Direct
manipulation
systems
offer
the
satisfying
experience
of
operating
on
visible
objects.
The
computer
becomes
transparent,
and
users
can
concentrate
on
their
tasks.
Direct
Manipulation:
A
Step
Beyond
Programming
Languages
Ben
Shneiderman,
University
of
Maryland
Leibniz
sought
to
make
the
form
of
a
symbol
reflect
its
content.
"In
signs,"
he
wrote,
"one
sees
an
adsantage
for
discovery
that
is
greatest
wshen
they
express
the
exact
nature
of
a
thinlg
briefly
and,
as
it
were,
picture
it;
then,
in-
deed,
the
labor
of
thought
is
sonderfully
diminished."
Frederick
Kreiling,
"Leibniz,"
Scientific
A
merican,
M
ay
1
968
Certain
interactive
systems
generate
glowing
en-
thusiasm
among
users-in
marked
contrast
with
the
more
common
reaction
of grudging
acceptance
or
out-
right
hostility.
The
enthusiastic
users'
reports
are
filled
with
positive
feelings
regarding
*
mastery
of
the
system,
*
competence
in
the
performance
of
their
task,
*
ease
in
learning
the
system
originally
and
in
assimi-
lating
advanced
features,
*
confidence
in
their
capacity
to
retain
mastery
over
time,
*
enjoyment
in
using
the
system,
*
eagerness
to
show
it
off
to
novices,
and
*
desire
to
explore
more
powerful
aspects
of
the
system.
These
feelings
are
not,
of
course,
universal,
but
the
amalgam
does
convey
an
image
of
the
truly
pleased
user.
As
I
talked
with
these
enthusiasts
and
examined
the
sys-
tems
they
used,
I
began
to
develop
a
model
of
the
fea-
tures
that
produced
such
delight.
The
central
ideas
seemed
to
be
visibility
of
the
object
of
interest;
rapid,
reversible,
incremental
actions;
and
replacement
of
com-
plex
command
language
syntax
by
direct
manipulation
of
the
object
of
interest-hence
the
term
"direct
manip-
ulation.
"
Examples
of
direct
manipulation
systems
No
single
system
has
all
the
attributes
or
design
fea-
tures
that
I
admire-that
may
be
impossible-but
those
described
below
have
enough
to
win
the
enthusiastic
sup-
port
of
many
users.
Display
editors.
"Once
you've
used
a
display
editor,
you'll
never
want
to
go
back
to
a
line
editor.
You'll
be
spoiled."
This
reaction
is
typical
of
those
who
use
full-
page
display
editors,
who
are
great
advocates
of
their
systems
over
line-oriented
text
editors.
I
heard
similar
comments
from
users
of
stand-alone
word
processors
such
as
the
Wang
system
and
from
users
of
display
editors
such
as
EMACS
on
the
MIT/Honeywell
Multics
system
or
"vi"
(for
visual
editor)
on
the
Unix
system.
A
beaming
advocate
called
EMACS
"the
one
true
editor."
Robertsl
found
that
the
overall
performance
time
of
display
editors
is
only
half
that
of
line-oriented
editors,
and
since
display
editors
also
reduce
training
time,
the
evidence
supports
the
enthusiasm
of
display
editor
devo-
tees.
Furthermore,
office
automation
evaluations
consis-
tently
favor
full-page
display
editors
for
secretarial
and
executive
use.
The
advantages
of
display
editors
include
Display
of
a
full
24
to
66
lines
of
text.
This
full
display
enables
viewing
each
sentence
in
context
and
simplifies
reading
and
scanning
the
document.
By
contrast,
the
A
portion
of
this
article
was
derived
from
the
author's
keynote
address
at
the
NYU
Symposium
on
User
Interfaces,
"The
Future
of
Interactive
Systems
and
the
Emergence
of
Direct
Manipulation,"
published
in
Human
Factors
in
Interactiue
Computer
Systems,
Y.
