Human Computer Interface Unit-2

UNIT-II

HUMAN INTERACTION WITH COMPUTERS

Understanding How People Interact with Computers Characteristics of computer systems, past and present, that have caused, and are causing, people problems. We will then look at the effect these problems have –

• Why people have trouble with computers
• Responses to poor design
• People and their tasks

Why People Have Trouble with Computers

• Extensive technical knowledge but little behavioral training.
• With its extensive graphical capabilities.
• Poorly designed interfaces.
• What makes a system difficult to use in the eyes of its user?
• Use of jargon
• Non-obvious design
• Fine distinctions
• Disparity in problem-solving strategies
• an "error-preventing" strategy
• Design inconsistency

PSYCHOLOGICAL

Typical psychological responses to poor design are:

• Confusion: Detail overwhelms the perceived structure. Meaningful patterns are difficult to ascertain, and the conceptual model or underlying framework cannot be understood or established.
• Annoyance: Roadblocks that prevent a task being completed, or a need from being satisfied, promptly and efficiently lead to annoyance. Inconsistencies in design slow computer reaction times, difficulties in quickly finding information, out dated information, and visual screen distractions are a few of the many things that may annoy users.
• Frustration: An overabundance of annoyances, an inability to easily convey one's intentions to the computer, or an inability to finish a task or satisfy a need can cause frustration. Frustration is heightened if an unexpected computer response cannot be undone or if what really took place cannot be determined: Inflexible and unforgiving systems are a major source of frustration.
• Panic or stress: Unexpectedly long delays during times of severe or unusual pressure may introduce panic or stress. Some typical causes are unavailable systems or long response times when the user is operating under a deadline or dealing with an irate customer.
• Boredom: Boredom results from improper computer pacing (slow response times or long download times) or overly simplistic jobs.
• These psychological responses diminish user effectiveness because they are severe blocks to concentration.
• Thoughts irrelevant to the task at hand are forced to the user’s attention, and necessary concentration is impossible.
• The result, in addition to higher error rates, is poor performance, anxiety, and dissatisfaction Physical.
• Psychological responses frequently lead to, or are accompanied by, the following physical reactions.
• Abandonment of the system: The system is rejected and other information sources are relied upon. These sources must, of course, be available and the user must have the discretion to perform the rejection.
• In business systems this is a common reaction of managerial and professional personnel. With the Web, almost all users can exercise this option.
• Partial use of the system: Only a portion of the system's capabilities are used, usually those operations that are easiest to perform or that provide the most benefits. Historically, this has been the most common user reaction to most computer systems. Many aspects of many systems often goon used.
• Indirect use of the system: An intermediary is placed between the would-be user and the computer. Again, since this requires high status and discretion, it is another typical response of managers or others with authority.
• Modification of the task: The task is changed to match the capabilities of the system. This is a prevalent reaction when the tools are rigid and the problem is unstructured, as in scientific problem solving.
• Compensatory activity: Additional actions are performed to compensate for system inadequacies. A common example is the manual reformatting of information to match the structure required by the computer. This is a reaction common to workers whose discretion is limited, such as clerical personnel.
• Misuse of the system: The rules are bent to shortcut operational difficulties. This requires significant knowledge of the system and may affect system integrity.
• Direct programming: The system is reprogrammed by its user to meet specific needs. This is a typical response of the sophisticated worker.
• These physical responses also greatly diminish user efficiency and effectiveness. They force the user to rely upon other information sources, to fail to use a system's complete capabilities, or to perform time-consuming "work-around" actions

IMPORTANT HUMAN CHARACTERISTICS IN DESIGN

Importance in design is perception, memory, visual acuity, fovea and peripheral vision, sensory storage, information processing, learning, skill, and individual differences.

• Perception
• Proximity
• Similarity
• Matching patterns
• Succinctness
• Closure
• Unity
• Continuity
• Balance
• Expectancies
• Context
• Signals versus noise

Memory: Memory is not the most stable of human attributes, as anyone who has forgotten why they walked into a room, or forgotten a very important birthday, can attest.

