Interfacce per umani vicini e lontani

Interfacce per umani
vicini e lontani
Stefano Levialdi
Dipartimento di Informatica
Università di Roma, La Sapienza
interfaces, what for?
 without interfaces computers would be useless
 human-computer interfaces are not even as
carefully designed as computer-computer
interfaces
 computer science has a definite role in the
design of human-computer interfaces
 creativity is very important in the design of user
interfaces
input-output devices
 keyboard - mouse - joystick - monitor
 are not to be confused with the
interface, they may be seen as portals
to the interface program
Jef Raskin’s definition I
 interface: the way that you accomplish
tasks with a product - what you do and
how it responds (1993)
 simple tasks
simple interfaces
 complex tasks
complex interfaces
 VCR watch setting
+ hours + minutes
12:30
- hours - minutes
three key issues
 1-Predictability
 by picking a metaphor that the user
understands,
 then staying consistent with those rules
at all costs.
 predictability eliminates training time
and allows the user to make
associations and jump chasms in selftraining.
second issue
 2-Consistency once you create a behavior
you stick with it.
 all windows or menus behave the same,
 a shortcut key that always does the same
thing (even across programs),
 mouse button or action always do the
same thing; configurability is often
necessary, but is usually the enemy of
predictability and consistency because a
user can change something so that it is no
longer predictable
example
 imagine someone rewired your car so that when
you pushed in the cigarette lighter it would ignite
the car’s gas tank,
 while this might be a nifty option (very James
Bond) it is definitely unpredictable, especially if
there is no warning label. Ironically, your
cigarette WOULD get lit, so the label is
accurate. While you might WANT this feature,
there is very little probability you would like it! it.
third issue
 3-Information
 information display is about how much
information you can get to the user, while still
preserving screen real estate (and not being
cluttered or overly complex),
 this means choosing what is valuable
information and displaying it - and NOT
displaying irrelevant information,
 more is not better, unless you NEED more.
Efficiency and relevancy of the data
presentation are most important.
example
 imagine if everything about your car was displayed in
a myriad of gauges all across your dashboard; even to
the point where it obscured your view (imagine an
airplane cockpit and you get the idea),
 while it might be nice to know what the tire pressure is,
or the relative humidity in the cars trunk, it is not
necessary information. So this information would
merely be available to impress your friends. Not only
is the information useless, the overabundance of
information and clutter would actually hinder you from
getting work done (driving), by blocking your view and
making you search for the information you care about.
 is that the fuel temperature, fuel mixture, fuel
pressure, or just the amount of fuel I have left?
positive features
 Prioritizing - Apple decided that the
information on the screen should be
displayed and positioned by importance.
Immediate actions always appear in the
center of the screen (dialogs/alerts/status). It
is ordered like western reading/writing; upperleft is most important (first), lower-right is
least important.
another feature
 Simplicity: the word speaks for itself.
Never make the user do two steps to
complete an operation when one step will
do. Never ask the user things they don't
care about.
 The other part of simplicity is to avoid
adding so many functions that users can't
remember HOW to do something. Simple
choices, simple methods. KISS!
example
 Example: Imagine if to start your car, you had
to set the manual choke, hand prime the
carburetor, crank a generator while
simultaneously counter cranking a manual
starter. Of course there would be a shortcut
that if you crawled underneath your car, there
would be a “start” button, but that wouldn't be
in the manual.
designing human interfaces
 two sides of the design problem:
1) computer science issues (essentially
programming a chosen set of algorithms
favouring human-program
communication and control) and
2) human issues (essentially exploiting
and supporting user's skills)
on the design...
 user interface design: complexities of the
human-program communication needs +
peculiarities of classes of human users:
they should all be interviewed, understood,
modelled, taken care of, documented,
tested, validated, refined...
the ≠ models
Model of the user
Model of the system
value sensitive design
Gary Chapman 2000
 chief privacy officer
 proprietary calendaring (Microsft, SUN)
 power over design: marks the difference
 expert systems or systems for experts?
(Scandinavian approach)
 web sites & on-line services: “opt-in” or
“opt-out”?
 a technical standard may influence 106
people!
formal approaches
 formal approaches help in abstracting the details
and subtleties of how computers are used;
interface features should not be looked at within
particular applications
undo in an airline reservation system ≠ in
undo in an interactive system
 general rules have been abstracted: low cognitive
load, few basic icons, possibility of undoing all
actions, bactracking availability, on-line help, etc.
usability
 R.B. Miller [Mil71] “a property reflecting the




ease-of-use of an information system”
a broader view [91] “a feature based on 4
basic factors: 1) effectivity, 2) learnability, 3)
flexibility and 4) attitude”
Bevan [Bev93] “the level of efficacy, efficiency
and satisfaction reached by a product which
is employed by a class of users in order to
reach given goals in specific environments”
Standard ISO 9241 (november 1995)
D. Redmiles [Red02] “a property concerning
systems both useful and usable to which users
have the right to access”
a few considerations...
 as far as the user is concerned, the
interface IS the product
 the system should treat all user input as
sacred
 a computer should not waste your time
or require you to do more work than is
strictly necessary
 an interface is humane if it is responsive
to human needs and considerate to
human frailties
cognetics at work
 users should set the pace of an interaction
 know thyself - ergonomics of the mind
 we must deal with unconscious &
conscious cognitive aspects of the human
mind
 different definitions have been coined to
describe these two different cognitive
aspects
locus of attention
 to focus - voluntary action
 locus of attention - might both be voluntary