Vassiliou,
ed.,
Ablex
Publishing
Co.,
Norwood,
N.J.,
1983.
s
9162
83
08(
)-00'-15(I
-00
1i983
LEEF
57
August
1983
one-line-at-a-time
view
offered
by
line
editors
is
like
see-
ing
the
world
through
a
narrow
cardboard
tube.
Display
of
the
document
in
its
final
form.
Eliminat-
ing
the
clutter
of
formatting
commands
also
simplifies
reading
and
scanning
the
document.
Tables,
lists,
page
breaks,
skipped
lines,
section
headings,
centered
text,
and
figures
can
be viewed
in
the
form
that
will
be
printed.
The
annoyance
and
delay
of
debugging
the
format
com-
mands
is
eliminated
because
the
errors
are
immediately
apparent.
Cursor
action
that
is
visible
to
the
user.
Seeing
an
ar-
row,
underscore,
or
blinking
box
on
the
screen
gives
the
operator
a
clear
sense
of
where
to
focus
attention
and
ap-
ply
action.
Cursor
motion
through
physically
obvious
and
intui-
tively
natural
means.
Arrow
keys
or
devices
such
as
a
mouse,
joystick,
or
graphics
tablet
provide
natural
physical
mechanisms
for
moving
the
cursor.
This
is
in
marked
contrast
with
commands
such
as
UP
6,
which
re-
quire
an
operator
to
convert
the
physical
action
into
cor-
rect
syntactic
form
and
which
may
be
difficult
to
learn,
hard
to
recall,
and
a
source
of
frustrating
errors.
Labeled
buttons
for
action.
Many
display
editors
have
buttons
etched
with
commands
such
as
INSERT,
DELETE,
CENTER,
UNDERLINE,
SUPERSCRIPT,
BOLD,
or
LOCATE.
They
act
as
a
permanent
mehu
se-
lection
display,
reminding
the
operator
of
the
features
and
obviating
memorization
of
a
complex
command-lan-
EDIT
---
SPFDEMO.MYLIB.PLI(COINS)
-
01.04
-------------------
COLUMNS
001
072
COMMAND
INPUT
=>
SCROLL
===>
HALF
*X****
*********************~******
TOP
OF
DATA
*
000100
COINS:
000Z00
PROCEDURE
OPTIONS
(MAIN);
000*300
DECLARE
000400
CCUNT
FIXED
BINARY
(31)
AUTOMATIC
INIT
(1),
000500
HALVES
FIXED
BINARY
(31),
000600
QUARTERS
FIXED
BINARY
(31),
000700
DIMES
FIXED
BINARY
(31),
I3
NICKELS
FIXED
BINARY
(31),
000900
SYSPRINT
FILE
STREAM
OUTPUT
PRINT;
001000
DO
HALVES
=
100
TO
0
BY
-50;
001100
DO
QUARTERS
=
(100
-
HALVES)
TO
0
BY
-25;
001200
DO
DIMES
=
((100
-
HALVES
-
QUARTERS)/10)*10
TO
0
BY
-10;
001300
NICKELS
=
100
-
HALVES
-
QUARTERS
-
DIMES;
D
PUT
FILE(SYSPRINT)
DATA(COUNT,HALVES,QUARTERS,DIMES,NICKELS);
001500
COUNT
=
COUNT
+
1;
001600
END;
001700
END;
001800
END;
001900
END
COINS;
******
BOTTOM
OF
DATA
******
********
*
EDIT
---
SPFDEMO.MYLIB.PLI(COINS)
-
01.04
-------------------
COLUMNS
001
072
COMMAND
INPUT
=
SCROLL
=
HALF
*****
*****************
**********
TOP
OF
DATA
*****
**************
000100
COItS:
000200
PROCEDURE
OPTIONS
(MAIN);
000300
DECLARE
000400
COUNT
FIXED
BINARY
(31)
AUTOMATIC
INIT
(1),
000500
HALVES
FIXED
BINARY
(31),
000600
QUARTERS
FIXED
BINARY
(31),
000700
DIMES
FIXED
BINARY
(31),
000800
NICKELS
FIXED
BINARY
(31),
000900
SYSPRINT
FILE
STREAM
OUTPUT
PRINT;
001000
DO
HALVES
100
TO
0
BY
-50;
001100
DO
QUARTERS
=
(100
-
HALVES)
TO
0
BY
-25;
001^00
DO
DIMES
((100
-
HALVES
-
QUARTERS)/10)*10
TO
0
BY
-10;
001300
NICKELS
=
100
-
HALVES
-
QUARTERS
-
DIMES;
001500
COUNT
=
COUNT
4
1;
001600
END;
001700
END;
001800
END;
001C00
END
COINS;
******
***************************
BOTTOM
OF
DATA
***
*******
*****
58
COMPUTER
guage
syntax.
