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human-centered design Human factors & interactive digital media design
lecture: overview Focus on human commonalities - memory, perception, and attention Introduce the Information Processing Model of cognition Suggest some human-centered design strategies derived from these understandings and the information processing model
guiding assumptions Human systems – memory, attention, perception – provide some unique constraints of which designers should be aware Simple, commonsensical approaches to interface and information design can make a difference in using with online and offline multimedia environments The more cognitive resources (attention, memory, etc. ) that you can focus on the educational task, the better the learning outcomes – HUMAN-CENTERED DESIGN MATTERS
human factors: Information Processing Model memory systems
memory: sensory Memory system that supports momentary storage of large amounts of information gathered by our senses (echoic, iconic, haptic, etc. ) Data is stored in sensory registers for a brief period of time (under 5 sec. ). This is enough time to either react or attend to critical information. Most data, however, is discarded.
memory: working Working memory provides a temporary workspace for information drawn from the sensory registers and activated from long term memory. This is where thinking occurs. Working memory has a limited storage capacity for information. Information decays quickly without constant rehearsal.
memory: long-term The memory system that supports relatively permanent storage of information is called long-term memory. Long-term memory has unlimited capacity. Learning is about transferring information from working memory into long-term memory. Learning theories provide strategies for encoding information in such a way that it can later be recalled and applied in novel situations.
sensory memory: processing Sensory memory facilitates feature analysis and pattern recognition which allows us to recognize friends and friendly user interface elements Recognition involves both bottom-up processing and top-down processing – Perception is based upon bottom-up processing and helps us to distinguish between data elements. – Top-down procession provides interpretations of data. These are colored by our understandings of specific contexts and environments
processes of perception The act of perception is a fast, but complex task. break down complex stimuli into simple features extract features from sensory data construct patterns from this information compare patterns with those in long-term memory finding a match = perception
sensory memory: processing & ex. jumping to conclusions interpretation
feature analysis: design implications use contrast and size to bring out salient features of letters and objects Ex. page background clearly delineated edges helps feature analysis - line drawings and line-based icons are more quickly processed than tonal images leverage feature compatibility – are icons and fonts compatible with expectations Ex. typography Icons and user interface elements should match a given interface context
special issues: icons Advantages: – they are recognized as quickly as words – they support dual encoding as visual representations and semantically Disadvantages: – difficult to develop universally recognized icons – difficult to develop a series of clear, distinct icons to represent different content and functionality
rules of thumb: icons Use labels with icons. Icons should be distinct to aid memory. Clear, simple icons are often more easily interpreted than complex, 3 -D tonal icons.
visual search & detection Understanding how humans search and detect visual information suggest strategies for interface and graphic design – Humans tend to search through elements on a screen in either a serial or parallel fashion looking for a targets The time it takes to locate a target (the desired menu item, page content, etc. ) depends upon a few variables: – The number of items on a screen – serial search; Neisser: T=(NI)2 – Element conspicuity – parallel; things that stand out are located faster and elements noticed in parallel – logical content organization and expectancies
visual search: design strategies
visual search: design strategies
working memory: model
working memory: capacity & duration hgniy
working memory: capacity & duration afbzegoyktvp The Magic Number Seven – Plus or Minus Two - George Miller
working memory: capacity & duration batpigdogant
working memory: considerations The limits of working memory is an impediment to learning – educational content – navigational structures – computer environments and interfaces Instructional and interface designs, content organization and site architecture should account for these limitations and potentials
focus on attention Information processing relative to learning requires a great degree of attention and cognitive resources Like working memory, human attention is limited Multitasking or splitting attention often causes a drop in performance of all tasks involved If the majority of participants’ attention is consumed by the mechanics of your screen environment or wading through poor design and information structures, there will be less cognitive resources for the actual learning objectives.
variables impacting attention Automaticity – When a task becomes automatic it requires less in the way of conscious cognitive resources – Automaticity can increases our ability to multitask and attend to larger sets of information Multiple modalities – It is easier to divide attention between two different modalities (one visual, one aural) than between two distinct information sources presented in same modality – Earliest Memories
working memory: design strategies Minimize the load on working memory for learning activities design user interfaces, interactive modules, and learning materials so that participants are not required to hold large numbers of discrete chunks of information in memory (remember the magic number 7 +- 2) Organize information into meaningful chunks for working memory The limits are working memory can be extended when the chunks of information are larger
working memory: design strategies
working memory: design strategies
long-term memory: conceptual structures Information is organized into associative networks (schemas) Schemas reflect central ideas or concepts – Ex. What a web site is, a college campus, etc. Scripts are schemas describing sequences of actions – Ex. filling out & submitting a form on the web, navigating through a web site using hypertext links, driving a car to class, dining in a restaurant, etc. Mental models are schemas of dynamic systems, objects & equipment – Ex. VCRs, interactive web environments, etc.
long-term memory: design strategies Use conventions and popular standards Pursue designs that leverage shared schemas or conventions (ex. hyperlinks)
long-term memory: design strategies If information is to be remembered, make it meaningful. – organize into meaningful associations – present in multiple modes so that one can reinforce the other – design in a manner consistent with existing mental models or pre-existing knowledge – design information to highlight important connections and relationship Embed knowledge in the world to support development of accurate mental models; use natural mappings
summary Human Factors implications Human systems – memory, attention, perception – provide unique design constraints of which designers should be aware Simple, commonsensical approaches to interface and information design – – avoiding clutter making things distinct and visible reducing cognitive load from extraneous information Designing interfaces to accommodate human expectations of the web can make a difference in learning from web-based environments The more cognitive resources (attention, memory, etc. ) that you can focus on the educational task, the better the outcomes – HUMAN-CENTERED DESIGN MATTERS
human-centered principles & interface design Interface – Mediator between a user and the underlying system or environment – Can either facilitate or inhibit use depending upon how well they incorporate human-centered principles
design heuristics Jakob Nielsen 10 Design Heuristics – – – – – Visibility of system status Match between system and real world User control and freedom Consistency and standards Error prevention Recognition rather than recall Flexibility and efficiency of use Aesthetic and minimalist design Help users recognize, diagnose and recover from errors Help and documentation
design heuristics: visibility of system status
design heuristics: control & freedom
design heuristics: consistency & standards
design heuristics: error prevention
design heuristics: flexibility & efficiency of use
design heuristics: aesthetic & minimalist design
design heuristics: help & documentation add help screens where needed