• Short-term, or working, memory.
• Long-term memory
• Mighty memory
• Sensory Storage

Mental Models: As a result of our experiences and culture, we develop mental models of things and people we interact with.

A mental model is simply an internal representation of a person's current understanding of something. Usually a person cannot describe this mental mode and most often is unaware it even exists.

Mental models are gradually developed in order to understand something, explain things, make decisions, do something, or interact with another person.

Mental models also enable a person to predict the actions necessary to do things if the action has been forgotten or has not yet beaten countered.

Movement Control: Once data has been perceived and an appropriate action decided upon, a response must be made.

In many cases the response is a movement. In computer systems, movements include such activities as pressing keyboard keys, moving the screen pointer by pushing a mouse or rotating a trackball, or clicking a mouse button

THE IMPLICATIONS IN SCREEN DESIGN

• Learning: Learning, as has been said, is the process of encoding in long-term memory information that is contained in short-term memory.
• It is a complex process requiring some effort on our part. Our ability to learn is important-it clearly differentiates people from machines.
• Given enough time people can improve the performance in almost any task. Too often, however, designers use our learning ability as an excuse to justify complex design.
• A design developed to minimize human learning time can greatly accelerate human performance.
• People prefer to stick with what they know, and they prefer to jump in and get started. Unproductive time spent learning is something frequently avoided.
• Skill: The goal of human performance is to perform skillfully. To do so requires linking inputs and responses into a sequence of action. The essence of skill is performance of actions or movements in the correct time sequence with adequate precision. It is characterized by consistency and economy of effort.
• Economy of effort is achieved by establishing a work pace that represents optimum efficiency.
• It is accomplished by increasing mastery of the system through such things as progressive learning of shortcuts, increased speed, and easier access to information or data.
• Skills are hierarchical in nature, and many basic skills may be integrated to form increasingly complex ones. Lower-order skills tend to become routine and may drop out of consciousness.
• System and screen design must permit development of increasingly skillful performance.
• Individual Differences: In reality, there is no average user. A complicating but very advantageous human characteristic is that we all differ-in looks, feelings, motor abilities, intellectual abilities, learning abilities and speed, and soon.
• In a keyboard data entry task, for example, the best typists will probably be twice as fast as the poorest and make 10 times fewer errors.
• Individual differences complicate design because the design must permit people with widely varying characteristics to satisfactorily and comfortably learn the task or job, or use the Website.
• In the past this has usually resulted in bringing designs down to the level of lowest abilities or selecting people with the minimum skills necessary to perform a job.
• But technology now offers the possibility of tailoring jobs to the specific needs of people with varying and changing learning or skill levels. Multiple versions of a system can easily be created.
• Design must provide for the needs of all potential users

HUMAN CONSIDERATIONS IN DESIGN

• The knowledge possessed by a person, and the experiences undergone, shape the design of the interface in many ways. The following kinds of knowledge and experiences should be identified.
• Computer Literacy - Highly technical or experienced, moderate computer experience, or none
• System Experience - High, moderate, or low knowledge of a particular system and its methods of interaction
• Application Experience - High, moderate, or low knowledge of similar systems

HUMAN CONSIDERATIONS IN DESIGN

• Task Experience - Other Level of knowledge of job and job tasks
• Systems Use - Frequent or infrequent use of other systems in doing job
• Education - High school, college, or advanced degree
• Reading Level - Less than 5th grade, 5th-12th, more than 12thgrade
• Typing Skill - Expert (135 WPM), skilled (90 WPM), good (55 WPM), average (40 WPM), or "hunt and peck" (10WPM).
• Native Language or Culture- English, another, or several.

