Factors Affecting Perception


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Expectation and Past Experience

Bruner and Postman(1949) showed playing cards with Black Hearts and red spades at very fast speeds on a tachistoscope and found that these unusual cards would be seen as normal cards at first but at slower speeds ‘compromise’ perceptions emerged, e.g. brown or purple hearts were seen.


Tulving and Gold (1963) showed participants sentences with 4,6 or 7 words missing. The fewer the words missing, the quicker they would correctly guess the target word.


Reward and Punishment

Rewards are a way of increasing a person’s motivation. Punishment decreases it. For example, Schafer and Murphy(1974) gave participants a reward everytime they named a particular face, one facing left or one facing right. They were punished losing 2 or 4 cents when they did not name the correct face.

Later, when the participants were shown an ambiguous image made up from both faces the participants ‘saw’ the only one they had been rewarded for.




Research question – Are perceptions affected by emotionally threatening stimuli such that you are not even aware of them


8 male and 8 female participants


Participants were shown a list of words , 11 were neutral and 7 critical (emotionally-toned) words. Exposure time was gradually increased from 0.01 seconds until the word was correctly identified (tachistoscope was used)

Stimulus words (critical words shown in italics)

Apple                  river                   penis

dance                  whore               music

sex                      sleep                   trade

child                    anus                   filth

belly                    broom                clear

glass                    stove                   bitch


P’s were asked to report whatever they saw or thought they saw. At the same time a physiological measure of emotionality was taken using the Galvanic Skin Response (GSR) similar to a lie detector. It measures the amount of moisture(sweat) on the skin, emotional states are associated with arousal or sweating.


Results showed that on both measures, participants showed that emotion is related to critical words

1)When  shown  critical words participants had higher mean GSR’s. This happened before the words were recognised

2)Participants required significantly longer exposure times to report the critical words correctly


In interpreting this the fact that the participants had an emotional response but didn’t simultaneously recognise the words , shows that the selection of visual data takes place early on and not necessarily with conscious knowledge. In this case perceptual set acts as a defence.

The Muller Lyer Illusion

The line with the ingoing fins looks like the corner of a building, and this makes the vertical line seem closer. The out going lines are like the corner of a room and therefore the vertical line seems to be receding and as a result is perceived as longer


A logical judgement made on the basis of a sample of evidence, previously made judgements prior conclusions etc. rather than on direct observation – it is also the cognitive process by which such a judgement is made

Hudson (1960)


Hudson used pictures of hunting scenes. Participants in Africa (from various tribes) were shown a picture at a time  and asked to name all the objects in the picture in order to determine whether or not elements were correctly measured. I.E what is the man doing ? Which is closest to the man. If the participants recognised the correct depth cues they were classified as having 3-D perception if they didn’t recognise the depth cues 2-D

Both children and adults from differing backgrounds had difficulty. Perhaps these people had not had much experience of looking at pictures before which was causing the poor results


The study of relationship between organisms and their environments