Human information processing: Chapters 4-9 Attentional resources Receptors Perception Response selection Response execution Decision making Long-term memory Working memory Controlled system

Cognition Object and pattern perception Working memory Long-term memory Attention and mental resources

Description of the elements of cognition Role in information processing Process/Theory Design implications

Object and pattern perception: Feature analysis Role: bottom up process of extracting information from sensory stimuli Process: Break stimulus into features that are mapped onto stored patterns geons are the basic feature of 3-D objects Unitization=transformation from feature analysis to more global processing

Object and pattern perception: Feature analysis Design implications: Feature compatibility: Preserve curve and diagonal lines in displaying text Upper and lowercase: Upper case for letter features, lower case for words (unitization) Gaps between letter or number strings enhance perception Line drawings may be superior to photo renderings for shape perception

Object and pattern perception Top-down and Bottom-up processing Task, context, and design defines role of each Design to enhance each (e.g., make visible, use redundancy) Icons vs. Text Legibility, discrimination, and interpretation Pro: Universal, space efficient, effective Con: No clear understanding of how to design “good” icons

Working memory Role: Keeps information active while in use Process: Visuospatial sketchpad and phonological loop maintain two types of information Limited by capacity (7±2 chunks) USA, FBI, CIA (3 chunks not 9) Constant rehearsal is needed to retain Limited by time: half life=7 secs for 3 chunks, 70 seconds for 1 chunk

Working memory Design implications Minimize working memory load (timeXchunks) Use redundant sources (text+speech) Exploit chunking Size of item clusters 2376100 OR 237-6100? Use meaningful sequences Letters rather than numbers (1-800-GET-HELP) Separate numbers and letters Minimize confusion Use different memory codes Order text/instructions carefully

Long-term memory Role: Keeps event information and knowledge available for recall over long periods of time Process: Item strength (frequency, recency) Number of associations (associations between items form chunks, which are available for easy recall) Networks of associations (schemas, mental models) Forgetting (weak strength, few associations, interfering associations) Procedural/implicit vs declarative

Long-term memory “We paint the remote past, as it were, upon a canvas in our memory, yet often imagine that we have direct vision of its depths” (W. James) ?? Multiple people - same event Iowa vs. Michigan (1991) Motor Vehicle Accidents Tragedies Regan being shot Shuttle Challenger Sept. 11th

Long-term memory Design implications Encourage regular use (frequency, recency) Standardize (frequency, recency) Memory aids (supplement LTM) Carefully designed information (limit LTM dependence, support associations) Develop correct mental models (Information processing model for designers, Rankine cycle for NPP controllers)

Attention and mental resources Role: Attention is required to support most cognitive activities (not LTM or sensory registers) Process: Selective, Focussed, and Divided attention (e.g., cocktail party phenomenon, search light) Automatic and controlled processing (e.g.,manual transmission and learning to drive)

Attention and mental resources Process: Multiple Resources Modality (auditory vs. visual, verbal vs. motor) Code (spatial vs. verbal) Stages (perceptual/cognitive vs response)

Modes, codes, and stages in cognitive processing

Attention and mental resources Design implications Design to engage different attentional resources (e.g, voice dial rather manual on car phone) Facilitate timesharing by making tasks automatic (e.g., consistent mapping such as red for stop in driving) Provide information regarding importance to guide people in allocating resources to tasks (e.g., design tone urgency to match message urgency)

Key concepts Cognition can be divided into processes each of which has implications for design Effective perception depends on bottom-up and top-down processing Working memory is limited and volatile Chucking makes working memory effective Long-term memory depends on associations and schema Attention is composed of multiple resources