How do we generate mental representations of 3D objects?
There are two theories
- Marr’s model
- Biedermans theory
Marr’s Model
Three stages wher visual information is represented in different ways
1. Primal sketch - 2D description, viewpoin dependent and basic features
2. 2,5D sketch - Depth cues added, still viewpoint dependent
3. 3D representation
Not sure how stage 2 to 3 happens
Biederman’s recognition-by-components Theory
- Made out of besic shapes
Geons - Recognition involves recognizing geons and their configuration
Breaking them down
Mug, telephone, flashlight etc
RBC - Identifying geons
- Edge detection
Different combinations allow us to identify geons, even when things are partily covered (if we see the impoartna shapes) - View-point independent
RBC - Shortcomings
- Its incomplete, tied to a bottom-up processing
Object recognition is influenced by context - We see objects as a “whole”, not components
- Several processes cooperate to create a 3D representation
What are some top-down influences on object recognition?
- Conceptual priming effects with ambigious figures
What are we more used to seeing?
Differences between similar objects - What you see first is often influenced from previous information
- Context can help reognizing and detecting objects in the real world, where we cant rely purely on local features (blurry picture)
Location, size, pose and semantics
Apperceptive agnosia
Disurption in perceiving patterns
- Cant discriminate objects from each other
The role of context in object recognition - Intro
- Objects never occur in isolations
- Surprising ability to recognize thousands of objects
- Visual search
Problem solving with help of context
Contextual influences on object recognition - Article
- Efficiency of search and recognition
Familiar settings - easier to find some objects - Real-world configurations governed by “rules”
Finding common patterns - 100s of pictures - Important when local features are insufficient
Blurry pictures - The object relationship to other objects and the context its in
Multiple levels of context - Article
Semantic - what makes sense
Spatial configuration - expectations on where objects should be at
Pose
First two are good for quick recognitions
Implicit learning of contextual cues - Article
Contextual cueing
- Learning certain contingencies by observing
- Certain relationships between objects
Affects on attention
- Biases
Prior knowledge / memory
Context help with simplifying object discriminations
Cognitive Research and Context - Article
- Statistical summaries
Effective source of contextual inference
Elements that do or don’t correspond with each other - Scene representations
Global scene
Holistic view, adds more understanding - Fixing eye movements
Direct attention where it makes sense
