human factors 03

8/8/2019 Human Factors 03

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human-centered design

Human factors within interactive

digital media design & software

Nick Clarke

Lecturer in CAD for Fashion and Textiles

University of ManchesterSchool of Materials

Faculty of Engineering and Physical SciencesSchool of Materials

Department Fashion and Textiles


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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

lecture: overview


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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 task (educational, navigational, instructional etc.), the

better the user outcomes (ie. learning)

HUMAN-CENTERED DESIGN MATTERS


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human factors: memory systems


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memory: sensory

Memory system that supports momentary storage oflarge

amounts of information gathered by our senses (echoic, iconic,

haptic etc.)

Data is stored in sensory registers fora brief period of time (under 5 sec.).

This is enough time to either react or

attend to critical information.

Most data, however, is discarded.


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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.


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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 providestrategies for encoding information

in such a way that it can later be

recalled and applied in novel

situations.


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sensory memory: processing

Sensory memory facilitates feature analysis and patternrecognition which allows us to recognize friends andfriendly user interface elements

Recognition involves both bottom-up processing and top-downprocessing

Perception is based upon bottom-up processing and helps us todistinguish between data elements.

Top-down processing provides interpretations of data. These arecoloured by our understandings of specific contexts andenvironments.


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processes ofperception

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


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sensory memory: processing & interpretation

ex.jumping to conclusions


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feature analysis: design implications

use contrast and size to bringout salient features of lettersand objectsEx. page background

clearly delineated edges help

feature analysis - line drawingsand line-based icons are morequickly processed than tonalimages

leverage feature compatibility are icons and fonts compatiblewith expectations?Ex. typography

Icons and user interfaceelements should match a giveninterface context


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Advantages:

they are recognized as quickly as words

they support dual encoding

as visual representations

and semantically

Disadvantages:

difficul

t to devel

op universall

y recognised icons difficult to develop a series of clear, distinct icons to represent

different content and functionality

special issues: icons


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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.


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visualsearch & detection

Understanding how humans search and detect visualinformation suggests strategies for interface and graphicdesign

Humans use Parallel and Serial recognition. Ex: Where's Wally?

There is strong evidence that Humans tend to search throughelements on a screen in a serial fashion looking for a target.

Ex. Woodman, G.F, & Luck S.J. (1999) Research

The time it takes to locate a target (the desired menu item, pagecontent 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 locatedfaster and elements noticed in parallel.

logical content organization and expectancies.


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visual search: design strategies


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visual search: design strategies


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working memory: model


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working memory: capacity & duration

hgniy


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a f b z e g o y k t v p


The Magic Number Seven Plus

or Minus Two

- George Miller


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b a t p i g d o g a n t


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working memory: considerations

The limits of working memory are 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


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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 throughpoor design and information structures, there will be less

cognitive resources for the actual learning objectives


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variables impacting attention

Automaticity

When a task becomes automatic it requires less in the way of consciouscognitive resources

Automaticity can increase our ability to multitask and attend to larger sets ofinformation

Multiple modalities

It is easier to divide attention between two different modalities (one visual,one aural) than between two distinct information sources presented in thesame modality

Earliest Memories


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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 discreet chunks of

information in memory (remember the magic number 7 +/- 2).

Organize information into meaningful chunks for working memory

The limits of working memory can be extended when the chunks of

information are larger.


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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. fi lling 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.


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long-term memory: design strategies

Pursue designs that leverage shared

schemas or conventions (ex. hyperlinks)

Use conventions and popular standards


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long-term memory: design strategies

If information is to be remembered, make it meaningful

organize into meaningfu l associations.

present in mu ltiple modes so that one can reinforce the other.

design in a manner consistent with existing mental models or pre-existingknowledge.

design information to high light important connections and relationships.

Embed knowledge in the world to support development ofaccurate mental models; use natural mappings


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summary Human Factors implications

Human systems memory, attention, perception provide uniquedesign constraints of which designers should be aware

Simple, commonsensical approaches to interface and informationdesign

avoiding c lutter

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 canfocus on the educational task, the better the outcomes

HUMAN-CENTERED DESIGN MATTERS


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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


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design heuristics: visibility ofsystem status


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design heuristics: control& freedom


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design heuristics: consistency & standards


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design heuristics: error prevention


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design heuristics: flexibility & efficiency of use


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design heuristics: aesthetic & minimalist design


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design heuristics: help & documentation

add help screens where needed


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session five: human factors

THE END


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visualsearch & detectionSerial and Parallel Searching

human factors 03

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