the Shape of Things to Come: A Comparison of Direct Manipulation and
Interactive Evolutionary Design
Interactive Institute, Tools for Creativity and
Department of Informatics, Umeå University.
This paper is
concerned with differences between direct manipulation and interactive
evolutionary design as two fundamentally different interaction styles for
creative tasks. In order to empirically compare the two interaction styles, two
prototypes for typeface design were designed and implemented. An experimental
evaluation was carried out involving both prototypes and two different kinds of
task, one where the goal was clearly defined and one where the subjects had to
formulate the goal themselves. An analysis of the results suggests that
participants of the experiment experienced the direct manipulation prototype to
offer a higher degree of ability to affect the design of typefaces, compared to
interactive evolutionary design. Subjects also experienced themselves to be
more active while using the direct manipulation interface. The interactive
evolutionary design prototype was reported to being most suited for creative
tasks, while the direct manipulation prototype was experienced to be more
suitable for tasks where the goal is clearly defined.
degree, different artifacts may be described in terms of themes and variations
on themes. The figure below shows the letter ‘A’ in four different typefaces,
each one unique in its own right. Still, each typeface has a lot of features in
common that make them similar in many respects. Put differently, the typefaces
may be understood as different variations on the same theme.
notions of theme and variation on theme, design may – partly – be conceived as
an activity that includes exploration of a theme in search for pleasing
variations. In this example and in this paper, the object of design is
typefaces but could be something else, sunglasses, china, human-computer
interfaces or other kinds of objects. On a concrete level, the form of an
artifact may be described in terms of its absolute characteristics. For
instance, a specific variation on a typeface theme may have a certain weight,
width and other measures that define the exact form of the letters. On an
abstract level, the form may be described in terms of potential
characteristics, that is, a description that allows for a multitude of concrete
variations, each with its own unique form and qualities. Thus, an abstract
description of an artifact is rather a description of a design space, a set of
potential artifacts, a set of potential variations on a theme.
suggested by Ben Shneiderman , a challenge for designers of user interfaces
and human-computer interaction researchers is to design and develop information
technology that supports creativity. This paper reports on a project where I
have tried to take on that challenge. The project aims at comparing different interaction
styles that can be used to support creative exploration of design spaces. In
this paper, I am concerned with two fundamentally different ways of
interactively exploring a typeface design space: direct manipulation and
interactive evolutionary design. However, it is not the typographical aspects
of this design space that are at the center of this paper. Rather, my main
interest is the knowledge and understanding of users’ experiences from using
different modes of interaction in the exploration of design spaces. More
specifically, I am interested in (1) how users experience their ability to
affect the object of design while using the different interaction styles, (2)
the level of experienced activity, (3) whether they had fun using the
prototypes and (4) if users think that one interaction style is more
appropriate than the other for a specific kind of task.
The outline of
the paper is as follows. First, I present what I take to be important aspects
of the two interaction styles discussed in this paper: direct manipulation and
interactive evolutionary design. Second, the design of two software prototypes
is presented followed by a presentation of an experimental evaluation that was
conducted as part of the project. Finally, the results of the evaluation are.
manipulation interfaces, a term coined by Ben Shneiderman  in the
mid-seventies, are the kind of interface that is characteristic of most modern
personal computer application user interfaces. Typically, direct manipulation
interfaces incorporate a model of a context (such as a desktop environment)
supposedly familiar to users. Rather than giving textual commands (i.e.
