.e. we shift from the unfamiliar to the familiar). He illustrated this with his ‘War of the Ghosts’ experiment. Cardwell (1984) says of this experiment, “The participants tended to remember details of the story in a way that fitted their own cultural knowledge and expectation”. Furthermore, “Their common errors included ‘Rationalisation’ (a tendency to change unfamiliar material to a more familiar representation of similar events)”. Cardwell goes on to say “Other errors such as ‘Filtering’ occurred which is a tendency not to remember unfamiliar events, and a ‘Sharpening’, which is an elaboration of details, to fit the ‘War of the Ghost’s’ theme”. Bartlett himself believed, that “The ‘Schemata’ distorted the way the material was reconstructed during retrieval”. However Eysenck (1993) suggests “It is more likely that if ‘schemata’ do have an effect, it is on the way the information is understood at the time of learning”.

Brewer & Treyens (1981) say that “We have a pre-existing ‘Schemata’ for particular scenes”. In their ‘Standard Office’ experiment, they showed how many of us have a standard memory of scenes and events. (i.e. knowing what a standard office looks like and what’s in it etc.).

The trustworthiness of our memories when giving court evidence, has been explored by many researchers, and Loftus (1973) says that “Eye witness testimony in court tends to be unreliable”. Loftus & Palmer (1974) using leading words inserted into a set question where able to alter how witnesses described the speed of an observed car crash by as much as 25%. Accurate recall of an auto crash was also found by Loftus & Zani (1975) to be very suspect, (people where induced into believing that broken headlight glass was present at an accident, when it was not).

Loftus & Evans (1982) showed how emotional arousal affected accurate recall, whereby less detail was observed when emotions where aroused, (Child shot in face during a bank robbery), than when an ordinary bank robbery was observed.

In conclusion, it is apparent how much our perception is influenced by our cultural heritage. Numerous researchers have shown in this essay how perception differs between the ‘Western’ cultures and that of ‘Afro-Asian’ cultures. Visual Illusions to are shown to be cultural sensitive as well. The work of Gregory and Gibson have added much to our knowledge of perceptual mechanisms. Specifically the work of Gibson shows how we react to sudden complicated movements necessary, in order to drive/fly etc. Some authors have shown how fear, anxiety and hunger etc., can produce an erroneous perceptual answer.

Even in the memory studies, Bartlett’s work reinforces the cultural differences in participants answers. Finally Loftus has shown how eye witness testimony can be manipulated by ‘Leading Questions’ which throw doubts on our legal system, unless we are protected from this method of questioning.

However, in this now multi-cultural, and communication literate world, it should be possible to address these problems as future generations are enlightened, and cultural differences are narrowed.

REFERENCES

Cardwell,M. (1994) A-Level Psychology. Longman Group. London. P47.

ibid., Gibson,E (1966) P134.

Eysenck & Keane, (1990) Verbal Remembering. Alan & Unwin Press. London

Frisby,J (1986) Seeing & Illusion. Oxford Press. London. P 185.

Hayes,N (1994) Foundations of Psychology. Routledge Press. London.

ibid., Alampay (1961)

ibid., Allport (1954)

ibid., Allport (1955)

ibid., Bitterman & Kniffin (1953)

ibid., Brewer & Treyus (1981)

ibid., Deregowski (1972)

ibid., Gilchrist & Nesberg (1952)

ibid., Lazarus & McCleary (1951)

ibid., Mundy-Castle (1966)

ibid., Postman et al (1948)

ibid., Sanford (1936)

ibid., Segal (1963)

ibid., Worthington (1969)

Malim,T. (1994). Cognitive Processes.. Macmillan Press. London. P 112.

ibid., Collins & Loftus (1975)

Roth,I. (1986). Perception & Representation. Open Univ. Press. M/Keynes.

pers. comm., Brunner & Minturn (1955)

“ “ Loftus (1973)

“ “ Loftus & Evans (1982)

“ “ Loftus & Palmer (1974)

“ “ Loftus & Zani (1975)

“ “ Solley & Murphy (1960)

BIBLIOGRAPHY

Argyle.M. (1990) Behaviour. Penguin Press. London.

Cardwell,M. (1994) A-Level Psychology. Longmans Press. London.

Gross,R. (1992) Psychology. 2nd. ed. Hodder & Stoughton. London.

Malim,T. (1994) Cognitive Processes. Macmillan. London.

Margolis,H. (1987) Patterns, Thinking & Cognition. Univ. Chicago Press.

Roth. (1986) Perception & Representation. O.U. Press. London.

Oxford Dictionary of Quotations. 1993. Oxford Press Page 61.