HCI design principles (middle-level)

HCI design principles (middle-level)

Recognize human diversity - no single design will do

user modeling/operator modeling --> task modeling --> interaction modeling

usage profiles (user profiles) - profiles of the age, gender, physical abilities, education culture/ethnic background, training, motivation, goals, personality

different design goals according to user profiles

novice/first time user : only have task knowledge, anxiety

restricting the vocabulary, informative feedback

knowledgeable intermittent user: maintain the task & computer concept, but difficulty

with syntactic knowledge => use recognition rather than recall

expert frequent user: familar to syntactic knowledge, seek to get the work done

rapidly => provide shortcuts & macros

task profiles : task analysis/ task decomposition -- to be lectured later
interaction styles : a comparative overview

Interaction Styles
Styles	advantage	Disadvantage
Menu	shortens learning reduce keystrokes structural guide of decision making use of dialog-management tools easy support of error handling	danger of too many menu items slow frequent users consumes screen space requires rapid display rate
Form Fillin	simplifies data entry requires modest training use of form-management tools	consumes screen space
Command Language	is flexible appeals to power users supports user initiative convenient to create user-defined macro	has poor error handling requires substantial & memorization
Direct Manipulation	presents task concepts visually easy to learn & retain allows errors to bo avoided encourage exploration	hard to program requires graphic display & devices

8 golden rules of dialog design (Shneiderman)

strive for consistency - consistent sequence, identical terminology, consistent command
enable frequent users to use shortcuts - abbreviations, special keys, macros, ..
offer informative feedbacks
design dialog to yield closure - beginning, middle, end
offer simple error handling
permit easy reversal of actions
support internal locus of control - feeling of in charge of the systems
reduce short-term memory load - on-line access to syntactic knowledge

Error preventing design principles (Norman, 1983)

correct matching pairs --- editor provided matching
offer a sequence of steps as a single action
prevent the user from incorrect use of the product such as offering permissible commands