"remove file.txt", "copy file1.txt file2.txt") to an
imagined intermediary between the user and the computer, the user acts directly
on the objects of interest to complete a task. More precisely, crucial features
of direct manipulation interfaces include  continuous and perceivable
representations of the objects of interest, physical actions instead of
complicated syntax and incremental actions that are rapid and reversible.
direct manipulation has played an important role in making computers accessible
to non-computer experts. Less certain are the reasons why direct manipulation
interfaces are so successful. It has been suggested  that this kind of
interaction style caters for a sense of directness, control and engagement in
the interaction with the computer. The possibilities of incremental action with
continuous feedback are believed to be an important factor of the
attractiveness of direct manipulation. Not least importantly, interaction with
direct manipulation systems is often experienced as enjoyable . However,
direct manipulation is also associated with some problems that make it a less
than ideal interaction style in some situations. Recently new interaction
styles have emerged that address the shortcomings of direct manipulation in
various ways. One example are so-called software agents  that, quite the
contrary to direct manipulation, act on behalf of the user and alleviate the
user from some of the attention and cognitive load traditionally involved in
the interaction with large quantities of information. However, this relief
comes at the cost of lost user control and requires the user to put trust into
a pseudo-autonomous piece of software.
style of human-computer interaction of special interest for creative tasks is
that of interactive evolutionary design (sometimes referred to as aesthetic
selection). Interactive evolutionary design is inspired by notions from
Darwinian evolution and may be described as a way of exploring a large –
potentially infinite – space of possible design configurations based on the
judgment of the user. This approach hereafter referred to as interactive
evolutionary design, typically involves the use of genetic algorithms  in combination with a human evaluator.
Rather than, as
is the case with direct manipulation, directly influencing the features of an
object, the user influences the design by means of expressing her judgment of
design examples. Each design example can be thought of as consisting of two
different representations, a genotype
and a phenotype. The phenotypical
representation is a concrete and perceivable rendition of an object that the
user evaluates. The genotypical representation is an encoded description of the
traits that a specific object in the design space has. The genotypical
representation can be implemented in many different ways, but the simplest kind
is a string of binary digits with fixed length. Examples judged positively by
the users are given an increased possibility of being selected by the genetic
algorithm to carry their traits to a new generation of design examples by means
of a reproduction process. The
reproduction process typically involves some form of crossover, that is, the
offspring’s traits are a combination of traits from the parents. The offspring
may also be subject to mutation in order to add an amount of random change to
the offspring. The offspring that constitute the new generation is, like the
first generation, subject to the scrutiny of the user. In an iterative fashion,
new examples are produced based on the selections made by the user and – hopefully
– each new generation contains examples that converge towards configurations
that are well adapted to the preferences of the user.
interactive evolutionary design have been employed to support design and creation
of a variety of objects. For instance, Karl Sims  has applied interactive
evolutionary techniques to evolve artistic 2D images and 3D plant structures.
Another well know example of artistic work is that of Todd and Latham  who
developed Mutator, a program that
supports exploration of 3D form. An interesting, non-artistic application of
interactive evolutionary design is the work by Gatarski  who applied
interactive evolution to design web-advertising banners. Much related to this
paper is the parametric font definition that allows for breeding of typefaces,
by Ian Butterfield and Matthew Lewis . Matthew Lewis maintains a web site
 with links to papers and other resources related to interactive
evolutionary design. Peter J. Bentley’s book Evolutionary Design  gives an
excellent overview of evolutionary approaches to design, both interactive and
difference between direct manipulation and interactive evolutionary design is
that direct manipulation seems to imply an ideology that a user should at all
times be in control of what is going on at the user interface. Interactive
evolutionary design may be understood as an approach where the user may expect
the unexpected, at the cost of giving up some amount of control. In the context
of creative tasks, this aspect may add an important dimension to human-computer
interaction that direct manipulation cannot provide. It seems plausible that
many people do not generally exhibit the skills, training and experience or do
not have the time required for advanced design work. In this respect,
interactive evolutionary design is very promising considering that most people
are competent at expressing likes and dislikes about their physical and social
environments, that is, they have a skill for judgment. Interactive evolutionary
design may be understood as a way to capitalize on that competence to make
design processes accessible a wider audience.
In the following
three subsections the prototypes used in the experiment is presented.
