Perceptual processes ch 4
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Questions and Answers

Which of the following is NOT a principle of Gestalt psychology?

  • Similarity
  • Occlusion (correct)
  • Closure
  • Proximity

    • What is the primary concept behind the Gestalt principle of 'Continuity'?

  • Elements arranged in a line or curve are perceived as related. (correct)
  • The brain completes missing parts of an image to make a whole.
  • Objects that move in the same direction are perceived as a group.
  • Objects that are close together are perceived as more related than those that are far apart.

    • How does the Gestalt principle of 'Continuity' relate to 'Texture Segmentation'?

  • Texture Segmentation uses Continuity to find edges or boundaries between different textures. (correct)
  • Continuity is a way to segment textures by identifying elements with different orientations.
  • Continuity is a tool for grouping textures with similar patterns together.
  • Texture Segmentation is a method for applying different textures to individual elements based on their position.

    • Which statement best describes the role of 'Closure' in Gestalt psychology?

    <p>It explains how the brain completes incomplete shapes to make a whole. (B)</p> Signup and view all the answers

    Why is the Gestalt principle of 'Continuity' considered to be a 'grouping rule'?

    <p>It shows how our brains connect elements that lie on a continuous line or curve, making them appear as a single entity. (C)</p> Signup and view all the answers

    What was the primary objective of the PANDEMONIUM model?

    <p>To understand how simple letters are recognized by humans. (D)</p> Signup and view all the answers

    What is the primary limitation of using templates for object recognition?

    <p>Templates are inflexible and cannot adapt to variations in object appearance. (B)</p> Signup and view all the answers

    What is a major difference between templates and structures in object recognition?

    <p>Structures rely on specific feature configurations, while templates utilize a more general approach. (D)</p> Signup and view all the answers

    Which of the following statements accurately describes the use of geons in object recognition?

    <p>Geons are geometric icons used to construct perceptual objects. (C)</p> Signup and view all the answers

    Which of the following is a drawback of using geons for object recognition?

    <p>Geons are not viewpoint independent, meaning their recognition can be affected by the observer's perspective. (C)</p> Signup and view all the answers

    What is the primary purpose of the 'Demons' in the PANDEMONIUM model?

    <p>To represent different stages of cognitive processing involved in object recognition. (B)</p> Signup and view all the answers

    What is the main issue encountered when using templates to represent objects?

    <p>Templates cannot be easily modified to accommodate new or unusual examples. (C)</p> Signup and view all the answers

    What is the primary advantage of using structures over templates in object recognition?

    <p>Structures are able to handle variations in object appearance better than templates. (C)</p> Signup and view all the answers

    Which of these is an example of a superordinate-level category?

    <p>Vehicle (C)</p> Signup and view all the answers

    What type of processing does the text suggest is used for face recognition?

    <p>Holistic processing (B)</p> Signup and view all the answers

    What is the primary function of the dorsal pathway?

    <p>Extracts information about the location and shape of objects (A)</p> Signup and view all the answers

    Which area of the brain is primarily associated with identifying the identity of objects?

    <p>Inferotemporal cortex (C)</p> Signup and view all the answers

    Why is face recognition considered special?

    <p>It requires a unique combination of feature and holistic processing. (B)</p> Signup and view all the answers

    What type of stimuli do neurons in the inferotemporal cortex respond well to?

    <p>Hands, faces, or specific objects (A)</p> Signup and view all the answers

    What does the text suggest about the processing of faces in different contexts?

    <p>The text highlights the variability and flexibility of face recognition depending on context. (D)</p> Signup and view all the answers

    What is one benefit mentioned in the text of having multiple recognition committees for object processing?

    <p>It allows for faster identification by comparing objects across and within different categories. (B)</p> Signup and view all the answers

    What is a significant characteristic of the receptive fields of neurons in the inferotemporal cortex?

    <p>They are very large and cover substantial areas of the visual field. (D)</p> Signup and view all the answers

    What do boundary ownership cells primarily contribute to in visual processing?