JOB/TASK/NEED

• Type of System Use - Mandatory or discretionary use of the system.
• Frequency of Use - Continual, frequent, occasional, or once-in-a-lifetime use of system.
• Task or Need importance - High, moderate, or low importance of the task being performed.
• Task Structure - Repetitiveness or predictability of tasks being automated, high, moderate, or low.
• Social Interactions - Verbal communication with another person required or not required.
• Primary Training - Extensive or formal training, self training through manuals, or no training.
• Turnover Rate - High, moderate, or low turnover rate for jobholders
• Job Category - Executive, manager, professional, secretary, clerk
• Lifestyle - For Web e-commerce systems, includes hobbies, recreational pursuits, and economic status

PSYCHOLOGICAL CHARACTERISTICS

• Attitude - Positive, neutral, or negative feeling toward job or system.
• Motivation - Low, moderate, or high due to interest or fear.
• Patience - Patience or impatience expected in accomplishing goal.
• Expectations - Kinds and reasonableness.
• Stress Level - High, some, or no stress generally resulting from task performance.
• Cognitive Style - Verbal or spatial, analytic or intuitive, concrete or abstract.

PHYSICAL CHARACTERISTICS

• Age Young middle aged or elderly.
• Gender Male or Female.
• Handiness Left, right or ambidextrous.
• Disabilities Blind, defective vision, deafness, motor handicap.

HUMAN INTERACTION SPEEDS

• The speed at which people can perform using various communication methods has been studied by a number of researchers.
• Reading: The average adult, reading English prose in the United States, has a reading speed in the order of 250-300 words per minute. Proof reading text on paper has been found to occur at about 200 words per minute, on a computer monitor, about 180 words per minute.
• One technique that has dramatically increased reading speeds is called Rapid Serial Visual Presentation, or RSVP. In this technique single words are presented one at a time in the center of a screen. New words continually replace old words at a rate set by the reader. For a sample of people whose paper document reading speed was 342 words per minute? (With a speed range of 143 to 540 words per minute.) Single words were presented on a screen in sets at a speed sequentially varying ranging from 600 to 1,600 words per minute. After each set a comprehension test was administered.

READING

• Prose text - 250-300 words per minute.
• Proof reading text on paper - 200 words per minute.
• Proofreading text on a monitor - 180 words per minute.

LISTENING

• Speaking to a computer: 150-160 words per minute.
• After recognition corrections: 105 words per minute.

KEYING

• Typewriter
• Fast typist: 150 words per minute and higher Average typist: 60-70 words per minute
• Computer
• Transcription: 33 words per minute Composition: 19 words per minute
• Two finger typists
• Memorized text: 37 words per minute Copying text: 27 words per minute
• Hand printing
• Memorized text: 31 words per minute. Copying text: 22 words per minute.

UNDERSTAND THE BUSINESS JUNCTIONS

• Business definition and requirements analysis
• --Direct methods
• --Indirect methods
• --Requirements collection guidelines
• Determining basic business functions
• --Developing conceptual modes
• --Understanding mental models
• --Users new mental model
• Design standards or style guides
• --Value of standards and guidelines
• --Document design
• --Design support and implementation
• System training and documentation
• -- Training
• --Documentation

DIRECT METHODS

• Individual Face-to-Face Interview
• Telephone Interview or Survey
• Traditional Focus Group
• Facilitated Team Workshop
• Observational Field Study
• User-Interface Prototyping
• Usability Laboratory Testing
• Card Sorting for Web Sites
• A technique to establish groupings of information for Websites

INDIRECT METHODS

• MIS Intermediary
• Paper Surveyor Questionnaire
• Electronic Surveyor Questionnaire
• Electronic Focus Group
• Marketing and Sales
• Support Line
• E-Mail or Bulletin Board
• User Group
• Competitor Analyses
• Trade Show
• Other Media Analysis
• System Testing

DETERMINING BASIC BUSINESS JUNCTIONS

Major system functions are listed and described, including critical system inputs and outputs. A flowchart of major functions is developed. The process the developer will use is summarized as follows: Gain a complete understanding of the user's mental model based upon:

• The user's needs and the user's profile.
• A user task analysis.
• Develop a conceptual model of the system based upon the user's mental model. This includes:
• Defining objects.
• Developing metaphors