4.1 A Typeface design space
The design of
the two prototypes have been guided by the principle that they should be as
similar as possible to each other in all respects, except those features that
concern the style of interaction. One important common feature of the
prototypes is the notion of a typeface design space, that is, the space of
possible typefaces that can be explored by the prototypes. The design space is
organized by a number of parameters (seven in the current implementation) and
constitutes an abstract parameterized typeface. The parameterized typeface
includes a description of the shape of each glyph. However, these descriptions
are not formulated in terms of absolute values, but in terms of parameters.
Thus, the design of a specific typeface in the design space may be conceived of
as a kind collaborative design with contributions from both the designer of the
abstract parameterized typeface and from the user/designer that decides on the
values for the parameters.
The design of
each glyph in this typeface is partly governed by one or more of the seven
parameters. The overall design is deliberately made in a way that makes it
possible to have relatively few parameters with application to as many glyphs
as possible. In other words, I have tried to avoid a design space where a
parameter is of relevance only to one or very few glyphs. Rather, a change of
one parameter should propagate through out the whole typeface.
In the table
below the effect of the different parameters is illustrated.
Vertical bar width
Horizontal bar width
Lower case horizontal
Lower case vertical
The idea of a parametric
typeface is by no means new. A well-known example is Donald E. Knuth’s meta-font. A meta-font is, as defined by
Knuth, a “schematic description of how to draw a family of fonts” . Such a
description does not define one single font but rather a set of potential
fonts. Another example of parametric fonts is the multiple masters font technology from Adobe, Inc (see for instance
). A multiple master font is parametric in the sense that it includes two
or more glyph outlines. These outlines confine a design space of potential
fonts that are realized by means of interpolation between the included
In this paper
the parametric fonts themselves are not the core issue. However, they are an
interesting domain of design that gives rise to challenges concerning the tools
and methods for exploring very large design spaces. Knuth expresses the
richness of parametric designs in the following way [6, p. 292]:
So many variations are possible, in fact, that the
author keeps finding new settings of the parameters that give surprisingly
attractive effects not anticipated in the original design; the parameters that
give the most readability and visual appeal may never be found since there are
infinitely many possibilities.
concerns parametric typefaces, but could most likely be extrapolated to account
for exploration of parametric design spaces in general and motivates efforts
aiming at investigating how to better support and understand design space
exploration. In the following sections I will present the design of two
prototypes that each embodies a distinct style of supporting interactive
exploration of such spaces.
4.2 Direct manipulation prototype
As is the case
for both prototypes, the intention has been to keep the design as clean as possible
and to include only that which is essential for each interaction style. Below
is an image of the version of the direct manipulation prototype that was used
in the experimental evaluation.
As seen in the
picture, the user interface contains only two kinds of elements: a typeface
display and a number of sliders. Each slider corresponds to one of the seven
design space parameters described in the previous section. A user of this
prototype can navigate through the typeface design space by dragging the slider
handles to the right and left. As the user drags a slider, the visual display
is continuously updated.
Other version of
this prototype contains some features that are left out in the version
described here. For instance, the possibility to save the typeface as an
encapsulated postscript (eps) is not included. Also left out from this version,
are slider labels with the name of the different parameters. The labels were
considered to be included, but I decided to leave them out under the assumption
that the meaning of the textual labels could just as well be inferred the
feedback of slider movement. However, the soundness of this decision is by no
means obvious and could very well motivate an experiment on its own.
4.3 Interactive evolutionary design prototype
evolutionary design prototype has exactly the same design space as the direct
manipulation prototype, but offers a very different way of exploring that
space. The image below shows a screen shot of the user interface.
The list on the
left side of the window contains typeface examples generated by the program. In
the version used in the evaluation, the list always contained fifty examples.
