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Visual Perception

The ability of viewers to interpret visual encodings of information and thereby decode information in graphs

Ratios more important than magnitude Most continuous variation in stimuli are perceived in discrete steps

Perceptual Processing​

Two stages process

  1. Parallel extraction of low-level properties of scene
  2. Sequential goal-directed processing

Stage 1: Pre-attentive Processing - Low-level, Parallel​

  • Neurons in eye & brain responsible for different kinds of information
  • Arrays of neurons work in parallel, occurs "automatically" and rapidly
  • Information is transitory, briefly held in iconic store
  • Bottom-up data-driven model of processing
  • Often called "pre-attentive" processing i.e. without need for focused attention

Stage 2: Sequential, Goal-Directed​

  • Splits into subsystems for object recognition and for interacting with environment
  • Independent systems for symbolic object manipulations and for locomotion & action
  • Slow serial processing
  • Involves working and long-term memory

Pre-Attentive Feature Conjunctions​

Most conjunctions are not pre-attentive Exceptions:

  • Spatial conjunctions are often pre-attentive
  • Motion and 3D disparity
  • Motion and colour
  • Motion and shape
  • 3D disparity and colour
  • 3D disparity and shape

Gestalt Grouping Principles​

All else being equal, elements that are related by X tend to be grouped perceptually into higher-order units

  • Proximity: Things close together are perceptually grouped together
  • Similarity: Similar elements get grouped together
  • Connectedness: Connecting different objects by lines unifies them
  • Continuity: More likely to construct visual entities out of smooth, continuous visual elements
  • Symmetry: Symmetrical patterns are perceived more as a whole
  • Closure: A closed contour is seen as an object
  • Figure/Ground: Figure is foreground, ground is behind
  • Common Fate (Synchrony): Elements that move in the same direction are perceived as more related

Change Blindness​

  • Dont always see everything that is there
  • Is the viewer able to perceive changes between two scenes?