Interaction Gavin Sim HCI Lecture 4 - 2010/111. Aims of this lecture Last week focused on persona...
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Transcript of Interaction Gavin Sim HCI Lecture 4 - 2010/111. Aims of this lecture Last week focused on persona...
Aims of this lectureLast week focused on persona
and scenario creation.This weeks aims are:
◦To introduce Interaction as a concept that links the human and the computer
◦To begin to consider designing interaction
HCI Lecture 4 - 2010/11 2
Inter - Action
A system is INTERACTIVE if a human user acts with the system in such a way that the system responds in an ACTIVE way depending on the ACT of the human user
HCI Lecture 4 - 2010/11 3
Humans INTERACT with computers in different ways
Touch◦Key presses◦Touch gestures
Voice◦Speech recognition
Actions◦Body recognition
HCI Lecture 4 - 2010/11 4
Increasing complexity
Multi-Modal InteractionIs where the user can interact
using more than one mode – a classic example is the combination of speech and touch – key pressing and talking at the same time
Example Designing multi-modal
interaction is difficult as there are ‘mode’ errors
HCI Lecture 4 - 2010/11 5
Mode ErrorsWhere the computer (and the
user) are not sure what ‘mode’ a system is in◦Example – the pen as a writing
device in a tablet system and the pen as a pointing device (opening up menus) in the same system
◦Save in speech recognition whilst doing word processing
HCI Lecture 4 - 2010/11 6
Interaction is complex
Norman’s modelGoals: What we
want to happenExecution: Execute
action in the worldWorld: Manipulate
objectsEvaluate: validate
action and compare results with our goal
HCI Lecture 4 - 2010/11 7
Goal
Execution Evaluation
World
Norman’s model
Execution◦Interaction◦Task sequence◦Physical Action
Evaluation◦See◦Evaluate◦Check
HCI Lecture 4 - 2010/11 8
ExecutionForming the IntentionGoals must be transformed into intentions, i.e.,
specific statements of what has to be done to satisfy the goal. E.g., "Make a cup of tea using a Tetley tea bag."
Specifying an Action SequenceWhat is to be done to the World. The precise
sequence of operators that must be performed to effect the intention. E.g., “Boil the kettle....."
Executing an ActionActually doing something. Putting the action
sequence into effect on the world. E.g., actually boiling the kettle.
HCI Lecture 4 - 2010/11 9
EvaluationPerceiving the State of the WorldPerceiving what has actually happened. E.g.,
the experience of taste of the tea. Interpreting the State of the WorldTrying to make sense of the perceptions
available. E.g., Putting those perceptions together to present the sensory experience of a cup of tea.
Evaluating the OutcomeComparing what happened with what was
wanted. E.g., did the cup of tea match up to the requirement of 'a nice drink'?
HCI Lecture 4 - 2010/11 10
Gulf’s of InteractionNorman talks about 2
THE GULF OF EXECUTION: does the system provide actions that correspond to the intentions of the user?
THE GULF OF EVALUATION: does the system provide a physical representation that can be directly perceived and that is directly interpretable in terms of the intentions and expectations of the user?
We don’t know what to doWhat we do doesn’t take us towards our goal We don’t see any feedbackThe feedback we get doesn’t tell us we are
making progressHCI Lecture 4 - 2010/11 11
Interaction is about Goals
Understand the person => Understand the goals => Understand the interaction
HCI Lecture 4 - 2010/11 14
15
Keyboards and KeypadsPrimary mode of text entryBeginners 1 keystroke per
secondAverage office worker 5 strokes
per second (50 words a minute)Rapid data entry can be achieve
if more than one key can be pressed simultaneously◦Can represent entire words◦Court rooms (300 words a minute)
Interacting with computersInteract with computers in a
variety of different waysToday we will focus on keyboard
and pointing devices
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Keyboard LayoutQWERTY Keyboard Christopher
Latham in the 1870’s to prevent keys getting jammed
Used letter pairs far apart thereby increasing finger travel distanceKeyboards on Computers are thus inefficient
Keyboard LayoutDVORAK increase typing from
150 words per minute to 200 for advanced users plus reduce errors
ABCDE in alphabetical order, novices will find keys
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KeysConcave surface and matte finish reduce
finger slipKey presses requires 40- to 125- gram force
and displacement from 1 to 4 millimetersFORCE is importantKey pressed enough emits a light click. This tactile and audible feedback is importantClicks on surface computing important as you do not have tactile feedback
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Keys mobile deviceSome come with full QWERTY
keyboardCan reach input of 60 words per
minute with both thumbs when auto corrects
Numerical keyboards◦Multitap key pressed multiple times
and pause◦Predictive techniques T9 dictionary
based◦LetterWise uses probabilities of
prefixes for example if type th probability e
next letter
MacKenzie, I. S., Kober, H., Smith, D., Jones, T., Skepner, E. (2001). LetterWise: Prefix-based disambiguation for mobile text input. Proceedings of the ACM Symposium on User Interface Software and Technology - UIST 2001, pp. 111-120. New York: ACM
22
Pointing DevicesUseful for 7 types of interaction
(Foley et al 1984)◦Select - from a menu◦Position - drag picture next to text◦Orient - a picture, create motion◦Path - create a curve◦Quantify – specify numeric value e.g.
volume in music◦Gestures – indicate an action to perform◦Text – enter, edit, move
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Pointing DevicesGrouped into:
◦Direct Control◦Indirect Control
Direct Control of on screen surface such as touchscreen or stylus
Indirect Control away from the screen mouse, graphics tablets etc..
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StylusDrawingHandwrite on touch sensitive
deviceNatural way to interactDevice needs training to
recognise hand writingRecently had Vision Objects
collecting samples of hand writing
iPhone vs Wii – text input iPhone 18.5 wpmWii 9.2 wpmHowever – error rates
◦7.7% for the iPhone◦2.8% for Wii
Errors on the iPhone predominantly cause hitting the adjacent key