4.1 Visual Perception and Processing

Vision is a complex process involving the eyes and brain working together. From the cornea focusing light to the visual cortex processing information, each component plays a crucial role in how we perceive the world around us.

Our visual system doesn't just passively receive information. It actively interprets and organizes what we see, using both bottom-up processing of sensory input and top-down influence from our knowledge and expectations. This interplay shapes our visual experience.

Visual System Components and Processes

Components of visual perception

Top images from around the web for Components of visual perception

• 

  How We See | Introduction to Psychology View original

  Is this image relevant?

• 

  Vision | Introduction to Psychology View original

  Is this image relevant?

• 

  14.1 Sensory Perception – Douglas College Human Anatomy and Physiology II (1st ed.) View original

  Is this image relevant?

• 

  How We See | Introduction to Psychology View original

  Is this image relevant?

• 

  Vision | Introduction to Psychology View original

  Is this image relevant?

1 of 3

Top images from around the web for Components of visual perception

• 

  How We See | Introduction to Psychology View original

  Is this image relevant?

• 

  Vision | Introduction to Psychology View original

  Is this image relevant?

• 

  14.1 Sensory Perception – Douglas College Human Anatomy and Physiology II (1st ed.) View original

  Is this image relevant?

• 

  How We See | Introduction to Psychology View original

  Is this image relevant?

• 

  Vision | Introduction to Psychology View original

  Is this image relevant?

1 of 3

• Eye structure
  • Cornea transparent outer layer protects eye and refracts light
  • Lens focuses light onto retina adjusts shape for near or far vision (accommodation)
  • Retina light-sensitive layer contains photoreceptors converts light to neural signals
    • Rods sensitive to low light enable night vision (scotopic vision)
    • Cones color-sensitive active in bright light provide detailed vision (photopic vision)
• Visual pathway
  • Optic nerve carries signals from retina to brain bundled axons of retinal ganglion cells
  • Lateral geniculate nucleus (LGN) relay station in thalamus processes visual information
  • Primary visual cortex (V1) initial cortical processing detects edges and orientations
• Higher-order visual areas
  • V2, V3, V4 process specific aspects like color form and motion
  • Inferotemporal cortex object recognition integrates features into whole objects
  • Parietal cortex spatial processing and attention guides visual-motor coordination

Eye-brain cooperation in vision

• Light enters eye focused on retina through cornea and lens
• Photoreceptors convert light into electrical signals (phototransduction)
• Retinal ganglion cells perform initial processing
  • Center-surround receptive fields enhance contrast detect edges
• Signals travel through optic nerve to LGN
• LGN segregates information into separate channels
  • Magnocellular motion and depth perception (where pathway)
  • Parvocellular color and fine detail processing (what pathway)
• Primary visual cortex (V1) processes basic features
  • Orientation-selective cells respond to specific edge angles (line detectors)
  • Simple and complex cells analyze patterns hierarchical processing
• Higher visual areas process increasingly complex information
  • Ventral stream (what pathway) object recognition and identification
  • Dorsal stream (where pathway) spatial relationships and motion perception

Feature and object recognition

• Feature detection
  • Edge detection identifying boundaries between objects and backgrounds (Marr's theory)
  • Orientation detection recognizing lines and angles (Hubel and Wiesel's work)
  • Color processing analyzing wavelengths of light (trichromatic theory)
• Pattern recognition
  • Gestalt principles organizing visual elements into coherent wholes
    • Proximity grouping nearby elements (forming clusters)
    • Similarity grouping similar elements (shape color texture)
    • Closure filling in gaps to complete shapes (perceiving whole objects)
  • Template matching comparing visual input to stored mental representations (face recognition)
• Object recognition
  • Hierarchical processing combining features into increasingly complex representations (Biederman's recognition-by-components theory)
  • View-invariant recognition identifying objects from different angles (mental rotation)
  • Binding problem integrating separate features into a unified percept (feature integration theory)

Top-down vs bottom-up processing

• Bottom-up processing
  • Data-driven starts with sensory input builds perception from basic features
  • Feature extraction identifying basic visual elements (edges colors shapes)
  • Automatic and rapid processing of visual information (preattentive processing)
• Top-down processing
  • Knowledge-driven influenced by prior experiences and expectations
  • Contextual effects surrounding information affects perception (visual context)
  • Attentional modulation focusing on specific aspects of visual scene (selective attention)
• Interaction between top-down and bottom-up processes
  • Perceptual set expectations influence what we perceive (confirmation bias in vision)
  • Binocular rivalry alternating perception of conflicting visual inputs (bistable perception)
  • Visual search combining bottom-up saliency with top-down goals (feature integration theory)
• Implications for visual perception
  • Visual illusions demonstrate how top-down processes can override bottom-up input (Müller-Lyer illusion)
  • Change blindness failure to notice significant changes in visual scenes (flicker paradigm)
  • Inattentional blindness missing unexpected objects when attention is focused elsewhere (gorilla experiment)