The effect of comparison on the perceived similarity of complex visual stimuli

Engelbrecht, Paula Christiane. 2018. The effect of comparison on the perceived similarity of complex visual stimuli. Doctoral thesis, Goldsmiths, University of London [Thesis]

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Abstract or Description

Comparison has been shown to decrease the perceived similarity of artificial face stimuli that are difficult to discriminate (Mundy, Honey, & Dwyer, 2007). This thesis presents seven experiments that examined the effect of comparison on the perceived similarity of a wider range of unfamiliar face stimuli. Participants were asked to compare two faces before either rating their perceived similarity, or deciding whether they are the same person. In the first five experiments participants were shown face pairs that ranged in phenotypic similarity—the degree to which the two faces look alike. With the exception of highly similar face morphs comparison was found to increase the perceived similarity of both phenotypically similar and dissimilar face pairs, relative to a no-comparison control. This finding suggests that for most naturally occurring face stimuli, comparison results in an increase in perceived similarity. In the last two experiments the quality of one of the stimuli in each pair was degraded to simulate the effects of poor quality video footage. A comparison-related decrease in perceived similarity was found in both experiments. This finding suggests that pictorial differences between face stimuli—including differences in image quality, camera distance and lighting, variations in pose and facial expression, and the presence of disguises such as hats and sunglasses—play an important role in mediating the effect of comparison on perceived similarity.

Item Type:

Thesis (Doctoral)

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Comparison, faces, face processing, face matching, similarity

Departments, Centres and Research Units:



30 November 2018

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Date Deposited:

20 Mar 2019 16:22

Last Modified:

07 Sep 2022 17:14


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