The Effect of Expectation on Perception (AQA GCSE Psychology)

• Expectation involves an individual responding to stimuli on the basis of them having built up a sense of what they are about to see/hear/smell/touch/taste
• Expectation affects perception as it sets out an initial idea as to what is going to be experienced in a given situation or when presented with specific stimuli e.g. you are expecting to meet your friend at the ice rink and you keep ‘seeing’ her mistakenly (you keep thinking people who have the same hairstyle, are the same height, wear similar clothing are your friend because you are expecting to see her at the rink)
• An example of a visual illusion which plays upon expectation is the ambiguous figure: an image that can be perceived or interpreted in more ways than one e.g. Rubin’s vase; the ‘rat-man’ figure 

Rat-Man Visual illusion Diagram

Bugelski & Alampay’s (1962) ‘rat-man’ ambiguous figure: can you see both a man wearing glasses and a rat in this image?

• The ‘rat-man’ figure can be used in research on expectation and perception:
  • If participants are shown a series of images of faces first they tend to see the ‘man’ part of the ‘rat-man’ figure (and vice versa if they are shown a series of animals first), hence they see what they expect to see

• The researchers’ aim was to demonstrate how the immediate physical context presented alongside an ambiguous figure could influence the perception of that figure
• 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):

Bruner & Minturn Diagram

• 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 perceptual set is influenced by the context in which a stimulus is presented
  • It is possible to predispose people to interpret visual information differently, depending on the context provided

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