PSY504 Final Term Highlighted Handouts Lectures 19-45

Table of Contents

Lesson 1 The information processing approach Lesson 2 Cognitive Neuropsychology Lesson 3 Cognitive Neuropsychology II Lesson 4 Visual sensory memory experiments I Lesson 5 Visual sensory memory experiments II Lesson 6 Attention Lesson 7 Automaticity Lesson 8 Pattern recognition Lesson 9 Pattern recognition: Feature analysis Lesson 10 Pattern recognition: Gestalt theory of perception Lesson 11 Object perception Lesson 12 Lesson 13 Pattern recognition: Neural networks Lesson 14 Pattern recognition: Effects of sentence context Lesson 15 Memory: STM Lesson 16 Memory: chunking Lesson 17 Memory: The Nature of Forgetting Lesson 18 Memory: Long Term Lesson 19 Memory: Interference Lesson 20 Memory: Recall Vs Recognition Lesson 21 Memory: Forgotten Memories Exist Lesson 22 Memory: Representation of Knowledge Lesson 23 Memory: Representation of Knowledge, Schema Theory Lesson 24 Memory: Representation of Knowledge (Memory for Stories) Lesson 25 Memory: Representation of Knowledge (Application for Studying) Lesson 26 Mental Imagery Lesson 27 Eidetic imagery Lesson 28 Language and thought Lesson 29 Cognitive development Lesson 30 Interference Lesson 31 Interference (continued) Lesson 32 Recall versus recognition Lesson 33 Long term memory (forgotten memories) Lesson 34 Representation of knowledge Lesson 35 Levels of categories Lesson 36 Schema theory Lesson 37 Schema theory (continued) Lesson 38 Psychological reality of scripts Lesson 39 Applications for studying Lesson 40 Study methods Lesson 41 Mental imagery Lesson42 Eidetic imagery Lesson43 Language and thought Lesson44 Cognitive development Lesson45 Cognitive development and revision

Lesson 19

OBJECT PERCEPTION (continued)

Biederman (1987) proposed three stages in recognition of an object as a configuration of simpler components Segmentation into sub-objects Classify the category of each sub-object Recognition as a pattern made of sub-objects

1. Segmentation

Sub-objects are defined by their line contours – Edge and bar detectors from David Marr. Hoffman and Richards (1985) – Gestalt principles can be used to segment an outline representation of an object into sub-objects. They observe that where one segment joins another there is typically a concavity in the line outline.

2. Classification of sub-object categories

Second, once an object has been segmented into basic sub-objects, one can classify the category of each sub-object. Biederman (1987) argues that there are 36 basic categories of sub-objects, which he calls Geons which is abbreviation of geometric ions. The five geons are showed in following figure. There are geons that are making different objects. Like number 1 geon is a part of telephone. And geon number 5 is a receiver of telephone set. He uses geons to explain the objects. He says we can vary the size of the shape and get different objects. Same type of geons makes different things of different organization. Altogether Biederman proposes there are 36 geons that can be generated in this manner and that they serve as an alphabet for composing objects, much as letters or phonemes serve as the alphabet for building up words.

3. Recognition of object

Third, having identified the pieces out of which the object is composed and their configuration, one recognizes the object as the pattern composed from these sub-objects or pieces. Thus, recognizing an object is like recognizing a letter; the sub-objects become the features. Minor details and variations don’t matter. As in the case of letter recognition there are many small variations on the underlying features geons that should not be critical for recognition. Edges are more important than texture to define geons. Color, texture, and small detail should not matter. This predicts that schematic line drawings of complex objects which allow the basic geons to be identified should be recognized as quickly as detailed color photographs of the objects.

Biederman conducted an experiment to test his hypothesis. He showed different shapes to subjects. They created two conditions. Segment deletion Component deletion

In that experiment some objects had whole components deleted while others had all the components present but segments of these components were deleted. They presented these two types of degraded figures to subjects for various brief intervals and asked them to identify the objects. Like in above figures, the components of elephants are separated and showed. In one figure the components were deleted.