Some
editors
provide
basic
functionality
with
only
10
or
15
labeled
buttons,
and
a
specially
marked
button
may
be
the
gateway
to
advanced
or
infre-
quently
used
features
offered
on
the
screen
in
menu
form.
Immediate
display
of
the
results
of
an
action.
When
a
button
is
pressed
to
move
the
cursor
or
center
the
text,
the
results
appear
on
the
screen
immediately.
Deletions
are
apparent
at
once,
since
the
character,
word,
or
line
is
erased
and
the
remaining
text
rearranged.
Similarly,
in-
sertions
or
text
movements
are
shown
after
each
key-
stroke
or
function
button
press.
Line
editors,
on
the
other
hand,
require
a
print
or
display
command
before
the
results
of
a
change
can
be
seen.
Rapid
action
and
display.
Most
display
editors
are
designed
to
operate
at
high
speeds:
120
characters
per
second
(1200
baud),
a
full
page
in
a
second
(9600
baud),
or
even
faster.
This
high
display
rate
coupled
with
short
response
time
produces
a
thrilling
sense
of
power
and
speed.
Cursors
can
be
moved
quickly,
large
amounts
of
text
can
be
scanned
rapidly,
and
the
results
of
commands
can
be
shown
almost
instantaneously.
Rapid
action
also
reduces
the
need
for
additional
commands,
thereby
sim-
plifying
product
design
and
decreasing
learning
time.
Line
editors
operating
at
30
characters
per
second
with
three-
to
eight-second
response
times
seem
sluggish
in
comparison.
Speeding
up
line
editors
adds
to
their
attrac-
tiveness,
but
they
still
lack
features
such
as
direct
over-
typing,
deletion,
and
insertion.
Easily
reversible
commands.
Mistakes
in
entering
text
can
be
easily
corrected
by
backspacing
and
overstriking.
Simple
changes
can
be
made
by
moving
the
cursor
to
the
problem
area
and
overstriking,
inserting,
or
deleting
characters,
words,
or
lines.
A
useful
design
strategy
is
to
include
natural
inverse
operations
for
each
operation.
Carroll2
has
shown
that
congruent
pairs
of
operations
are
easy
to
learn.
As
an
alternative,
many
display
editors
offer
a
simple
UNDO
command
that
cancels
the
previous
command
or
command
sequence
and
returns
the
text
to
its
previous
state.
This
easy
reversibility
reduces
user
anx-
iety
about
making
mistakes
or
destroying
a
file.
The
large
market
for
display
editors
generates
active
competition,
which
accelerates
evolutionary
design
re-
finements.
Figure
I
illustrates
the
current
capabilities
of
an
IBM
display
editor.
Visicaic.
Visicorp's
innovative
financial
forecasting
program,
called
Visicalc,
was
the
product
of
a
Harvard
MBA
student,
who
was
frustrated
by
the
time
needed
to
carry
out
multiple
calculations
in
a
graduate
business
course.
Described
as
an
"instantly
calculating
electronic
worksheet"
in
the
user's
manual,
it
permits
computation
and
display
of
results
across
254
rows
and
63
columns
and
is
programmed
without
a
traditional
procedural
con-
trol
structure.
For
example,
positional
declarations
can
prescribe
that
column
4
displays
the
sum
of
columns
I
through
3;
then
every
time
a
value
in
the
first
three
col-
umns
changes,
the
fourth
column
changes
as
well.
