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Personality Modelling
 

offline mohamed from the turtle business on 2010-01-27 06:09 [#02362318]
Points: 31145 Status: Regular | Show recordbag



'Everybody's talking about interactive storytelling these
days, but we've seen little real progress in the field. One
reason for this is the problem of creating good interactive
characters. Sure, there's a ton of non-interactive
characters out there, characters who really don't respond
well to the player. But genuinely interactive characters are
as common in our industry as humanoids in the Cretaceous
era.

The first step in building interactive characters is to
create a personality model. This is a set of attributes that
define the personality of the character. One might think of
the old attribute sets that one rolled up for characters in
fantasy role-playing games: traits such as Charisma,
Dexterity, Stamina, and so forth. But these traits don't
operate as a personality model. They don't tell you anything
about the personality of the character. All they tell you is
how the character performs certain tasks.

What we want are attributes that describe how the character
feels, how he reacts to the other characters. Where do we
get those?

Personality modelling is an old field in psychology. Before
psychology emerged as an academic field, there was
phrenology, which attempted to divine personality traits
from the bumps on one's head. Later on, there was a
simplistic model that recognized three poles, based on body
type, which in turn was based on which of the three basic
anatomical systems predominated during fetal development.
Persons whose digestive systems dominated became mesomorphs,
with round, flabby bodies. Those with pronounced
musculo-skeletal systems became endomorphs, with strong
athletic bodies; and those with exaggerated nervous systems
were ectomorphs, skinny wimps. A whole range of personality
traits were attributed to each of these somatypes. This
simplistic personality model has long since been utterly
discredited.

Over the years, personality models have come and gone with
dizzying speed. Jungians introduced multipolar diagrams,
Freudians had their own little systems, and the latest


 

offline mohamed from the turtle business on 2010-01-27 06:10 [#02362319]
Points: 31145 Status: Regular | Show recordbag



rage these days is a nine-pointed star. Along with this
we've gotten a whole vocabulary of personality typing. Are
you a Type A? Schizophrenic or even schizoid?
Obsessive-compulsive? Are you a Martian or a Venusian,
introverted or extroverted, task-oriented or
social-oriented, analytic or intuitive? Gack!

In truth, these are not personality models, they are
personality typing systems. They are coarse and primitive,
meant only to provide simple, rule-of-thumb appreciation of
human behavior. They are not used to define a personality,
only to give better understanding of behavior.

There has been more serious work among psychologists on the
problem of true personality modelling, but I must confess
that this work goes over my head. Moreover, these people are
trying to solve a problem we don't need to solve: they want
to model real human persoanlity; we need only model
characters. There's a big difference between real human
personality and a character the character is an idealized,
simplified representation of a real human being. A character
is to a real human being as a story is to life, or as a
portrait is to a photograph. A story is a simplification and
a clarification of life. It has a beginning, a middle, and
an end, where life just bounces along endlessly. A story has
a conflict and a resolution, where life has lots of boredom
and few resolutions to the conflicts that do arise. So our
task is not to create the perfect model of a real human
personality; instead, our task is to create a usable model
that permits us to create practical characters for
interactive stories.

Personality models are highly subjective. There is no such
thing as a "correct" personality model. This is all a black
art, and if you and I produce different personality models,
there is little basis for one to claim absolute superiority.
For this reason, I suspect that designing personality models
will be in the 90s what designing programming languages was
in the 70s. Everybody will do it, we'll have lots of
religious wars over whic


 

offline mohamed from the turtle business on 2010-01-27 06:10 [#02362320]
Points: 31145 Status: Regular | Show recordbag



h model is best, and nobody can know what the outcome will
be. Can you imagine the personality model analogues of FORTH
and APL?

However, just as with programming languages, there are some
rules of thumb that we can bring to bear on the design of
personality models.

A personality model will consist of a set of traits, or
variables. These are numbers that define the personality of
the character. One such trait might be gullibility, the
degree to which a character is willing to believe other
people's assertions.

At this point we run into a fundamental question: what kind
of number to we want to represent our character attributes?
This may seem like a strange question to the nonprogrammer,
but it can be very important. There are two basic
approaches: floating point values and integers.