This set of typefaces constitutes a generation. On a monitor with a resolution
of 1024x768, five typeface examples at a time are visible in the list. The user
selects typefaces that she or he in some way finds attractive – aesthetically
or otherwise – by double-clicking a typeface in the list of generated
typefaces. As soon as the user has selected a typeface, a copy of it appears in
the list on the right side of the window. The selected typeface is not removed
from the list to the left. Thus, a single typeface may be selected several
times. Below the two lists there is a button labeled “Nya exempel” (Swedish for
“New examples”). By clicking the button, the right list is cleared and a new
set of fifty examples appears in the left list. In this context, it may be
necessary to briefly go into some of details of the inner workings of the prototype.
visible in the interface may be considered as phenotypical representations of typefaces. Each typeface also has a
genotypical representation, that is,
an encoded specification of the typeface. Conceptually, the genotypical
representation of a typeface consists of a chromosome containing seven genes,
one for each design space parameter. Each gene is represented by a string of
binary digits. A chromosome can be thought of as something that identifies an
exact location in the design space, an exact description of a typeface. In
order to produce a new generation of typefaces, the genetic algorithm assigns a
probability to each typeface selected by the user so that they have equal
chance to become parents in a reproduction. The reproduction always involves
two parents and always results in two offspring. The genetic operators involved
in the reproduction of typefaces are mutation and crossover. In the particular
version of the prototype used in the evaluation, the probability for crossover and
mutation to occur is fixed and set to 0.08 and 0.7, respectively. Another
version of the prototype includes slider controls to adjust probabilities for
mutation and crossover.
In the design of
the experiment it was considered important to allow each subject to work with
both of the two prototypes and with different kinds of tasks. Two accomplish
this the experiment involved two kinds of tasks. In one kind of task – referred
to as the “copy task” – each subject were asked to copy or recreate a typeface
as displayed on a card presented to him or her during the experiment. The
displayed typefaces were generated from the same design space as the subjects
explored in the experiment. All the subjects performed this task with both. The
purpose of this task was to mimic a situation where the goal is explicit and
clearly defined. The second kind of task – referred to as the “creative task” –
required more creativity on part of the experiment participant as this task did
not involve recreating what some else had already designed. In this kind of
task, subjects were asked to design a textual logotype for a company. In the
fictitious scenarios presented to the participants the logotype should appear
on the products and in marketing material of by the company. The purpose of
this kind of task was to trigger a creative process to be able to assess how
the different prototypes supported that process.
involved 16 subjects, eight women and eight men. Each subject used both
prototypes and performed both kinds of tasks with each prototype. The duration
of a typical experiment session was on average 30 minutes. During each session,
subjects were asked to think aloud to give a verbal account of their
interaction with the prototype. These verbal accounts were recorded and
transcribed afterwards. The subjects were also asked to answer ten questions in
6.1 Experienced ability to affect design
earlier in this paper, direct manipulation is known to cater for a strong sense
of directness and control, leaving the user in charge of the object of
manipulation. Intuitively, interactive evolutionary design seems to be a more
indirect way of interacting with computers. Two questions in the questionnaire
concerned the degree to which the users experienced that they could affect the
design of typefaces using the two different prototypes:
To what degree do you experience that you can affect the design of the
typefaces using tool A (direct manipulation)
Q2: To what degree do you experience that you can affect the design of the typefaces using tool B (interactive evolutionary design)
analyzing the results of these two questions I suspected that the users taking
part in the evaluation would report that they experienced the direct
manipulation prototype to offer a higher degree of ability to affect the design
of typefaces, compared to interactive evolutionary design. Just by looking at
the scale and the different means in the table of descriptive statistics below
seem to confirm that intuition.
In order to
establish if this difference is a statistically significant difference, a
paired t-test was carried out:
It turns out
that the difference is very highly significant which more than well confirms
the initial assumption about how the subjects would experience the different
tools’ ability to cater for a sense of being able to affect the design of the
6.2 Experienced level of activity
manipulation is – almost by definition
– a very active mode of interaction. Indeed, the requirement to be
active in order for the computer to be reactive is something that sometimes
motivates alternative interaction styles, such as software agents. My initial
intuitions about interactive evolutionary design were that it would be
experienced as a comparatively passive mode of interaction in the context of
typeface design. The users were given the following two questions:
Q3: Were you active or passive
while using tool B (interactive evolutionary design)?
Q4: Were you active or passive while using tool A (direct manipulation)?