    <p>Understanding spatial relationships in the environment (B)</p> Signup and view all the answers

    The concept of the 'grandmother cell' suggests that:

    <p>Individual cells may respond selectively to very specific stimuli. (C)</p> Signup and view all the answers

    What evidence did Quiroga et al. (2005) provide regarding object recognition in humans?

    <p>Cells respond selectively to specific stimuli in homologous regions. (C)</p> Signup and view all the answers

    Which area of the brain processes the 'how to use/interact with the object' information?

    <p>Dorsal pathway (A)</p> Signup and view all the answers

    Why are our assumptions about the world generally good?

    <p>They help us to understand and interpret information more effectively. (A)</p> Signup and view all the answers

    What is the primary goal of figure-ground assignment?

    <p>To determine which regions of an image belong to the foreground or background. (D)</p> Signup and view all the answers

    Which of the following is NOT a principle of figure-ground assignment?

    <p>Color (B)</p> Signup and view all the answers

    What is the law of common fate?

    <p>Objects that move in the same direction at the same time are likely to be part of the same object. (C)</p> Signup and view all the answers

    What is the role of closure in visual perception?

    <p>To fill in missing information to create a complete image. (C)</p> Signup and view all the answers

    Which of the following is NOT a nonaccidental feature?

    <p>Curved line (C)</p> Signup and view all the answers

    What is T junction?

    <p>A feature that indicates occlusion (D)</p> Signup and view all the answers

    What is relatability?

    <p>The degree to which two line segments appear to be part of the same contour. (B)</p> Signup and view all the answers

    What is the main concept of structuralism?

    <p>Complex objects can be understood by analyzing their individual components. (A)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of mid-level vision?

    <p>Involves the extraction of basic features like color, shape, and orientation. (A)</p> Signup and view all the answers

    According to the content, what is a key difference between human and computer-based edge detection?

    <p>Humans can detect edges in low-contrast environments, while computers require high contrast. (C)</p> Signup and view all the answers

    What phenomenon demonstrates the limitations of structuralism in explaining perception?

    <p>The ability of humans to detect edges even when they are not physically present. (A)</p> Signup and view all the answers

    What is the main point of Gaetano Kanizsa's Kanizsa figures?

    <p>To show that we can perceive continuous lines even when they are incomplete. (D)</p> Signup and view all the answers

    How does the concept of illusory contours challenge the notion of structuralism?

    <p>It shows that the whole is not simply the sum of its parts, but rather a result of active interpretation by the brain. (A)</p> Signup and view all the answers

    Why is it important to understand the limitations of structuralism in visual perception?

    <p>It helps us appreciate the complexity of the human brain and its role in constructing reality. (D)</p> Signup and view all the answers

    Which of the following is an example of how we can infer edge information even when it is missing?

    <p>All of the above. (D)</p> Signup and view all the answers

    Flashcards

    Retinal Ganglion Cells

    Neurons that detect spots of light in the visual field.

    Primary Visual Cortex

    Brain area that detects bars and edges in the visual input.

    Extratiate Cortex

    Region bordering primary visual cortex, involved in complex visual processing.

    Dorsal Pathway

    Pathway from occipital to parietal lobe for 'where' and action in visual processing.

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    Ventral Pathway

    Pathway from occipital to temporal lobe for object identity in vision.

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    Inferotemporal Cortex

    Brain region important for recognizing objects and faces.

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    Grandmother Cell

    Hypothetical neuron that responds to a specific, familiar stimulus.

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    Boundary Ownership Cells

    Cells that determine which side of a boundary an object belongs to.

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    Gestalt Psychology

    A psychological theory stating that the whole is greater than the sum of its parts.

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    Proximity

    Objects that are close together are perceived as related.

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    Continuity

    Elements arranged on a line or curve are perceived as connected.

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    Closure

    The brain fills in missing parts to create a whole image.

