Broadly outline some models of object recognition and consider the evidence from case studies for stored knowledge of structural descriptions as in the Humphreys and Bruce (1989) model of object recognition.

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Broadly outline some models of object recognition and consider the evidence from case studies for stored knowledge of structural descriptions as in the Humphreys and Bruce (1989) model of object recognition.

While it is relatively easy to explain how we see, that is, how our eyes work, it is much more difficult to explain how we interpret what we see and recognise objects for what they are.  This essay will initially briefly identify some of the main challenges in designing a model of object recognition.  A number of models have emanated from cognitive psychology to try to address these challenges and explain the processes involved in object recognition.  By outlining two of these models – those of Biederman (1987) and Humphreys et al (1995) – a better understanding of how objects are recognised can be arrived at.  It is also necessary to consider how evidence from case studies has contributed to supporting the basic components of these two models.  Finally, as the two models to be described do not compete with each other, a point will be made proposing an integration of the two to provide a more complete description of the structure and processes of the object recognition system.

There are at least three issues that models of object recognition seek to address.  The first of these is how the cognitive system recognises a three-dimensional figure from a two-dimensional retinal image.  Secondly, and related, is the question of whether the object recognition process is viewer-centred or object-centred.  That is, is it just as easy to recognise an object no matter what position it is in (if this was the case, an object-centred model would be appropriate)?  Or does ease and speed of recognition depend on where the object is in relation to the viewer (in this case a viewer-centred model would be more accurate)?  Thirdly, do we have a stored knowledge of structural descriptions?  The following two models focus on these issues to differing degrees.  As shall be seen later, these challenges are not merely academic: they are also challenges for patients with brain damage resulting in impaired object recognition capabilities.

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Biederman (1987, 1990 in Eysenck & Keane, 2000) proposed a model of object recognition in response to a computational model published by Marr & Nishihara in 1978.  Their model addressed both the ‘2D to 3D’ problem and the ‘object/viewer-centred’ issue by suggesting that we see objects as various combinations of cylinders.  Biederman’s theory made use instead of a total of thirty-six different-shaped basic components which he called ‘geons’.  He proposed initial stages of identifying basic edges and what he called ‘non-accidental properties’ or essentially identifying shapes using Gestalt principles.  Once components were identified they would be matched to object ...

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