As shown on the
scale and in the table below, the mean for the level of experienced activity
using the direct manipulation interface is very high (and with a fairly low
standard deviation). This may not be very surprising. However, I would have
expected that the mean for the interactive evolutionary design interface to be
somewhat lower than reported.
A t-test reveals
that the difference of experienced activity is significant, although not to a
very great extent (p < 0.05).
It should be
mentioned that some subjects asked me about how to interpret these two
questions. On a more speculative basis, the problems of interpreting the
questions may indicate that both direct manipulation and interactive
evolutionary design involve a rather high level of activity, but different in
character. While the activity in direct manipulation typically involves the
manipulation of one single object at a time, interactive evolution involves an
active selection from a potentially large set of objects.
6.3 Experienced level of amusement
In the section
about direct manipulation in the beginning of this paper, it is observed that
direct manipulation typically is associated with a high degree of subjective
satisfaction, that is, people tend to find it pleasurable to work with direct
manipulation interfaces. I am interested in whether there are differences
between direct manipulation interfaces and interactive evolutionary design
concerning this aspect of human-computer interaction. In order to investigate
if subjects were bored or amused using the two different prototypes the
questionnaire contained the following questions:
Q5: Was it fun to use tool A?
Q6: Was it fun to use tool B? (interactive evolutionary design)
By looking at
the means of the ratings made by the subjects it seems as if both prototypes
were experienced as being fun to use.
As shown on the
scale, it appears as if the mean for the direct manipulation prototype is
slightly higher than the mean for interactive evolutionary design. However, a
t-test reveals that this difference is not statistically significant (p >
As a note of caution, it is not obvious that
what is being experienced to be fun in the evaluation are tools or interactions
styles themselves. It may very well be the case that the task domain, typeface
design, is the source of amusement.
6.4 Experienced predictability of decisions and actions
The some extent, the intelligibility of
interaction styles and user interfaces is determined by the degree to which
users experience some amount of rationality concerning the relation between
their actions and the computer’s response to the actions. In the questionnaire,
I tried to approach this issue by asking whether the subjects considered the
consequences of their actions and decisions to be predictable for the different
Q9: How would you describe the
consequences of your decisions and actions using tool A? (direct manipulation)
Q10: How would you describe the consequences of your decisions and actions using tool B? (interactive evolutionary design)
If we look at
the scale it appears at first sight as if the consequences of users’ decisions
and actions are experienced to be more predictable when using the direct
manipulation interface prototype. This may not be very surprising since one of
the cornerstones of direct manipulation is small, incremental action with
continuous feedback that allows the user to see what is happening as a result
of her actions.
However, if we look at the standard deviations
for the two means they are fairly high and a t-test reveals that we cannot
conclude – with statistical significance – that there is a difference between
the two means (p>0.05). Thus, based on the data from this evaluation, the
two prototypes are experienced to be equally predictable.
6.5 For what kind of task are the different tools most suited?
before, each subject used both prototypes for solving two different kinds of
task. The questionnaire included two questions to capture if the subjects
experienced one kind of tool as more apt for one kind of task. The questions
were formulated as:
Q7: For what kind of task is
tool A (direct manipulation) most suited?
Q8: For what kind of task is tool B (interactive evolutionary design) most suited?
As in all other
eight questions, the answer took the form as a marking on a continuous scale.
The extremes on the scales were “Definitely type 1” and “Definitely type 2”. Type 1 referred to the
kind of task where the user was supposed to recreate a pre-designed typeface as
displayed on a card. Type 2 referred to the kind of task where the user had to
formulate the goal on her own based on a short scenario.
In the analysis,
the answer markings on the scales were re-interpreted as signifying that a
specific tool – A or B – were experienced as being suited for either type 1
tasks or type 2 tasks. It was decided that markings on the exact middle of the
scales should be left out of the data set. However, this was never the case.
The coding resulted in a frequency table:
If we look at this
table, it appears as if the direct manipulation prototype was experienced by
the subjects to be more suited for the kind of task where the goal is clearly
defined and explicit, whereas the interactive evolutionary design prototype
seems to be experienced as more suited for the more creative, scenario-based
kind of task.
