SENG 310 - Lecture 4

14 January 2015

Psychology of Everyday Actions

Falsely blaming yourself
Misconceptions of everyday life
Blaming the wrong cause

The Seven Stages of Action

  1. forming the goal (e.g. thirsty, going to get something to drink)
  2. forming the intention (e.g. get a soda)
  3. specifying the action (e.g. decide to buy from vending machine)
  4. executing the action (e.g. enter number to get drink)
  5. perceiving the state of the world (e.g. machine gave cue something is happening)
  6. interpreting the state of the world (e.g. realize the clunking is a drink falling)
  7. evaluating the outcome (e.g. deciding if user got the correct drink)

Excecution

The execution stages depend on the user's understanding of the system's functionality and how to access that functionality.
The gulf of execution is the difference between the intentions of the person and the perceived, allowable actions, (i.e. do the actions provided by the system match those intended by the person?).

Evaluation

The evaluation stages depend on the user correctly understanding the system's state.
The gulf of evaluation is the amount of effort the user must exert to interpret the system and determine how well the expectation and intentions have been met.

The Seven Stages of Action as Design Aids

How easily can one:

  • determine the function of the device?
  • tell what actions are possible?
  • determine mapping from intention to physical movement?
  • perform the action?
  • tell if the system is in a desired state?
  • determine mapping from system state to interpretation?
  • tell what state the system is in?

Norman’s Principles of Design for Understandability and Usability

Provide a good conceptual model, taking advantage of affordances & constraints.

Make things visible…
The principle of mapping: natural mappings lead to immediate understanding
The principle of feedback: send back to the user information about what action has actually been done

It generally takes 5 or 6 attempts to get something right, a new product will sink or swim in 1 or 2 attempts (e.g. voice messages on cameras and pop machines)

Conceptual models

A conceptual model is the general conceptual framework through which the functionality of an object is presented. A conceptual model is a 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. A good conceptual model allows users to predict the effects of their actions.

The system image describes the physical structure that has been built i.e. the physical characteristics of the application itself (look and feel).
The designer communicates their design model using the system image and any documentation that goes with it. The user's conceptual model is developed through interacting with the system and by reading any accompanying documentation.

Models Based on Activities

Giving Instructions

  • User's give instructions to computer (e.g. tell time, save a file)
  • Benefit is that is provides quick and efficient interations
  • Good for repetitive kinds of actions

Conversing

  • Underlying model of having a conversation with another human
  • Range of simple voice recognition menu-driven systems to complex dialogues (e.g. Clippy, Siri)
  • Allows users, especially novices to ineract in a comfortable way that's more familiar

Manipulating

  • Draging, selecting, opening, closing and zooming
  • Exploit user's knowledge of how they move and manipulate in the physical world
  • 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
Advantages:
  • 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
  • Error messages rarely needed
  • Users can immediately see if their actions are furthering their goals and if not do something else
  • Users experience less anxiety
  • Users gain confidence and mastery and feel in control
Disadvantages
  • 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)
  • Can become screen space ‘gobblers’
  • Moving a mouse around the screen can be slower than pressing function keys to do same actions
Exploring
  • 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

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 specialized 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.

Interface Metaphors

Interface designed to be similar to a physical entity but also has own properties (e.g. desktop metaphor, web portals).
Can be based on activity, object or a combination of both.
Exploit user’s familiar knowledge, helping them to understand ‘the unfamiliar’.
Conjures up the essence of the unfamiliar activity, enabling users to leverage of this to understand more aspects of the unfamiliar functionality.

Advantages
  • Makes learning new systems easier
  • Helps users understand the underlying conceptual model
  • Can be very innovative and enable the realm of computers and their applications to be made more accessible
Disadvantages
  • Break conventional and cultural rules (e.g. recycle bin placed on desktop)
  • Can constrain designers in the way they conceptualize a problem space
  • Conflict with design principles
  • Forces users to only understand the system in terms of the metaphor
  • Designers can inadvertently use bad existing designs and transfer the bad parts over
  • Limits designers’ imagination in coming up with new conceptual models

Assignments

None