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    Texture Segmentation

    Carving an image into regions based on texture properties.

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    Structuralism

    A school of thought analyzing complex objects through their components.

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    Wilhelm Wundt

    A founder of Structuralism known for studying consciousness.

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    Edward Bradford Titchener

    Pioneered the concept of Structuralism in psychology.

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    Mid-level vision

    Stage of visual processing after basic features and before object recognition.

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    Finding edges

    Perception of edges that defines the boundaries of objects in vision.

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    Illusory contours

    Perceived contours that exist without actual changes in the image.

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    Kanizsa figures

    Optical illusions demonstrating how the human brain perceives edges.

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    Problem with Structuralism

    A critique stating wholes can't be made from parts that don't exist.

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    Implicit Knowledge

    Understanding about the world used to make assumptions.

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    Assumptions

    Beliefs that help interpret ambiguous information

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    Figure-Ground Assignment

    Determining foreground (figure) vs background (ground) in an image.

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    Surroundedness Principle

    Surrounding areas are likely perceived as the background.

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    Size Principle

    Smaller regions in a visual field are often seen as figures.

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    Law of Common Fate

    Regions moving in sync are perceived as a single object.

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    Relatability

    The perceived connection between two line segments as part of the same contour.

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    Nonaccidental Features

    Traits that indicate object identity, independent of viewpoint.

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    Entry-level category

    The quickest label that comes to mind for an object.

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    Subordinate-level category

    A more specific term for an object, more detailed than entry-level.

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    Superordinate-level category

    A more general term for an object, broader than entry-level.

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    Holistic processing

    Recognition based on analyzing the whole object, not just parts.

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    Dynamic face information

    Face features that can change, like expression or shape during speaking.

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    Pandemonium Model

    A model explaining how letters are recognized using processes represented as 'demons'.

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    Early Processing

    The first step in recognition where initial detection occurs.

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    Feature Processing

    Analysis of specific features such as curves or lines in a stimulus.

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    Cognitive Processing

    Matching detected features to templates of known letters.

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    Templates vs Structures

    Templates are fixed representations, while structures are abstract descriptions of parts and relationships.

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    Geons

    Geometric icons used to build perceptual objects.

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    Pros of Templates

    Templates are easy to generate and match but hard to manage due to their quantity.

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    Cons of Structures

    Structures are abstract and generalizable but harder to create specific instances.

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    Study Notes

    Midterm Information

    • Date: February 6th
    • Format: 65 multiple choice questions (MCQ)
    • Materials: Only pencils, erasers, and a water bottle permitted
    • Bags and Jackets: Place bags and jackets at the front of the classroom
    • Assignment: Critical summary assignment due March 27th
    • Format: 4-page writing assignment (plus title page & reference page)
    • Choice: Select one of six articles to summarize and critically analyze
    • Submission: Hand in paper copy at the start of class

    Chapter 4: Perceiving and Recognizing Objects

    • Topic: Visual Processing and Object Recognition
    • Key Concepts: Retinal ganglion cells, LGN, Primary visual cortex, visual areas (V2, V3, V4, V5/MT, Inferotemporal cortex), Extrastriate cortex, boundary ownership cells, dorsal and ventral pathways, inferotemporal cortex, grandmother cell theory

    How Do We Get from Spots to Objects?

    • Retinal ganglion cells and LGN detect spots of light.
    • Primary visual cortex detects bars.
    • There is a progression from spots to bars to more complex objects like cats and dogs.

    Extrastriate Cortex

    • A region of cortex bordering the primary visual cortex
    • Contains multiple areas involved in visual processing, including areas V2, V3, V4, V5/MT, and the inferotemporal cortex.
    • Receptive fields diversify to include more complex properties for object perception (color, texture, etc).

    Example: Boundary Ownership Cells

    • Cells in the extrastriate cortex that respond only if the edge belongs to an object, not the background.