To test whether
the frequency distribution among the cells in the table really is not just
coincidental a chi square test was employed:
The chi square test
tells us that the difference in frequency distribution among the cells is very
highly significant. Thus, it seems as if there is a real difference concerning
the way that subjects experienced the suitability of the different prototypes.
6.6 Some observations from verbal accounts
Only so much can
be captured in a questionnaire like the one used in this evaluation. In order
to tap into the richness of users’ interaction with the prototypes I made voice
recordings during the course of interaction. From these recordings I have made
some observations that I find interesting.
participants of the evaluation used the direct manipulation prototype the
typical behavior was of an explorative kind. They tried to make sense of the
interface by dragging the different sliders to the left and right just to see
what happened. Some were very careful while others, rather violently, shoved
the sliders around between the extremes. Based on that observation, the
participants did not seem to have problems to make sense of what was going on
at the user interface.
contrary to the direct manipulation interface, the interactive evolutionary
design prototype seemed to be more of a challenge concerning the meaning
attributed to the interface and the hidden mechanisms behind it. It seems as if
the subjects in a very active way during the course of interaction tried to
develop mental models [1, 10] of the system, that is, they tried to develop
theories that could explain the behavior of the program they were using.
Notably, some subjects tried to figure out the relation between the typefaces
they selected and the new typefaces that were generated from the selection.
Some subjects seemed to try to make sense of this relation as a kind of average
relation. The following quotation shows how one subject made this very explicit
(translated from Swedish):
Well, you do not really know how he [the computer]
does it, you don’t know if it pays off to take one extreme at one end and one
extreme at the other end and believe it will become something in between. I
used a vocabulary that included words such as “mixing”, “blending” and other
words that I take to imply an understanding of the generative mechanism as an
averaging of parameters, not a recombination. Also of interest is that some
subjects seemed to attribute meaning to the order in which newly generated
typefaces were presented in the list. However, the program is not designed to
do any kind of sorting. Nonetheless, some subjects seemed to experience the
typefaces at the top of the list as having more in common with the ones they
selected from the previous generation of typefaces. As a response to my
question, if he could recognize the qualities of the selected typefaces in the
generated set, one subject responded:
Several of the first ones are variations of the two I
selected, until you come down here [the person scrolls down the list]. I would
say that it varies so much that I can’t say that [there is a resemblance with
the two previously selected].
It is not
obvious how to assess the significance of this kind of interpretation of the
interface, but it seems likely that it may affect the outcome of that which is
being designed. If objects at the end of the list are experienced to be of less
of interest users may tend not to select them.
Convergence and surprise
previously, the results from the questionnaire seem to point in the direction
that interactive evolutionary design is more preferable for tasks where the
goal in not clearly and explicitly defined. Partly, a reason for that may be
that interactive evolutionary design is based on the presentation of examples,
the creator is given something to react to. Indeed, the whole point of this
approach is to use these reactions as a driving force in design processes.
However, one crucial aspect seems to be to strike a balance between how this
force is used to cater for convergence of the design and the degree of
surprise. On the one hand, user reactions to design examples must be handled in
a way that adapts, in this case, the typeface design to the expressed user
preferences. On the other hand, a supportive system should also allow for some
amount of surprise and unexpected designs. If this balance is found, it may be
possible to achieve a dynamic relation between the user’s preferences and the
behavior of the computer program. Put differently, if such a balance is found,
interactive evolutionary design may not only be used as a tool to externalize a
mental vision of that which is being designed, but also change such visions, by
means of presenting the unexpected.
the participants of the evaluation it appeared as if some of them experienced
both a high level of convergence and some amount of surprise. For instance,
when one of the participants used the interactive evolutionary design prototype
to design the Caveman logotype he suddenly noticed a generated typeface and
Wow! This one felt very much like the Godfather [the movie]! That’s
cool. I’ll take the godfather.
