The Effect of Expectation on Perception (AQA GCSE Psychology): Revision Note

Expectation & perception

• Expectation is a belief about what is likely to happen, based on past experience

• Expectation is one of the factors that creates a perceptual set – a readiness to perceive some things rather than others

  • When we expect something, we are more likely to notice it, attend to it, and interpret ambiguous information as it

• We therefore tend to 'see what we expect to see', e.g. waiting for a friend at the ice rink you keep mistaking strangers with a similar height, hair or coat for her, because you are primed to see her

• Ambiguous figures, such as the 'rat-man' are useful for studying expectation because the image itself doesn't settle which interpretation we perceive – so expectation does

Bugelski & Alampay’s (1961) ‘rat-man’ ambiguous figure: can you see both a man wearing glasses and a rat in this image?

• Bugelski & Alampay (1961): participants were shown a sequence of pictures before the rat-man

• Those who had seen pictures of animals mostly saw a rat; those who had seen pictures of faces mostly saw a man

• The same image was perceived differently depending on what participants had been led to expect

Bruner & Minturn (1955)

• The researchers’ aim was to see if expectation was an important factor in perceptual set

• The participants were presented with an ambiguous figure comprising an image which could be interpreted as the number 13 or the letter ‘B’ (see below):

• Participants in one condition were shown a series of numbers descending the page vertically, with the ambiguous figure at the centre of the list

• Participants in the other condition were shown a series of letters going across the page horizontally with the ambiguous figure at the centre:

• The participants were asked to say what they saw

  • Participants in the vertical ‘numbers’ condition were more likely to say that the ambiguous figure was the number 13

  • Participants in the horizontal ‘letters’ condition were more likely to say that the ambiguous figure was the letter ‘B’ (this was also true when participants were asked to draw the ambiguous figure)

• The researchers concluded that expectation influences perceptual set: what participants had just seen created a readiness to perceive the ambiguous figure in a particular way

• This shows that the same visual information can be perceived differently depending on what the person has been led to expect

  • This is evidence that perception is not based on the stimulus alone but on past experience, supporting Gregory's constructivist theory

Evaluation of the effect of expectation on perception

Strengths

• There is good application to this theory:

  • understanding how expectation can influence perception could be used to avoid errors in, for example, policing e.g. just because someone is running down the street in a high-crime area does not mean that they have been up to no good (they could just be running for a bus!)

• The study used a standardised procedure which means that it could be replicated to test the reliability of the findings

Weaknesses

• It is difficult to test the effect of expectation on perception within real-world settings as it tends to happen unpredictably, without warning and often without people knowing that it is happening thus lab experiments are used to test it which lack validity

• Participant variables may have interfered with the study’s results e.g. the ‘numbers’ condition may have included more participants who were Maths-oriented which would mean that they were already predisposed to seeing numbers rather than letters i.e. this would constitute a form of bias which would further invalidate the findings