    Dorsal and Ventral Pathways

    • Dorsal Pathway (back): Involved in "where" and "how" aspects of visual processing, focused on the location and shape of objects for action.
    • Ventral Pathway (front): Involved in "what" visual processing, identifying objects and their functions in the environment.

    Inferotemporal Cortex (IT)

    • Important for object recognition.
    • Receptive fields are very large and often cover half the visual field.
    • Respond well to complex stimuli such as hands, faces or objects.

    Quiroga et al. (2005)

    • Recorded electrical activity in homologous regions in humans (Hippocampus and IT cortex)
    • Identified cells that respond selectively to specific objects, such as famous people or images

    Visual Agnosias

    • Prosopagnosia: Difficulty recognising faces.
    • Akinetopsia: Difficulty perceiving motion.
    • Astereognosis: Difficult recognising objects by shape, size, weight, and texture.
    • Alexia: Difficulty with written words (often related to dyslexia).
    • Autopagnosia: Difficulty identifying body parts.
    • Achromatopsia: Difficulty naming colours while being able to see them.
    • Simultagnosia: Difficulty perceiving more than one object at a time.
    • Social-emotional agnosia: Difficulty interpreting nonverbal cues like body language.
    • Form agnosia: Difficulty recognizing an object as whole from its parts.
    • Environmental agnosia: Difficulty identifying locations or giving directions
    • These are all examples of problems that arise when areas responsible for recognising objects are damaged

    Speed of Object Recognition

    • Object recognition happens within 150ms.
    • This requires basic object processing to allow for initial stimulus perception and object name recognition.
    • Implies a feed-forward process which doesn't need feedback between stages

    Reverse-Hierarchy Theory

    • Feed-forward processes initially give crude information about objects using high-level visual cortex.
    • Feedback - the brain asking further questions, allowing for detailed information to become available.
    • This detailed information is retained and processed in lower visual areas through re-entrant processing

    Problems of Object Recognition

    • The challenge of visual perception transforming pixels on a screen into comprehensive objects.
    • The four images depict the same object, but in different positions/angles.
    • How the visual system translates points of light into identifiable objects (e.g. tigers)

    From Spots to Elephants

    • End-stopped cortical cells detect edges
    • Detection of corners and boundaries between objects
    • Determination of surfaces rather than boundaries
    • Differentiating features

    What Even Is an Object ?

    • Examples in different contexts: cats, smells, physical sensations, sounds, events.

    A Trick of the Light

    • Light interaction with surfaces in diverse ways affect how an object is perceived.
    • Specular reflection: Light's reflection from smooth surfaces creates highlights.
    • Matte-surface colour: Some light penetrates, causing absorption and scattering.
    • Translucency: Deeper absorption causes more scattering and apparent glows, resulting in a perception beyond the object's immediate surface

    Subsurface Scattering

    • Different types of light interactions create different appearances. This includes specular reflection(highlights), matte-surface colour (some light penetrates a little way into the object) and translucency (light scatters more widely giving the impression of a glow).

    Structuralism

    • One school of thought that believes complex objects and perceptions can be analyzed into constituent elements
    • Perceptions are considered the sum of sensations (like colour, shape, orientation), not an emergent property. This does not hold up against more complex visual phenomena or processes (like mid-level vision).

    Middle Vision

    • A stage between low-level (basic features extraction from the visual scene) and high-level (object recognition and scene understanding) vision.
    • Focuses on grouping and organising visual elements to identify object boundaries
    • Identifying which edges go together, and the grouping of elements into objects is central

    Finding Edges

    • Computer-based edge detectors are less sophisticated than human vision.
    • Humans are highly sensitive to changes in low-contrast images, defining boundaries even with the same background shading on different parts of the object
    • Illustrates the gaps between image and object detection which computers must contend with. This is the difference between low contrast recognition

    Finding Objects from Lines

    • Unlike computers, humans are not bothered by gaps in edges, allowing for better processing of other visual information.
    • Able to infer missing edge information, thanks to sophisticated pattern identification capabilities.

