人机交互

Chapter 1:Douglas Engelbart invented the mouse in1964,was first demonstrated at the 1968 conference.

Chapter 2:

What is a framework? P42

A framework is basically a structure that provides a context for conceptualizing something.

We can use these frameworks to: 1、Structure the design process 2、Help us to identify problematic areas within the design 3、Help us to conceptualize the problem space as a whole

Who processes Execution/Evaluation Action Cycle (EEC) and something about it? P42-44

Donald Norman’s (1990) The Design of Everyday Things. According to Norman, The structure of an action has four basic part:

1.Goals: We begin with some idea of what we want to happen; this is our goal.

2.Execution: We must then execute an action in the world.

3.World: To execute and action, we must manipulate objects in the world.

4.Evaluation: Finally, we must validate our action and compare the results with our goal.

And seven stage of action:

1.What we want to happen; 2.Forming intention; 3.Specifying action; 4.Executing action; 5.Perceiving world state; 6.Interpreting perception; 7.Evaluating interpretation.

Gulf of Execution?? P45

Does the interface allows us to carry out the actions required by the intention?(想要的却没有)

Goal = save a file

Intention = use the file menu

Action = click the save option

Is there a save option in the file menu?(出现的变化却不是想要的)存在一定的疑问！！

Interaction Framework?? P46

Abowd and Beale expanded on the EEC to include the system.four main components:

System (S)—Uses its core language (computational attributes related to system state)

User (U)—Uses its task language (psychological attributes related to user state)

Input (I)—Uses its input language

Output (O)—Uses its output language

Mental Models P48-50

A mental model is a cognitive representation of something that defines a logical and believable estimation as to how a thing is constructed or how it functions.

Mental models are(4个特性、需要展开！)

Unscientific—They are often based on guesswork and approximations.

Partial—They do not necessarily describe whole systems, just the aspects that are relevant to the persons who formulate them.

Unstable—They are not concrete formulations, but evolve and adapt to the context.

Inconsistent—They do not necessarily form a cohesive whole; some parts may be incompatible with other parts of the same model.

Personal—They are specific to each individual and are not universal concepts that can be applied generically.

Semantic and Articulatory Distance P53

Semantic Distance:The distance between what people want to do and the meaning of an interface element.

Articulatory Distance:The distance between the physical appearance of an interface element and what it actually means.

Affordances P54

The affordances of some interfaces can be intuitively understood: a steering wheel affords turning, and a door bell affords pushing.

These connections allow us to make predictions about the results of our actions and help us to create usable mental models.

Chapter 3:

User-Centered Design (UCD) P84

Pioneered by Donald Norman’s research laboratory at the University of California at San Diego.

The objective of UCD is to develop a design framework that enables interaction designers to build more usable systems.

ISO Standard—Human Centered Design Processes for Interactive Systems

• Design should emerge from the user’s

– tasks

– goals

– environment

• Focuses on human-centric issues

– cognition

– perception

– physical attributes and conditions

• user

• environment

Interaction Design Models - Discount Usability Engineering (DUE) P95

Nielsen suggested that the number of problems that could be identified from a usability test with n users can be calculated according to the following equation:

N[1-(1-L)n]

where:N= total number of usability problems in a design

L= proportion of usability problems discovered with a single participant

Chapter 5:

Evaluation – Heuristic Evaluation??P172-173

Heuristic evaluations are performed by usability experts using a predetermined set of criteria designed to measure the usability of a proposed design.

In collaboration with Rolf Molich, Jakob Nielsen developed a set of 10 heuristics for interface design

1.Visibility of system status

2.Match between system and the real world

3.User control and freedom

4.Consistency and standards

5.Error prevention

6.Recognition rather than recall

7.Flexibility and efficiency of use

8.Aesthetic and minimalist design

9.Help users recognize, diagnose, and recover from errors

10.Help and documentation

Chapter 6:

Principles of Interaction Design: P194

Design principles can be used to guide design decisions

• Design principles do not prescribe specific outcomes; they function within the context of a particular design project.

• Design principles guide interaction designers and help them make decisions that are based on established criteria

Framework for design principles: P195-196

Comprehensibility Barrier - If the presentation is comprehensible, the comprehensibility barrier will be superseded. This depends on the degree of efficiency/usability in the interface design.

Learnability Barrier – If the interface is comprehensible it will be learnable, there is a direct relationship.

Other Principles of Perception - Screen Complexity P223

• Formula for calculating the measure of complexity

C, complexity of the system in bits

N, total number of events (widths or heights)

m, number of event classes (number of unique widths or heights)

pn, probability of occurrence of the nth event class (based on the frequency of events within that class)

Chapter 7:

GOMS P244

Goal/task models can be used to explore the methods people use to accomplish their goals

• The GOMS model has four components:

Goals - Tasks are deconstructed as a set of goals and subgoals.

Operators - Tasks can only be carried out by undertaking specific actions.

Methods - Represent ways of achieving a goal -Comprised of operators that facilitate method completion

Selection Rules - The method that the user chooses is determined by selection rules

Modeling Structure – Hicks Law P249

Hick’s law can be used to create menu structures

• Hick’s law states that the time it takes to choose one item from n alternatives is proportional to the logarithm (base 2) of the number of choices, plus 1.

• This equation is predicated on all items having an equal probability of being chosen

T = a + b log2(n+ 1)

• The coefficients are empirically determined from experimental design

• Raskin (2000) suggests that a 50 and b 150 are sufficient place holders for “back-of-the-envelope” approximations

•

Physical Models – Fitts’ Law P260

Fitts’ law states that the time it takes to hit a target is a function of the size of the target and the distance to that target

Fitts’ law can be used to determine the size and location of a screen object

MT = a + b log2(A/W + 1)

Where:

A is the amplitude (distance to the target)

W is the width of the target

MT is the movement time

Constants a and b are arrived at by linear regression

Implications of Fitts’ Law P265任选三点

– Large targets and small distances between targets are advantageous

– Screen elements should occupy as much of the available screen space as possible

– The largest Fitts-based pixel is the one under the cursor

– Screen elements should take advantage of the screen edge whenever possible

– Large menus like pie menus are easier to uses than other types of menus.

Limitations of Fitts’ Law P265任选三点

– There is no consistent way to deal with errors

– It only models continuous movements

– It is not suitable for all input devices, for example, isometric joysticks

– It does not address two-handed operation

– It does not address the difference between flexor and extensor movements

– It does not address cognitive functions such as the mental operators in the KLM model

Chapter 8:

What is Usability? What is Usability Testing? P276-277

• The extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use. (ISO standard 9241-11, 1998)

• A usability test is a structured process used to explore the interaction between an objective participant and a proposed design

Advantages and limitations of Usability Testing:

• Advantages

– Minimize help desk calls

– Increase product loyalty

– Provide benchmarks for future products

• Limitations

– Artificial context

– Not definitive of product acceptance

– Skewed sample of users

– Not always efficient

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