At the end he
selected a “Godfather”-like typeface as the typeface for the logotype. Other
participants expressed similar experiences that pointed in the direction that
they could recognize their selections in the generated typefaces at the same
time as some typefaces were very unexpected. Some reacted quite strongly when
they saw something that had not expected and that kind of reaction was rare for
the direct manipulation interface, probably due to the fact that direct
manipulation – as implemented in my prototype – makes it possible for users to
continuously see what is happening while changing one parameter at a time. The
balance between convergence and surprise is of course heavily dependent on the
probability for mutation. Initially, I considered allowing the participants to
vary the mutation rate as they liked but decided that it would make a
comparison of user experiences almost impossible, considering that mutation
rate affects the outcome very dramatically.
investigation suggests that the participants clearly experienced that the
direct manipulation interface provided better support for affecting the design
of the typefaces. However, from my observations of the experiment sessions,
interactive evolutionary design appears to have supported creativity in a way
that direct manipulation did not. This is also confirmed by the participants’
inclination to experience interactive evolution as more suitable for creative
tasks. In this context, it is interesting that the experienced activity level
was significantly lower for interactive evolutionary design prototype compared
to direct manipulation. In a way, it may be interpreted as if we get more by
It is an open
issue to what extent we can generalize from the results of this investigation
to other kinds of design spaces and other contexts. However, it seems to me as
if one lesson to learn from the investigation is that the important issue is
not what interaction style is better than the other. Rather, I would suggest
that a multitude of different modes of interaction, including direct
manipulation and evolutionary approaches, should be combined to cater for the
need imposed by situation and individual preferences.
Robert B. (1997) Mental Models and User Models. In M. Helander, T. K. Landauer,
P. Prabhu (eds.). Handbook of Human-Computer
Elsevier Science B. V.
Peter J. (1999). Evolutionary Design by
Computers. Morgan Kaufmann.
I. And Lewis, M. (2000). Web-page: Evolving Fonts.
Rikard. (1999). Evolutionary Banners: an Experiment with Automated Advertising
Design. In Proceedings of COTIM-1999.
Rhode Island, RI, USA, September 26-29.
E. L., Hollan, J. D. and Norman, D. A. (1986). Direct manipulation interfaces.
In D. A. Norman and S. W. Draper (Eds.) User
centered system design, 87-124. Hillside, NJ: Lawrence Erlbaum Associates,
D. E. (1999). Digital Typography.
CSLI Publications. Stanford. Ca.
M. (2000). Web page: Visual Aesthetic Evolutionary Design Links.
Patti. (1994). Agents that reduce work and information overload. In Communications of the ACM. Vol. 37, No.
7 (pp. 31-40, 146).
Melanie. (1996). An introduction to
genetic algorithms. The MIT Press.
10. Norman, D. A. (1988). The Psychology of Everyday Things. New
York: Basic Books.
11. Shneiderman, Ben. (1977). The future
of interactive systems and the emergence of direct manipulation. In Behaviour and Information Technology. Vol 1, 237-256.
12. Shneiderman, Ben. (1982). The future of interactive systems and
the emergence of direct manipulation. In Behaviour
and Information Technology. Vol 1, 237-256.
13. Shneiderman, Ben. (1997). Direct Manipulation for Comprehensible, Predictable, and Controllable User Interfaces. In Proceedings of IUI97, 1997 International Conference on Intelligent User Interfaces. Orlando, FL, January 6-9, 1997, 33-39.
14. Shneiderman, Ben. (2000). Creating
Creativity: User Interfaces for Supporting Innovation. In ACM Transactions on Computer-Human Interaction, Vol. 7, No. 1,
15. Sims, K. Artificial Evolution for
Computer Graphics. In Computer Graphics, 25 (1991) 319-328.
16. Tinkel, K. (1995). Mastering
multiple masters. In Adobe Magazine,
17. Todd, S. and Latham, W (1999). The
Mutation and Growth of Art by Computers. In Bentley, Peter J., Evolutionary Design by Computers. Morgan