    Illusory Contours

    • The perception of a contour even though there's no change in the image.
    • These visual phenomena illustrate how the visual system is more than a simple representation of sensory input, offering guesses about what is happening in the visual field

    The Problem with Structuralism

    • Illusory contours highlight the inadequacy of simply trying to combine basic elements to understand vision.
    • Cannot derive the perceived whole from its component parts

    Gestalt

    • Gestalt psychology posits something greater than the sum of its parts—the whole is more than its component parts; a perceived whole cannot be explained by its individual parts.
    • This is a holistic alternative to the atomistic view of structuralism, emphasizing how elements organize into perceived wholes

    Gestalt Grouping Rules

    • Proximity: Objects close together tend to be grouped together.
    • Continuity: Elements arranged along lines or curves are seen as a unit.
    • Closure: The brain fills in gaps to create complete forms
    • Similarity: Similar objects or elements tend to be grouped together; similarities in form, shape, size, colour and orientation
    • Common Fate: Elements moving together are perceived as a group.
    • Symmetry: Ambiguous shapes are perceived as the simplest shape possible

    Continuity

    • Two elements tend to group if they lie on the same contour
    • Illustrates how humans connect more strongly between consecutive elements which are also more proximate

    Continuity and Texture

    • Continuity plays a role in grouping similar visual elements into unified forms even with different shading or absence of clear boundaries.
    • Texture grouping is based on the statistics of textures in a given region, influencing perceived groupings.

    Applying Statistical Analysis to Texture

    • Statistical analyses of textures show how areas differ, indicating separation between textures.

    Similarity and Proximity

    • Similar-looking items tend to be grouped together, often by shape, size, color, or orientation.
    • Items closer to each other are perceived to belong more to the same group

    Camouflage

    • Gestalt principles facilitate object concealment by blending with background patterns.
    • Animals and some military vehicles employ these principles to blend with the surrounding environment to evade detection by others.
    • This is one of the key characteristics of camouflage in both animals and military vehicles

    Ambiguity and Perceptual Committees

    • Vision involves committees incorporating competing principles like proximity, continuity and similarity for consensus-building about the complete image
    • Perception arises from agreements among these principles.

    Ambiguity and Perceptual Committees (continued)

    • Ambiguous figure: Stimulus with multiple interpretations, like the Necker cube.
    • Accidental viewpoint: Regularities may arise in the visual image from a particular viewing position, yet those factors aren't inherent in the real world.
    • Perceptual committees assume viewpoint isn't accidental and interpret based on prior experience and expectation.

    Necker Cube

    • A classic example of a visual stimulus able to be perceived in different ways

    Accidental Viewpoint

    • Visual system doesn't rely on accidental viewpoints, recognizing objects regardless of angle or position,

    Assumptions are Good

    • Explicit knowledge: Easily verbalized knowledge (e.g., directions).
    • Implicit knowledge: Difficult-to-verbalize knowledge (e.g., balance on a bike) used to make assumptions about the world.
    • Assumptions resolve visual ambiguity and help us interpret visual information efficiently.
    • Assumptions aren't foolproof, failing when expectations are violated (e.g., unusual lighting)

    Figure and Ground

    • The process of determining which areas of an image depict the foreground (figure) and background (ground).
    • Principles like surroundedness, size and symmetry guide this process.

    Figure and Ground (continued)

    • Most people perceive the dark pink heart as the figure and the lighter pink background as the ground because it is the most commonly encountered
    • surroundedness, size and symmetry

    Figure-Ground Assignment Principles

    • Surroundedness: The surrounding area is typically the ground,
    • Size: Smaller region is more likely to be the figure.
    • Symmetry: Symmetrical regions are often grouped as the figure. These visual principles influence how we perceive objects.

    Figure-Ground Assignment Principles (continued)

    • Parallelism: Similar lines often are perceived as being part of the same figure
    • Relative Motion: An object moving in front of another is often perceived as the figure

    Law of Common Fate

    • Objects moving together are seen as part of a single unit, often based on a shared motion or direction
    • Illustrates how motion is important in perception.

