Pattern recognition = perception Template theory has problems Prototype theory better Distinctive...
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Transcript of Pattern recognition = perception Template theory has problems Prototype theory better Distinctive...
Pattern recognition
• = perception
• Template theory has problems
• Prototype theory better
• Distinctive features theory better
Structural theory
• Based on how your brain arranges features in the object your looking at
• Feature = part of a stimulus you are perceiving
• E.g., face eyes, mouth, nose, eyebrows, etc.
• Further eyes circles, colors, etc.
More on structural theory
• Important thing = how the features relate to each other
• “T” = horizontal line + vertical line
• “L” = horizontal line + vertical line
• So, T and L have exactly same features
• So, important aspect = how the two features fit together
Geon theory
• Stands “geometrical ions”
• All objects made up of elementary particles (geons)
• Geometrical because they are basic shapes in 3 dimensions
tube
More on geons
• We have in memory about 20-30 different geons
• Our mind divides objects into the geons that comprise it
Geon theory is structural
• We identify objects based on the relationships amongst the geons
cup pail
Crux of the geon theory
• Point arranging the two geons (cylinder and the rounded tube) in two different ways gives two completely different objects
• Arrangement that matters (structure)
• Geons can be stretched, pulled, rotated, etc.
Geon theory
• Biederman (1985)
• How do you know what a cup is?
• A cup is composed of two geons—a cylinder and the rounded tube—in a particular arrangement (knowledge in your memory)
• (look at examples on p.31)
What happens with incomplete objects?
• E.g., coffee cup with broken handle
• Biederman (1985): altered pictures of objects to make the objects incomplete or broken
Easy to seecylinder
Harder toSee cylinder
Biederman (1985)
• Presented two types of objects (one broken where geons are still recognizable; other broken where geons not recognizable) (see p. 32)
• Flashed images on screen people say out loud what the object was
• Results: geons visible ~70% accurate• Geons not easily visible < 50%
accuracy
Biederman experiment
• Conclusion: geons must be identifiable for you to perceive an object
Whole Report Procedure
• Viewed an array of objects in a very short period of time (~ 500 ms)
• Asking how many objects can you perceive in that short period of time?
• Write down what you saw (you “report” the “whole” display)
• In lab, average is about 4.5 out of 9
interpretation
• Obviously, whole report is a difficult task
• But, most people experience “seeing” all of the letters, but can’t write them down or report all of them
• Suggests that you CAN perceive or maybe partially perceive all, but can’t write them all down (maybe because you can’t remember them?)