The floating point value permits more accurate calculations.
When using a floating-point value, the character attribute
would be assigned a value between 0 and 1. Thus, a person
with gullibility of 1.0 is totally, completely gullible
("Golly gee, you'll really sell me the whole Brooklyn Bridge
for just $100? That's a real bargain!") whereas a person
with a gullibility of 0.0 believes nobody ("You think that
just because we're in the Vatican and you're wearing that
white robe and surrounded by all those guys in red, that I'm
gonna believe that you're really the Pope? I'm not that
dumb!")

However, floating point values take up lots of memory to
store (typically six bytes per value) and they take lots
more CPU time to process (typically 10 - 100 times as much
CPU time as integers). My experience has been that the RAM
costs of using floating point values for personality
attributes are not worth worrying about. However, the costs
in execution speed are, in my opinion, a significant factor.
My experience with a 40 MHz 68030 suggests that, even with
integer calculations, execution times for complex
interactive storytelling calculations are significant. With
floating point calculations, I believe that execution time


 

offline mohamed from the turtle business on 2010-01-27 06:11 [#02362321]
Points: 31145 Status: Regular | Show recordbag



s for complex interactive storytelling calculations are
significant. With floating point calculations, I believe
that execution times would impose a significant constraint
on the performance of the system as a whole. However, I have
not performed the detailed execution time analyses necessary
to assign great confidence to my hunch.

My own project uses integer values for personality
attributes. In this case, each attribute falls in the range
0 - 100. This allows me to multiply two of these integers
together and still remain in the safe zone for 16-bit
calculations. It would not be difficult to extend these
values to 32-bit longwords, with attribute ranges of 0 -
10,000. In fact I think that it would be advisable, because
I have encountered one class of calculation in which
roundoff error is a significant problem.

My overall conclusions as to word size are as follows: with
32-bit processors, the 16-bit integers offer few speed
advantages and some significant problems with roundoff
error. I suspect that 32-bit integers are the ideal word for
personality modelling with such processors. While I suspect
that 32-bit integers would offer overall better performance
than floating-point values, I would not take issue with a
designer who opted for the floating-point values.

The next big question concerns the type of attributes
permitted. There are three broad types of attributes:
one-dimensional, two-dimensional, and three-dimensional.

One-dimensional attributes are traits intrinsic to the
character alone, traits such as gullibility, greed, pride,
and so forth.

Two-dimensional attributes concern the character's
relationship with other characters, such as affection,
trust, or respect.

Three-dimensional attributes concern the character's
perception of other characters' relationships with each
other. Does Mary think that Joe loves his secretary? Does
John believe that Fred respects his boss? These are
important factors in the prosecution of gossip.

I have described these attributes as falling in a positi


 

offline mohamed from the turtle business on 2010-01-27 06:11 [#02362322]
Points: 31145 Status: Regular | Show recordbag



ve numeric range: 0 to 1 or 0 to 100. In practice, it's a
little more complicated. One-dimensional attributes are best
used in this positive range, but the two- and
three-dimensional attributes are more readily handled as
signed variables. Thus, gullibility is something that you
can have little of or lots of, but there's no such thing (in
my system) as "negative gullibility". On the other hand,
trust can definitely be negative. Zero trust is not as bad
as active distrust.

This distinction between unsigned variables and signed
variables is based on much experience with using personality
models. There are plenty of cases in which, in writing your
behavior equations, you want to take advantage of the sign
of the personality attribute. Suppose, for example, that Tom
observes Fred punching Joe, and we wish to calculate Tom's
reaction, which in turn depends heavily on Tom's affection
for Joe. If Tom likes Joe, then he'll be angry with Fred,
but if he hates Joe, then he might applaud Fred. Such a
reaction springs directly from the equations if we use
signed variables.

Now that we know the broad classes of attributes, it is
necessary to choose a set of likely attributes. What factors
inform our selection?

The first factor is our desire for completeness. We need a
set of attributes that cover the territory of our
characters' behavior. If, for example, our characters will
be wheeling and dealing, then gullibility had better be one
of the attributes in our personality model. On the other
hand, if this is a kiddie game, with no sexual behavior
considered, then we really don't need to keep track of each
character's lust value. In general, we want a broad set of
attributes that cover all the bases. The temptation then
becomes to pile on the attributes, to build a big model with
lots and lots of attributes, to be absolutely certain that
we've got everything covered. And why shouldn't we? Adding
another attribute costs perhaps two bytes per character. Big
deal pile 'em on, right?