Com-
plex
dependencies
among
manufacturing
costs,
distribu-
tion
costs,
sales
revenue,
commissions,
and
profits
can
be
stored
for
several
sales
districts
and
months
so
that
the
impact
of
changes
on
profits
is
immediately
apparent.
Since
Visicalc
simulates
an
accountant's
worksheet,
it
is
easy
for
novices
to
comprehend.
The
display
of
20
rows
and
up
to
nine
columns,
with
the
provision
for
multiple
windows,
gives
the
user
sufficient
visibility
to
easily
scan
information
and
explore
relationships
among
entries
(see
Figure
2).
The
command
language
for
setting
up
the
worksheet
can
be
tricky
for
novices
to
learn
and
for
infre-
quent
users
to
remember,
but
most
users
need
learn
only
the
basic
commands.
According
to
Visicalc's
distributor,
"It
jumps,"
and
the
user's
delight
in
watching
this
prop-
agation
of
changes
cross
the
screen
helps
explain
its
appeal.
Figure
2.
This
simple
Visicalc
program
display
(top)
shows
four
col-
umns
and
20
rows
of
home
budget
information.
The
cursor,
an
inverse
video
light
bar
controlled
by
key
presses,
is
in
position
C2.
The
top
command
line
shows
that
C2
is
a
value
(as
opposed
to
a
text
string)
that
has
been
set
up
to
have
the
same
value
as
position
B2.
The
second
display
(above)
shows
two
windows
over
the
home
budget
data
with
row
sums
to
the
right.
The
last
row
shows
leisure
dollar
amounts,
which
are
established
by
the
top
command
line
formula
as
the
income
minus
the
sum
of
expenses.
A
change
to
the
income
or
ex-
pense
values
would
immediately
propagate
to
all
affected
values.
(Displays
reproduced
by
permission
of
Visicorp.)
59
August
1983
Spatial
data
management.
The
developers
of
the
pro-
totype
spatial
data
management
system3
attribute
the
basic
idea
to
Nicholas
Negroponte
of
MIT.
In
one
scenario,
a
user
seated
before
a
color
graphics
display
of
the
world
zooms
in
on
the
Pacific
to
see
markers
for
military
ship
convoys.
Moving
a
joystick
fills
the
screen
with
silhouettes
of
individual
ships,
which
can
be
zoomed
in
on
to
display
structural
details
or,
ultimate-
ly,
a
full-color
picture
of
the
captain.
(See
Figure
3.)
In
another
scenario,
icons
representing
different
aspects
of
a
corporation,
such
as
personnel,
organiza-
tion,
travel,
production,
or
schedules,
are
shown
on
a
screen.
Moving
the
joystick
and
zooming
in
on
objects
takes
users
through
complex
"information
spaces"
or
"I-spaces"
to
locate
the
item
of
interest.
For
example,
when
they
select
a
department
from
a
building
floor
Figure
3.
A
spatial
data
management
system
has
been
in-
stalled
on
the
aircraft
carrier
USS
Carl
Vinson.
In
the
photo
at
top
left,
the
operator
has
a
world
map
on
the
left
screen
and
a
videodisc
map
of
selected
areas
on
the
center
screen.
After
some
command
selections
with
the
data
tablet
and
puck,
the
operator
can
zoom
in
on
specif-
ic
data
such
as
the
set
of
ships
shown
in
the
second
photo.
With
further
selections
the
operator
can
get
de-
tailed
information
about
each
ship,
such
as
the
length,
speed,
and
fuel.
(Photos
courtesy
of
Computer
Corporation
of
America.)
In
1971,
about
the
only
people
playing
video
games
were
students
in
computer
science
laboratories.
By
1973,
however,
millions
of
people
were
familiar
with
at
least
one
video
game-Pong
(above
left).
A
few
years
later
came
Breakout
(above
right),
which,
according
to
many
designers
was
the
first
true
video
game
and
the
best
one
ever
invented.
Pong
and
other
early
games
imitated
real
life,
but
Breakout
could
not
have
existed
in
any
medium
other
than
video.