or unaware
one may concentrate on only 1 locus of
attention
visual perceptions decay in 200 ms
auditory perceptions decay in 1500 ms
not all perceptions become memories
habit formation
 with repetition or practice, competence




becomes habitual
any habit is a surrender of detail control
“to fall into a habit is to begin to cease to
be” - Unamuno
persistent use of an interface will cause to
develop habits...unable to avoid...
create interfaces that do not allow habits
to cause problems to the user
habits & design
 take advantage of human habit formation
 allow users to develop habits that smooth
the workflow
 many ways of accomplishing the same
task: requires the shift of locus of attention
to choose the “best” way
 a habit cannot be undone by any single
act of willpower - retraining is needed
L’insegnamento a distanza è
variegato
 e-learning
 contract learning
 chunk learning
 blended learning
 CoD - contents on demand
 role playing simulation…
Aumento di studenti a distanza
(in US)
# U.S.
students
?
106
2x106
2001
2002
2003
Mercato dell’e-learning in
Italia
350
297,1
300
250
191
200
150
120,6
100
74,8
45,8
50
19
29
0
2000
-01
- 02
-03
-04
-05
-06
Le tre comunità
docenti
amministrativi
studenti
Differenze con la didattica
tradizionale
 Al centro dell’attenzione non c’è più il
soggetto ma il contenuto dei messaggi
 La discussione non è dominata soltanto dai
soggetti più estroversi ma anche i più timidi
trovano uno spazio per esprimersi
 Passaggio dalla cultura dell’insegnamento a
quello dell’apprendimento: lo studente non è
più un oggetto dell’insegnamento ma diventa
il soggetto dell’apprendimento
Metodologie
d’apprendimento
Collaborativo
Personalizzato
 le attività cooperative
 la partecipazione degli
 possibilità di
studenti e degli
insegnanti
 le nuove conoscenze
emergenti da un
dialogo con scambio
di idee ed
informazioni
[Turoff, 1995]
scegliere il percorso
di studio più
congeniale alle sue
inclinazioni &
esigenze
 procede secondo
il proprio ritmo.
Pro e Contro
Pro
Contro
 Flessibilità di spazio
 Flessibilità di tempo
 Condivisione delle
 Difficoltà nell’uso delle
risorse
 Aumento dell’utenza
 Miglior gestione del
contenuto formativo
 Diminuzione dei costi
tecnologie informatiche
 Difficoltà nell’utilizzo
della scrittura per
comunicare
 Mancanza di segni di
comunicazione non
verbale
 Sovraccarico di
messaggi da leggere
Architettura del Sistema
MultiCom
 Client/Server
 TCP/IP
 Linguaggio di
programmazione:
Java
 Basi di dati:
MySql
 Materiale didattico:
formato
HTML/XML
Caratteristiche
 Multipiattaforma
 Base dati per gestione di informazioni e di materiale






didattico
Comunicazione client-server e server-base di dati:
protocollo XML
Serivizi di comunicazione:
 Sincroni: chat
 Asincroni: posta elettronica, Forum, Faq,bacheca
Interazione fra docenti, studenti ed amministrativi
Contenuti originali in Power Point 98, Word 98, html
Materiale didattico su server scaricabile in locale
Collegamenti ipertestuali fra corsi diversi
Innovazioni
 Java + MySql =
Sistema aperto multipiattaforma
 XML =
 per la comunicazione = indipendenza da
protocolli proprietari
 per il materiale didattico = gestione flessibile
dei documenti
Xml (eXtensible Markup Language
E’ un metalinguaggio che permette di creare
dei linguaggi personalizzati di markup
Per molte applicazioni e per
diversi settori, gli esperti
hanno già creato linguaggi di
markup specifici, come ad
esempio il Channel Definition
Format, il Mathematical
Markup Language ed altri, il
Learning Material Markup
Language.
CLIENT
Architettura
Modulo
Materiale
creazioneDidattico scaricato Dbms
materiale
(XML)
didattico
Browser
Client – MultiCom 2
Internet
Server
MultiCom 2
Materiale
didattico (XML)
Internet
Apache
Dbms
MultiCommunity
SERVER
Docenti
 Accesso alle informazioni generiche e/o a
quelle relative ai corsi
 Gestione del materiale didattico
 Suddivisione degli studenti in gruppi
 Amministrazione ed utilizzo di:
 Bacheche online, Faq, Newsgroup
 Messaggi, Chat
Studenti
 Iscrizione e richiesta dei corsi attivi
 Iscrizione ad un nuovo corso
 Accesso alle informazioni generiche e/o a quelle
relative ai corsi ed al materiale didattico
 Gestione del materiale didattico sul server *
 Suddivisione degli studenti in gruppi *
 Amministrazione * ed utilizzo di:
 Bacheche online, Faq, Newsgroup
 Messaggi, Chat
* su autorizzazione
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