Wrong. Designing a perso


 

offline mohamed from the turtle business on 2010-01-27 06:12 [#02362323]
Points: 31145 Status: Regular | Show recordbag



nality model is like designing a programming language. Every
beginning programmer at some time attempts to design his own
language, and the most common error in these cases is
"kitchen sink design". He throws in all sorts of obscure,
clever, picayune features that make perfect sense to the
designer and are utterly obscure to everybody else. A
programming language is meant to be used, and it is not
practical to learn a language that is cluttered with a large
set of special-case, narrow-application capabilities. In the
same way, a personality model needs parsimony. If you pile
on too many attributes, when it comes time to actually use
the model, you'll have a hell of time figuring out how to
apply the different attributes. Should Fred's reaction to
Tom's abusive words be based on Fred's respect for Tom, or
his dominance over him, or his fear for him, or his innate
submissiveness, or perhaps his affection for Tom would cause
him to overlook Tom's behavior, but then there's Fred's
pride to consider, and his natural volatility he might lose
his temper -- but his self-confidence could alleviate
that... Aargh!!! Too many variables make your design work
harder, not easier.

What you need is orthogonality, the mathematical notion of
independence. Two lines are orthogonal if they are at right
angles to each other; moving down one line yields no motion
in the direction of the other. If the two lines are at an
angle other than a right angle, then moving down one line
produces a partial displacement in the direction of the
other line. You want much the same thing with your
personality attributes. For example, respect and dominance
are not orthogonal; if I respect you then I probably accord
you some degree of dominance. On the other hand, lust and
gullibility are probably orthogonal; if I know that you are
gullible, that does not suggest how lusty you might be.

So we now have a means for establishing a good set of
personality attributes. We want the biggest, most complete
set of attributes whose members are ortho


 

offline mohamed from the turtle business on 2010-01-27 06:12 [#02362324]
Points: 31145 Status: Regular | Show recordbag



gonal. (For all you math types, all I'm saying is that we
want the set of orthogonal vectors that span the vector
space of desired character personality.)

The next concept I will advance is the notion of
correspondence between the different dimensions of
attributes. In other words, we want each one-dimensional
attribute to have a corresponding two-dimensional attribute
and a corresponding three-dimensional attribute. This may
sound abstruse, but it's really quite simple. Gullibility is
a one-dimensional attribute, a factor that is intrinsic to
the personality of the character. Trust is the
two-dimensional attribute analog of gullibility, and
perceived trust is the three-dimensional attribute.

To refine the point, let me observe that there should really
be two one-dimensional attributes for every two-dimensional
attribute. The first attribute is the proclivity to accord
the emotion in question to another person; the second
attribute is the character trait that causes other
characters to accord it to the character. In our example
involving trust, these two attributes would be gullibility
and honesty.

These are the basic principles you use in building a
personality model.

http://www.erasmatazz.com/library/JCGD_Volume_7/Personality
_Modelling.html


 

offline Barcode from United Kingdom on 2010-01-27 07:09 [#02362330]
Points: 1767 Status: Lurker



yawwwwwwnnnnn!


 

offline mohamed from the turtle business on 2010-01-27 07:10 [#02362332]
Points: 31145 Status: Regular | Show recordbag



:)


 

offline nightex from Šiauliai (Lithuania) on 2010-01-27 08:56 [#02362356]
Points: 1275 Status: Lurker



Personality cant be encoded, and studied with help of
integers, until we maybe found how AI works, and how we can
think in the way we do.

How can you study programs not knowing hardware (you need
develop drivers and BIOS programs in order to operate
programs and operating systems) Same is with human
personality, I think. This article mentions how difficult is
to know how persona will feel in certain situation, it is
because we cant really even grasp whats going on inside ones
brain (except maybe unverbal communication helps to guess
whats going on). Thats why approximation is only way how
those personality determination methods work.

My personal opinion is that intelligent people tend to swap
those personality types in order to achieve something or
simply to adapt in situation. In this sense there is
completely unpredictable people out there.


 

offline mohamed from the turtle business on 2010-01-27 09:51 [#02362369]
Points: 31145 Status: Regular | Followup to nightex: #02362356 | Show recordbag



language is the key to understand that communication sucks.
so does the lack of it, and thats the hole where the
unpredictabes poop in. i'm talking to a mirror 24/7, whether
biologically or internetly. now, if i had looking a glass,
would i find a use for it while breaking it? i wouldn't,
just becos i'm superstitious.


 

offline khrimson from the fridge on 2010-01-27 10:52 [#02362390]
Points: 1757 Status: Regular



tl dr;


 


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