In
the
game,
a
single
paddle
directed
a
ball
toward
a
wall
of
color
bricks;
contact
made
a
brick
vanish
and
changed
the
ball's
speed.
When
the
first
arcade
video
game,
Computer
Space,
went
on
location
in
a
Sears
store,
its
joystick
was
torn
of
f
before
the
end
of
the
first
day.
As
a
result,
game
designers
have
sought
controls
that
were
both
easy
to
use
and
hard
to
destroy.
Centipede
(above
left)
uses
simple
controls-a
trackball
and
one
button.
On
the
other
hand,
Defender
(above
right)
has
fIve
buttons
and
a
joystick;
novice
players
are
confused
by
these
relatively
complex
controls
and
usually
give
up
after
a
few
seconds.
COMPUTER
60
plan,
individual
offices
become
visible.
Moving
the
cur-
sor
into
a
room
brings
the
room's
details
onto
the
screen.
If
they
choose
the
wrong
room,
they
merely
back
out
and
try
another.
The
lost
effort
is
minimal,
and
no
stigma
is
attached
to
the
error.
The
success
of
a
spatial
data
management
system
de-
pends
on
the
designer's
skill
in
choosing
icons,
graphical
representations,
and
data
layouts
that
are
natural
and
easily
understood.
Even
anxious
users
enjoy
zooming
in
and
out
or
gliding
over
data
with
a
joystick,
and
they
quickly
demand
additional
power
and
data.
Video
games.
Perhaps
the
most
exciting,
well-engi-
neered-certainly,
the
most
successful-application
of
direct
manipulation
is
in
the
world
of
video
games.
An
early,
but
simple
and
popular,
game
called
Pong
re-
quired
the
user
to
rotate
a
knob,
which
moved
a
white
rectangle
on
the
screen.
A
white
spot
acted
as
a
Ping-
Pong
ball,
which
ricocheted
off
the
wall
and
had
to
be
hit
back
by
the
movable
white
rectangle.
The
user
developed
skill
involving
speed
and
accuracy
in
placement
of
the
"paddle"
to
keep
the
increasingly
speedy
ball
from
get-
ting
by,
while
the
speaker
emitted
a
ponging
sound
when
the
ball
bounced.
Watching
someone
else
play
for
30
seconds
was
all
the
training
needed
to
become
a
compe-
tent
novice,
but
many
hours
of
practice
were
required
to
become
a
skilled
expert.
Contemporary
games
such
as
Missile
Command,
Don-
key
Kong,
Pac
Man,
Tempest,
Tron,
Centipede,
or
Space
Invaders
are
far
more
sophisticated
in
their
rules,
color
graphics,
and
sound
effects
(see
sidebar
below
and
on
facing
page).
The
designers
of
these
games
have
pro-
vided
stimulating
entertainment,
a
challenge
for
novices
and
experts,
and
many
intriguing
lessons
in
the
human
factors
of
interface
design-somehow
they
have
found
a
way
to
get
people
to
put
coins
into
the
sides
of
com-
puters.
The
strong
attraction
of
these
games
contrasts
markedly
with
the
anxiety
and
resistance
many
users
ex-
perience
toward
office
automation
equipment.
Because
their
fields
of
action
are
abstractions
of
reali-
ty,
these
games
are
easily
understood-learning
is
by
analogy.
A
general
idea
of
the
game
can
be
gained
by
watching
the
on-line
automatic
demonstration
that
runs
continuously
on
the
screen,
and
the
basic
principles
can
be
learned
in
a
few
minutes
by
watching
a
knowledgeable
player.
But
there
are
ample
complexities
to
entice
many
hours
and
quarters
from
experts.
The
range
of
skill
ac-
commodated
is
admirable.
The
commands
are
physical
actions,
such
as
button
presses,
joystick
motions,
or
knob
rotations,
whose
results
appear
immediately
on
the
screen.
Since
there
is
no
syntax,
there
are
no
syntax
error
messages.
If
users
move
their
spaceships
too
far
left,
then
they
merely
use
the
natural
inverse
operation
of
moving
back
to
the
right.
Error
messages
are
unnecessary
because
the
results
of
ac-