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?)