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Flashcards in Object Recognition Deck (17):

Theories of object recognition

Template matching
Feature analysis theory
Recognition by components theory
View centred approach


Template matching theory

First explanation
Compare stimulus with a set of templates or patterns in your memory, works for computers but not humans as if a letter is different from the template, it won't work
Only works for isolated letters, numbers and simple objects


Feature analysis theory

Each visual stimulus is composed of a number of characteristics - each characteristic is a distinctive feature
When you look at a letter your visual system notes the presence/absence of various features then compares it with your memory
Problems include: shouldn't only list features, should describe relationship among features, 2 letters may have same features, only explains simple objects and letters


Recognition by components theory

Explains how humans recognise 3D shapes
Objects are represented as an arrangement of simple shapes called geons - combined to form objects
Problems - requires modifications as people recognise objects less quickly when objects are seen from a weird view


View centred approach

Store a small number of views of 3D objects, rather than just one view
If we see it from an unusual view we will have to rotate it till it matches a view stored
Can make errors


Organisation in the visual perception

Visual system imposes organisation on the complicated world


Gestalt principles

Believes human organise what they see e.g. Patterns not just random objects
Organisation means some things stand out, some go in the background



Ability to extract meaning from sensory input
Made up of previous knowledge about what to expect


Visual System

Our brain receives sensory info allowing us to perceive an object
Visual info goes through occipital lobe


Distal stimulus

Object in the environment


Proximal stimulus

Info registered on sensory receptors
Can recognise objects presented for 1/10 of a second


Illusionary contours

Can see edges even if they aren't present, we fill in blanks which leads to perceptual error


Limitations of visual system

Blind spot in each eye, gaps get filled in, visual system filters things out


Bottom up processing

Characteristics of the shape


Top down processing

Expectations of where the shape is
E.g. Expect to find a shape in certain places
This process is strong when stimuli is ambiguous



Word superiority effect - can identify a single letter more accurately and quickly when in a meaningful word than when it's alone/in a non word
Context speeds word reading up


Errors in object recognition

Change blindness - inability to detect changes in an object or scene
Inattentional blindness - paying attention to some events so missing an unexpected event