2.2 Preattentive Processing and Visual Hierarchy

Visual perception plays a huge role in how we process info. Our brains quickly notice certain visual cues without us even thinking about it. This helps us spot important stuff fast, like finding Waldo in a crowded scene.

Designers use these perception tricks to guide our eyes and organize info. They make key things pop out and group related stuff together. This creates a visual hierarchy that tells our brains what to focus on first.

Preattentive Processing

Preattentive Attributes and Pop-Out Effect

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• Preattentive attributes are visual properties processed rapidly and automatically by the low-level visual system before conscious attention
• Include color, size, shape, orientation, motion, and spatial position
• Enable viewers to detect information quickly without focusing attention on individual elements
• The pop-out effect occurs when a unique visual attribute stands out from surrounding elements and is easily detected (red circle among blue circles)

Visual Search and Feature Integration Theory

• Visual search involves scanning a display for a specific target element among distractors
• In a feature search, the target differs from distractors by a single preattentive attribute and is found quickly regardless of the number of distractors
• In a conjunction search, the target shares attributes with distractors and requires focused attention to locate, with search time increasing as the number of distractors increases
• Feature integration theory proposes that preattentive attributes are processed in parallel, while integrating multiple attributes requires serial attentional processing

Visual Hierarchy

Establishing Visual Hierarchy through Saliency and Contrast

• Visual hierarchy organizes and prioritizes elements in a display based on their relative importance
• Guides viewer's attention and influences the order in which information is processed
• Saliency refers to the distinctiveness of an element relative to its surroundings
• Highly salient elements attract attention and are perceived as more important (large, brightly colored headline)
• Contrast in size, color, or other attributes creates visual hierarchy by emphasizing key elements and de-emphasizing less important ones

Grouping Elements in Visual Hierarchy

• Grouping techniques organize related elements and establish relationships within a hierarchy
• Proximity groups elements placed close together, implying a connection (clustered buttons in a navigation menu)
• Similarity groups elements sharing common attributes, such as color, shape, or size (icons with consistent design)
• Enclosure groups elements contained within a border or background, separating them from other groups (sections in a website layout)
• Effective grouping reduces complexity, enhances understanding, and guides attention within the visual hierarchy

Visual Encoding

Color, Size, and Shape Encoding

• Visual encoding uses visual attributes to represent data or information
• Color encoding assigns meaning to different colors (red for danger, green for success)
• Enables quick identification and categorization of elements
• Size encoding uses relative scale to represent quantitative differences (larger icons for higher values)
• Effectively communicates magnitude and importance
• Shape encoding assigns distinct shapes to different categories or types of information (circles for locations, squares for events)
• Facilitates recognition and differentiation of elements

Proximity Encoding

• Proximity encoding uses spatial position to convey relationships or similarities between elements
• Elements placed closer together are perceived as related or belonging to the same group (navigation links in a horizontal bar)
• Proximity can also imply sequence, hierarchy, or continuity (steps in a process diagram)
• Effective use of proximity reduces clutter, organizes information, and guides the viewer's eye through the display