Theories and Practice of Interactive Media 6 October 2003 Kathy E. Gill

Agenda Review questions Review assignments Shannon (comm models) Human Factors HCI

Questions ?

What is communication? The imparting, conveying or exchanging of ideas, knowledge, etc The transfer of thoughts and messages by sign and sounds

Communication theories Linear or Transmission (Shannon- Weaver, 1948; Lasswell, 1960) Circular (Osgood and Schramm, 1954) Medium Theory (McLuhan et al)

Shannon-Weaver (1/3) Information theory is “exceedingly general in scope, fundamental in the problems it treats, and of classic simplicity and power in the results it reaches” (Shannon & Weaver, 1949) Theory of signal transmission

Shannon-Weaver (2/3)

Shannon-Weaver (3/3) Redundancy is used to offset noise in a channel Noise increases uncertainty What is noise in interactive media?

Osgood and Schramm (1/2) Importance of “meaning” One person can be sender and receiver (feedback) Stresses social nature of communication

Osgood and Schramm (2/2)

Lasswell Formula Who (sender) Says What (message) In What Channel (medium or channel) To Whom (receiver) With What Effect (impact)

Medium Theory Assumes… A process of standardization, such as specific historical eras (e.g. oral, print, and electronic) Relational "effects” on consciousness (e.g. "print creates linearity”) Society is simply a reverberation of the medium From Towards an Ecology of Understanding: Semiotics, Medium Theory, and the Uses of Meaning

Interactive Communication Interaction between senders and receivers humans and machines a message and its consumers

Human Factors: Definition Study of human (or operator)-related factors that promote and facilitate optimal performance

Optimal Performance Reduce errors Increase efficiency Enhance safety Enhance comfort

History Early 20 th Century – time and motion studies

Why Human Factors? Life-critical systems Nuclear reactors, airplanes, submarines Industrial and commercial uses Order entry, billing systems, point-of-sales Office, home,and entertainment systems Electronic mail, ATMs, word processing Exploratory, creative, cooperative systems World Wide Web, automobile dashboard

Relevance and Impact Productivity - People and Systems Call-centers, e-commerce web sites User Perception Tivo v Replay, VCR Plus Training Cost Large component of new implementation Cost of Errors Medical errors, airplane crashes

Inconsistent Message

Can you read this ?

An Engineering Approach (1/3) Concept Determine objectives – clearly identify audience(s) Basic Design Functional specification (hardware, software, human); requirements; task analysis

An Engineering Approach (2/3) Interface Design Apply empirical data, mathematical functions, experience, principles, population measures, and design standards Production Integrate production requirements, test, and update

An Engineering Approach (3/3) Deployment Investigate use, modify, evaluate Follow up Procedures, product evolution

The Challenge Only 28 percent of IT projects are delivered on schedule and within budget Only one-sixth software projects completed on time and within budget

The Challenge, cont’d One-third of complex software projects fail, costing U.S. companies $81 billion Cost overruns add another $59 billion Of the challenged or cancelled projects, the average was 189%over budget, 222% behind schedule and contained only 61% of the originally specified features

Answering the Challenge Projects fail because “the system did not meet user needs” Enter: User-Centered Design Central tenet: who is the audience? Not a “step” but a “process”

Now a Standard: ISO A clear understanding of the ‘context of use’: users, tasks and environment Iteration of design solutions using prototypes Active involvement of real users Multi-disciplinary design

Summary Human factors principles are based on the psychological, biological, and physical strengths and limitations Good interface design enables increase in productivity, reduction in errors, and better user experience The key to good design is customer- focus

Break

Theories in HCI Must explain and predict human behavior in the human-computer system Must work in a wide variety of task situations Must work within broad spectrum of system designs and implementations

Application of theory Some theories can be used to predict human performance Fitt’s law Time to select an item with a pointing device Keystroke level model Sums times for keystroking, pointing, homing, drawing, thinking and waiting

Two general models Stages of interaction (Norman) Norman’s theories are broader than computer systems Syntactic/semantic model (Shneiderman) Object-action interface model

Norman’s seven-stage model Physical activity Execution Action Specification Intention Goals Evaluation Interpretation Perception Mental activity expectation

Simplified four-stage model Intention (goal) Selection (decision) Execution (act!) Evaluation (did it work?)

1. Forming an intention “What we want to happen” Internal mental characterization of a goal May comprise goals and sub-goals (but rarely are they well planned) Similar to task semantics e.g. “send a letter to Aunt Dot” e.g. “record episode of Enterprise”

2. Selecting an action Review possible actions and select most appropriate e.g. “use the word processor to create a file called aunt.dot.letter” e.g. “use the RePlay to record this season’s Enterprise broadcasts”

3. Executing the action: Carry out the action using the computer May be similar to mapping between semantics and computer syntax e.g. type “emacs –nw harriet.letter”

4. Evaluate the outcome Check the results of executing the action and compare it with the expectations e.g. see if word processor is active and verify that file name is “aunt.dot.letter” e.g. see if RePlay is active and verify that Enterprise has been recorded Requires perception, interpretation, and incremental evaluation

A typical task intention-1 intention-2 intention-3 action specification evaluate-1 evaluate-2 evaluate-3 interpretation intention-4 evaluate-4 look better block para.pp->.sp execution perception get formatted output action specification execution interpretation printer perception

Goals Physical System gulf of execution Gulf of Execution Do actions provided by system correspond to the intentions of the user? Gulf: amount of effort exerted to transform intentions into selected and executed actions

A good system Has direct mapping between intention and selections Consider printing a letter: Drag document onto printer icon Select print from menu Type “aunt.dot.letter; lpr -Palw3 latex.dvi”

Goals Physical System gulf of evaluation Gulf of Evaluation Can feedback be interpreted in terms of intentions and expectations? Gulf: amount of effort exerted to interpret feedback

Key to a good system Feedback easily interpreted as task expectations e.g. graphical simulation of text page being printed Alternative: no feedback or difficult to interpret feedback e.g. Unix: “$”, “bus error”, “command not found”

Bridging Gulf of Execution and Evaluation Goals Physical System execution bridge intentions action specifications interface mechanism evaluation bridge interpretations interface display evaluations

Design questions How easily can a user Determine the function of the system? Tell what actions are possible? Determine mapping from intention to selection? Perform the action? Tell what state the system is in? Determine mapping from system state to interpretation? Tell if system is in the desired state?

Norman on Design Visibility Can I see the state of application and my alternatives for actions? Good conceptual model Does the system have consistent presentations of operations and results?

Norman on Design Good mappings What are the relations between Actions and results Controls and their effects System state and what is visible Feedback Full and continuous feedback about results of actions

Principle of transparency “The user is able to apply intellect directly to the task; the tool itself seems to disappear.”

Summary Communication models need to incorporate feedback and intent Interactive systems must minimize the Gulf of Execution and the Gulf of Evaluation in order to be successful Good design considers each of these concepts