object recogniton Flashcards
What is perception?
The ability to extract meaning from sensory input, involving audition, taste, touch, and smell, but predominantly studied in vision.
What percentage of neurons in the cortex are involved in vision?
Over 50%.
What are the two processing streams in vision, and what do they represent?
The ventral stream is the “what” pathway (object recognition), and the dorsal stream is the “where” pathway (spatial location).
What does the study by Tootell et al. (1982) suggest about the visual system?
It supports the idea that a near-perfect representation of the external world is projected onto the primary visual cortex.
How was the study by Tootell et al. conducted?
Monkeys’ eyes were held open, exposed to patterns, and injected with radioactive isotope glucose while unconscious.
What are the three stages of the object recognition model?
- Local features (e.g., edge detection, contrast).
- Shape representation (e.g., Gestalt principles, feature integration).
- Object representation (stored knowledge).
What is the main idea of Gestalt principles?
The whole visual percept is more than the sum of its parts, as the system makes assumptions based on the environment and prior experience.
What are examples of Gestalt laws of perceptual organization?
Good continuation and closure, which can create illusions like illusory contours.
What is a ‘primal sketch’ in shape perception?
A representation of primitives like edges, orientations, and colors created through bottom-up processes (Marr, 1982).
How do top-down processes influence shape perception?
They group primitives into larger structures like lines, curves, and blobs using Gestalt laws.
What are the three models of object recognition?
Template Matching (prototype theory).
Feature Analysis.
Recognition by Components. (Structural Theory)
What is the core idea behind template matching?
Visual input is matched against internal templates or representations stored in memory.
Where is template matching used outside human perception?
Computer-based object recognition programs.
What does feature analysis propose about object recognition?
It begins with lower-level analysis, searching for simple but characteristic features of an object.
What neurological evidence supports feature analysis?
Orientation-selective cells in the visual cortex.
