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www.dadda.it roberto@dadda.it Excellence in usability 1st semester 2021-2022 1
ERGONOMICS APPLIED TO THE DESIGN OF USABLE WEB
PAGES AND APPS
Roberto DADDA and Paolo NEGRI

Artifacts
Interaction design

Interaction design 3

Interaction with word
receptor
affector
mechanism

Don Norman

The seven stages of action (1)
• Forming the Goal
• Something to be achieved. Can be stated in a very
imprecise way, e.g., "make a nice meal“
• Forming the Intention
• Goals must be transformed into intentions, i.e., specific
statements of what has to be done to satisfy the goal. E.g.,
"Make a chicken casserole using a can of prepared sauce.“
• Specifying an Action Sequence
• What is to be done to the World. The precise sequence of
operators that must be performed to effect the intention.
E.g., "Defrost frozen chicken, open can, ...“
• Executing an Action
• Actually doing something. Putting the action sequence
into effect on the world. E.g., “actually opening the can”
2
1
3
4

The seven stages of action (2)
• Perceiving the State of the World
• Perceiving what has actually happened. E.g., “the
experience of smell, taste and look of the the
prepared meal”.
• Interpreting the State of the World
• Trying to make sense of the perceptions available.
E.g., “Putting those perceptions together to
present the sensory experience of a chicken
casserole”.
• Evaluating the Outcome
• Comparing what happened with what was
wanted. E.g., “did the chicken casserole match up
to the requirement of 'a nice meal?”
5
6
7

How do we make things?
Set
goal
Form intention
Specify actions
Execute actions
Get status of word
Understand status
Evaluate outcome

Set
goal
Form intention
Specify actions
Execute actions
Get status of word
Understand status
Evaluate outcome
W
HAT SHOULD
I
DO?
W
HAT IS
HAPPENING?

Set
goal
Form intention
Specify actions
Execute actions
Get status of word
Understand status
Evaluate outcome

Objective of good design
• Help users cross the two gulfs
• Without manuals!

When a device as simple as a
door has to come with an
instruction manual—even a
one-word manual—then it is a
failure, poorly designed.
Donald Norman
Not always possible, but is a good target!
Minimize needs for help!

Help vs manuals
• Help is when I get info during the process
• Manual is something I’m supposed to read before and it is not context
sensitive

Sony – 65 buttons!

grandmother duck mode

Affordance
Interaction design
An affordance is a
property of an object, or
an environment, which
allows an individual to
perform an action. For
example, a knob affords
twisting, and perhaps
pushing, while a cord
affords pulling.
Vital instrument to help customer to cross
easily the gulf of evaluation.
Evaluation makes by feedback analysis
easier the execution!

Interaction design WEB DESIGN NABA 2014 Roberto DADDA 18

Buttons

More an assistant than a guide
Microsoft
BOB,
1995
Microsoft
Office,
1995

The ISO Dialogue Principles
• ISO9241-10
24

Suitability for the Task
• A dialog supports suitability for the task, if it supports the user in the
effective and efficient completion of the task. The dialog presents
the user only those concepts which are related to the user's task.

Self-Descriptiveness
• A dialog supports self-descriptiveness, if each dialog step is
immediately comprehensible through feedback from the system or is
explained to the user on his or her requesting the relevant
information.
Microsoft Word for WindowsT

Controllability
• A dialog supports controllability, if the user is able to maintain
direction over the whole course of the interaction until the point at
which the goal has been met.

Conformity with User Expectations
• A dialog supports conformity with user expectations, if it corresponds
to the user's task knowledge, education, experience, and to
commonly held conventions.

Error Tolerance
• A dialog supports error tolerance if, despite evident errors in input,
the intended results may be achieved with either no or minimal
corrective action having to be taken. Errors should be explained to
the user for him or her to correct them.

Suitability for Individualization
• A dialog supports suitability for individualization, if the dialog system
is constructed to allow for modification to the user's individual
needs and skills for a given task.
30

Suitability for Learning
• A dialog supports suitability for learning, if it guides the user through
the learning stages minimizing the learning time.
31

Choose the best (1)

34

Choose the best (2)

Usability
Roberto DADDA
roberto@dadda.it
www.dadda.it
Skype, Facebook e Twitter robertodadda

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