©2001 Southern Illinois University, Edwardsville All rights reserved. Today Fun with Icons Thursday Presentation Lottery Q & A on Final Exam Course Evaluations CS 321 Human-Computer Interaction

©2001 Southern Illinois University, Edwardsville All rights reserved. Ethics Epilog: Therac – 25 Linear accelerator to deliver x-rays and electron beams for the treatment of cancer Released in 1985 Third generation machine (Therac-6, Therac-20)

©2001 Southern Illinois University, Edwardsville All rights reserved. Therac-25 : What happened? Normal radiation treatments: 6,000 rads over a 3 week period. Under certain conditions Therac-25 was delivering 60,000 rads during a single session!

©2001 Southern Illinois University, Edwardsville All rights reserved. Therac-25: What went wrong? Paradigm Shift Therac-25 replaced expensive hardware safety interlocks and constraints on prevsious models with software controls Real-time software Design Race condition caused focusing element to be incorrectly set No interface indication of actual hardware settings – must be checked by going into the radiation area Error messages appeared the same regardless of how important Error messages were difficult to understand; needed to consult a manual or call the company for technical help All errors messages could be manually overridden

©2001 Southern Illinois University, Edwardsville All rights reserved. Therac-25: What went wrong? Lack of experience and overconfidence in software controls No user involvement in design or testing Insufficient testing Poor error messages Lack of visibility of hardware settings Lack of constraints Affordance of overrides Poor documentation

©2001 Southern Illinois University, Edwardsville All rights reserved. Final Words Student ACM Membership CACM: Communications of the ACM Online journals and conference papers Free tutorials Job listings Supports your professional organization

©2001 Southern Illinois University, Edwardsville All rights reserved. What Do These Mean? An icons is a small pictographic symbol Intended to quickly convey their essential meaning to the users Icons designed as warning symbols

©2001 Southern Illinois University, Edwardsville All rights reserved. Why Use Icons? Provide imagery for immediate recognition. Recognition over recall To speed search for actions Pictures can be quicker to scan than text Help improve recall. Reduces the need for interpreting text. To save space Valuable screen real-estate To make interfaces less dependent language Universality

©2001 Southern Illinois University, Edwardsville All rights reserved. Disadvantages of Icons Ambiguity Poorly designed symbol can carry multiple meanings Dependence on the user, task, and context Interpretation depends on the association the user makes between the symbol and her background knowledge The symbols must carry meaning with respect to the task The symbols are interpreted differently in different contexts. Some concepts, particularly actions, can be difficult to display pictorially

©2001 Southern Illinois University, Edwardsville All rights reserved. What Do These Mean? Icons from an application Interface Hall of Shame

©2001 Southern Illinois University, Edwardsville All rights reserved. Icons & Information Processing Imagery of an icon must be meaningful to be effective in providing quick recognition Symbols must have a strong, direct association with the desired meaning

©2001 Southern Illinois University, Edwardsville All rights reserved. Icons & Information Processing Shallow & Deep Analysis Shallow analysis is the processing of surface features, such as lines in pictures. Deep analysis is the processing of semantic features, such as meaning and relationship to other concepts Meaningfulness depends on the icon’s ability to provide for a deep analysis.

©2001 Southern Illinois University, Edwardsville All rights reserved. Attributes of Meaningfulness Familiarity – frequency of which something occurs in everyday activities More familiar images/words are easier to recognize Highly familiar images/words may cause confusion –Users must disassociate the common meaning and associate the intended meaning Imagery – the ability of something to elicit an image in one’s mind

©2001 Southern Illinois University, Edwardsville All rights reserved. Imagery: Icons from the DOT

©2001 Southern Illinois University, Edwardsville All rights reserved. Factors that Effect Meaningfulness Context – the overall setting in which an icon is being used. Temperature warning or weather report?

©2001 Southern Illinois University, Edwardsville All rights reserved. Factors that Effect Meaningfulness Function, Task, or Underlying Concept – what is being represented Nouns are generally easier to represent than verbs  Concrete objects are generally easier to represent than actions  Actions must be conveyed through some indirect representation Highly visual tasks are easier to represent

©2001 Southern Illinois University, Edwardsville All rights reserved. Factors that Effect Meaningfulness What about animated icons?

©2001 Southern Illinois University, Edwardsville All rights reserved. Factors that Effect Meaningfulness Representational Forms – representing the underlying concept Concrete representations: direct representation Abstract representations: expression of a quality apart from the object Combination

©2001 Southern Illinois University, Edwardsville All rights reserved. Factors that Effect Meaningfulness Combining text can aid the interpretation of icons Too many icons with text defeats the advantages

©2001 Southern Illinois University, Edwardsville All rights reserved. Factors that Effect Meaningfulness Types of Representational Forms Resemblance icons: direct depiction of underlying concept Exemplar icon: depicts a typical example of concept Symbolic icon: refers to a higher level abstraction than the image itself Arbitrary icon: no relation to the underlying concept

©2001 Southern Illinois University, Edwardsville All rights reserved. Factors that Effect Meaningfulness Which are: Resemblance? Exemplar? Symbolic? Arbitrary?

©2001 Southern Illinois University, Edwardsville All rights reserved. Factors that Effect Meaningfulness Amount of Detail Determining the appropriate amount of detail is important As little as possible but still get the message across More detail requires more mental processing

©2001 Southern Illinois University, Edwardsville All rights reserved. How Do I Draw an Icon? Find an icon editor Icons are a standard 32 X 32 pixels

©2001 Southern Illinois University, Edwardsville All rights reserved. Icon Exercise Get into your Discussion Groups Design Icons for the concepts on the hand-out Do not use any words Draw them each on a separate piece of paper but DO NOT label them. Be sure everyone’s name is on them. Tape them on the board when you are done.