    Laws of Closure and Symmetry

    • The brain completes incomplete images and objects and often takes the simplest solution

    The Problem of Occlusion

    • Inconsistent visual elements
    • Continuity helps to create understanding even when some visual cues are hidden

    The Problem of Occlusion (continued)

    • Objects partially hidden from view can still be recognised due to prior knowledge or expectations about their shape or physical relationships

    T and Y Junctions in Occlusion

    • T junctions indicate occlusion, with the top of the T usually being in front, and the lower part behind.
    • Y junctions signify corners facing the observer's direction. Arrow junctions point towards the observer.

    Is It the Whole Picture...?

    • Images comprise both global and local elements.
    • Local parts form wholes, and the overall image is also a whole.
    • This demonstrates how the brain combines parts to perceive an overall image rather than simply perceiving individual parts

    Global Superiority Effect

    • Global image is recognised faster than its individual components

    Not All Parts and Wholes Are Simple...

    • The presence of concavities influences recognition, likely due to implicit knowledge about object boundaries.

    From Midlevel Vision to Object Recognition

    • This is the progression of visual processing from low-level to high-level.
      • Early steps focus on lines and edges in specific areas of the visual field.
      • This progresses through steps in V2, V3 and V4 towards full object recognition.

    V4 and Cell Responses in Occluded Shapes

    • V4 cells respond more strongly to specific shapes, rather than to occluded shapes
    • This demonstrates the selectivity of neural responses and the processing challenges in recognizing occluded objects

    A Picture of Processing in the Brain

    • Functional brain imaging techniques (like fMRI) identify regions exhibiting differential activity in response to particular stimuli.
    • Subtraction method is used to isolate brain activities related to specific tasks or stimuli by comparing brain images during different conditions.

    Subtraction Method (continued)

    • Comparing brain activity during a specific mental process compared with a baseline without the mental process can reveal brain activation linked to the specific mental process involved

    Decoding Method

    • This technique involves fMRI scans to identify brain activity when people are viewing images and then comparing this with images seen before, to find patterns of brain activity which could then be used to determine what the people were seeing.

    Pandemonium!

    • A model of letter recognition proposed by Oliver Selfridge in 1959, this model is based on the idea that simple features are analyzed first for matching. This involves a hierarchy of "demons" performing corresponding tasks in different stages of recognition to determine the correct match

    Templates vs. Structures

    • Templates: Internal representations or patterns used to directly match incoming visual stimuli.
    • Structures: Object descriptions utilizing part features and relationships

    Pros and Cons of Templates vs. Structures (models for object recognition)

    • Templates: Easy to generate new representations of things, hard to handle variations or mismatches.
    • Structures: Harder to generate new representations; but can recognize new things without too much difficulty despite variations

    Recognition by Components

    • Geons (geometric ions) are basic shapes that combine to generate objects

    Multiple Recognition Committees

    • Several object-recognition processes occur at the same time, operating across levels of categorization.
    • This parallel processing enables quicker and more accurate recognition, offering flexibility for processing diverse recognition types

    The Special Case of Faces

    • Holistic processing is how humans recognize faces holistically rather than through individual parts
    • Subordinate processing is used to recognise a specific person by analysing their unique features.

    Face Processing Needs to be Flexible

    • Some facial information remains constant, but much of it is dynamic, such as emotion or hair style.
    • Subordinate recognition processes are required to handle this dynamic data, which is critical for effective identification of others under varying conditions and circumstances

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    Chapter 4: Perceiving and Recognizing Objects PDF

    Description

    Test your understanding of Gestalt psychology principles and their application in object recognition. This quiz covers key concepts such as Continuity, Closure, and the PANDEMONIUM model, exploring their significance in perceptual organization. Challenge your knowledge on the differences between templates and structures in object recognition.

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