Gols, cognition, requirements

Gols, cognition, requirements

1. Usability goals

   • effective to use (effectiveness)
   • efficient to use (efficiency)
   • safe to use (safety)
   • have good utility (utility)
   • easy to learn (learnability)
   • easy to remember how to use (memorability)

2. User experience goals

   • satisfying
   • enjoyable
   • fun
   • entertaining
   • helpful
   • motivating
   • aesthetically pleasing
   • supportive of creativity rewarding
   • emotionally fulfilling

3. Heuristics and usability principles

   • Visibility of system status
   • Match between system and the real world
   • User control and freedom
   • Consistency and standards
   • Help users recognize, diagnose, and recover from errors
   • error prevention-where possible prevent errors occurring in the first place
   • Recognition rather than recall
   • Flexibility and efficiency of use
   • Aesthetic and minimalist design
   • Help and documentation

4. Cognition

   • Cognition is what goes on in our heads when we carry out our everyday activities. It involves cognitive processes, like thinking, remembering, learning, daydreaming, decision making, seeing, reading, writing and talking
   • attention
   • perception and recognition
   • memory
   • learning
   • reading, speaking, and listening
   • problem solving, planning, reasoning, decision making
   • Conceptual frameworks
     • mental models
       • What happens when people are learning and using a system is that they develop knowledge of how to use the system and, to a lesser extent, how the system works. These two kinds of knowledge are often referred to as a user's mental model. Having developed a mental model of an interactive product, it is assumed that people will use it to make inferences about how to carry out tasks when using the interactive product. Mental models are also used to fathom what to do when something unexpected happens with a system and when encountering unfamiliar systems. The more someone learns about a system and how it functions, the more their mental model develops.
     • information processing
     • external cognition
       • External cognition is concerned with explaining the cognitive processes involved when we interact with different external representations
       • externalizing to reduce memory load
       • computational offloading
       • annotating and cognitive tracing

5. Requirements

   • functional requirements, which say what the system should do, and non-functional requirements, which say what constraints there are on the system and its development.
     • Functional requirements capture what the product should do. For example, a ~ functional requirement for a smart fridge might be that it should be able to tell when the butter tray is empty.
   • A non-functional requirement for a word processor might be that it must be able to run on a variety of platforms such as PCs, Macs and Unix machines.
   • Data requirements capture the type, volatility, sizelamount, persistence, accuracy, and value of the amounts of the required data.
   • Environmental requirements or context of use refer to the circumstances in which the interactive product will be expected to operate. Four aspects of the environment must be considered when establishing requirements.
     • First is the physical environment such as how much lighting, noise, and dust is expected in the operational environment.
     • The second aspect of the environment is the social environment. The issues raised in Chapter 4 regarding the social aspects of interaction design, such as collaboration and coordination, need to be explored in the context of the current development.
     • The third aspect is the organizational environment, e.g., how good is user support likely to be, how easily can it be obtained, and are there facilities or resources for training?
     • Finally, the technical environment will need to be established: for example, what technologies will the product run on or need to be compatible with, and what technological limitations might be relevant?
   • User requirements capture the characteristics of the intended user group.
   • Usability requirements capture the usability goals and associated measures for a particular product.

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