HCI121 II Understanding and Conceptualizing Interaction

• Understanding the problem space

  – What do you want to create?

  – What are your assumptions?

  – Will it achieve what you hope it will?
• A framework for analysing the problem space

  • Are there problems with an existing product?

  • Why do you think there are problems?

  • Why do you think your proposed ideas might be useful?
• Assumptions: realistic or wish list?

  • People want to be kept informed of up-to-date news wherever they are - reasonable

  • People want to interact with information on the move - reasonable

  • People are happy using a very small display and using an extremely restricted interface - not reasonable

  • People will be happy doing things on a cell phone that they normally do on their PCs (e.g. surf the web, read email, shop, bet, play video games) - reasonable only for a very select bunch of users
• From problem space to design space

  • Having a good understanding of the problem space can help inform the design space – e.g. what kind of interface, behavior, functionality to provide

  • But before deciding upon these it is important to develop a conceptual model
• Conceptual model

  • Need to first think about how the system will appear to users (i.e. how they will understand it)

  • A conceptual model is a high-level description of:

  – “the proposed system in terms of a set of integrated ideas and concepts about what it should do, behave and look like, that will be understandable by the users in the manner intended”
• First steps in formulating a conceptual model

  • What will the users be doing when carrying out their tasks?

  • How will the system support these?

  • What kind of interface metaphor, if any, will be appropriate?
• Conceptual models

  • Many kinds and ways of classifying them

  • Here we describe them in terms of core activities and objects

  • Also in terms of interface metaphors
• Conceptual models based on activities

  • Giving instructions

  • Conversing

  • Manipulating and navigating

  • Exploring and browsing
• • Giving instructions

  – issuing commands using keyboard and function keys and selecting options via menus
• • Conversing

  – interacting with the system as if having a conversation
• • Manipulating and navigating

  – acting on objects and interacting with virtual objects
• • Exploring and browsing

  – finding out and learning things
• 1. Giving instructions

  • Where users instruct the system and tell it what to do

  – e.g. tell the time, print a file, save a file

  • Very common conceptual model, underlying a diversity of devices and systems

  – e.g. CAD, word processors, VCRs, vending machines

  • Main benefit is that instructing supports quick and efficient interaction

  – good for repetitive kinds of actions performed on multiple objects
• 2. Conversing

  • Underlying model of having a conversation with another human

  • Range from simple voice recognition menu-driven systems to more complex ‘natural

  language’ dialogues

  • Examples include timetables, search engines, advice-giving systems, help systems

  • Recently, much interest in having virtual agents at the interface, who converse with you,

  e.g. Microsoft’s Bob and Clippy
• Pros and cons of conversational model

  • Allows users, especially novices and technophobes, to interact with the system in a way that is familiar

  – makes them feel comfortable, at ease and less scared

  • Misunderstandings can arise when the system does not know how to parse what the user says

  – e.g. child types into a search engine, that uses natural language the question: “How many legs does a centipede have?” and the system responds:
• 3. Manipulating and navigating

  • Involves dragging, selecting, opening, closing and zooming actions on virtual objects

  • Exploit’s users’ knowledge of how they move and manipulate in the physical world

  • Exemplified by (i) what you see is what you get (WYSIWYG) and (ii) the direct manipulation approach (DM)

  • Shneiderman (1983) coined the term DM, came from his fascination with computer games at the time
• Core principles of DM

  • Continuous representation of objects and actions of interest

  • Physical actions and button pressing instead of issuing commands with complex syntax

  • Rapid reversible actions with immediate feedback on object of interest
• Why are DM interfaces so enjoyable?

  • Novices can learn the basic functionality quickly

  • Experienced users can work extremely rapidly to carry out a wide range of tasks, even

  defining new functions

  • Intermittent users can retain operational concepts over time
• What are the disadvantages with DM?

  • Some people take the metaphor of direct manipulation too literally

  • Not all tasks can be described by objects and not all actions can be done directly

  • Some tasks are better achieved through delegating

  – e.g. spell checking
• 4. Exploring and browsing

  • Similar to how people browse information with existing media (e.g. newspapers, magazines, libraries, pamphlets)

  • Information is structured to allow flexibility in way user is able to search for information

  – e.g. multimedia, web
• Conceptual models based on objects

  • Usually based on an analogy with something in the physical world

  • Examples include books, tools, vehicles

  • Classic: Star Interface based on office objects

  Another classic: the spreadsheet

  (Bricklin)

  • Analogous to ledger

  sheet

  • Interactive and

  computational

  • Easy to understand
• Which conceptual model is best?

  • Direct manipulation is good for ‘doing’ types of tasks, e.g. designing, drawing, flying, driving, sizing windows

  • Issuing instructions is good for repetitive tasks, e.g. spell-checking, file management

  • Having a conversation is good for children, computer-phobic, disabled users and specialised applications (e.g. phone services)

  • Hybrid conceptual models are often employed, where different ways of carrying out the same actions is supported at the interface - but can take longer to learn
• Conceptual models: from interaction mode to style

  • Interaction mode
  • Interaction style
• • Interaction mode:

  – what the user is doing when interacting with a

  system, e.g. instructing, talking, browsing or other
• • Interaction style:

  – the kind of interface used to support the mode, e.g.

  speech, menu-based, gesture
• Many kinds of interaction styles available…

  • Command

  • Speech

  • Data-entry

  • Form fill-in

  • Query
• Which interaction style to choose?

  • Need to determine requirements and user needs

  • Take the budget and other constraints into account

  • Also will depend on suitability of technology for activity being supported