Into the Archives: A Look Back with “Robotic Artist” Harold Cohen

Editor’s note: Curator Chris Garcia delved into the Museum’s institutional archive and uncovered a rare 1995 interview with computer art pioneer Harold Cohen, taken during The Computer Museum’s exhibition “The Robotic Artist: AARON in Living Color” (April 1−May 9, 1995). The selection below appeared in TCM’s annual report that year and was excerpted from the full interview published in the exhibition catalog. 

The Robotic Artist: AARON in Living Color

The Computer Museum hosted the world premiere of AARON, an expert system with its own painting machine built by artist Harold Cohen. Each day, the computer-driven robot controlled by AARON created an original color painting. From its first creation—recorded live on Today March 31—AARON captured the imagination of thoughts of Museum visitors and media worldwide. (An earlier, simpler version of AARON, which made black and white line drawings, engaged Museum visitors from 1987−1994.)

What follows are highlights from a conversation between Cohen and photographer Becky Cohen in March. Both art and text are excerpted from the exhibition catalog she created.

BC: AARON has been making drawings autonomously for more than two decades, and now you are celebrating its new ability to color its drawings with dyes and special brushes. How did you get it to paint?

HC: Putting dye on paper is easy: You just build a machine! This one consists of a small robot arm carried around over a large flat table on what we call an “xy device.” The arm has a “hand” that’s able to pick up the cups and brushes . . . located at the edges of the table, it manipulates the taps on bottles of dyes, and so on.

Of course, I’m joking about it being easy to build a painting machine. The truth is that it was a relatively straightforward task compared with writing the code that would give AARON the ability to think about color. That has been my major preoccupation the past two or three years, and there would have been no point in building a machine if I hadn’t been able to do it.

BC: What people see in the Museum is the machine painting. What they can’t see is how AARON is thinking about color. . . . Why was color a difficult problem?

HC: Human beings can see the results of putting two colors next to each other and can proceed on the basis of this feedback. The program is able to keep a . . . complete record of what it’s doing, but it can’t see in the same sense that you and I can. I had to come up with rules about color juxtaposition that would serve in place of visual feedback that humans use. As a painter, with a lifetime of experience of color, I must obviously have known what some of those rules were, yet I found it frustratingly difficult to say what they were.

AARON Paint System on exhibit in Revolution: the First 2000 Years of Computing

AARON Paint System on exhibit in Revolution: the First 2000 Years of Computing

BC: Were you able to rules you had built for the screen-based coloring program onto the coloring program for the painting machine?

HC: Well, actually not. I spent some time trying to translate the red-green-blue mixtures that AARON specified into combinations of the dyes I was using, but it never worked to my satisfaction. It turned out that I could only translate about half of AARON’s colors; rather obvious, actually, since dyes can’t possibly be as bright as the colors you see on the screen. Finally I abandoned that approach and started to build up a new version based directly upon the dyes.

BC: What kind of dyes have you chosen? And why dyes? Do they suffer from impermanence?

HC: Oh no, not at all. That was true in the nineteenth century, with some of the earliest industrial dyes, but no longer. I have a shirt that’s been in the California sun for almost two decades and in and out of the washing machine I don’t know how many times; it still has most of its original color.

I’ve been using these Procion fabric dyes for several years for working on paper; they’re very beautiful in color and they all rate six or seven on a permanence scale from one to seven.

BC: What programming languages do you use?

HC: AARON is written in LISP and runs on a Silicon Graphics computer, while the painting machine is controlled by a PC—a generic 486—and the program is written in C++.

When AARON generates a painting, it stores it in a file as a set of instructions. Most of these instructions will control the movement of the brush on the paper, both in making the initial drawing and in filling in the color. Some of them specify the mixing of dyes for individual areas of the painting, and some of them specify the size of brush to be used. The file is read over a network connection by the 486 which then interprets those instructions and scales the dimensions of the Silicon Graphics screen to whatever size drawing is being made. It also scales the volume of the dye to be mixed for any color and the size of the brush, and then it generates the lowest-level commands that drive the painting machine.

To do everything it is supposed to do, the 486 program has to control the movement of the arm across the table, the horizontal rotation of the shoulder, the vertical rotation of the elbow, two rotations of the wrist, the opening and closing of the hand, and the reach—how far the hand can extend from the elbow. The program also has to know where the cups and brushes are kept, where the tap handles are and how much to move them up and down, and so on.

Detail of the first image created at the Computer History Museum by the color-enabled version of AARON, 1995

Detail of the first image created at The Computer Museum by the color-enabled version of AARON, 1995. Collection of the Computer History Museum, 102741168.

BC: So, the order of events is: AARON first generates the drawing, then the coloring for the drawing, and finally sends orders to the 486. AARON never thinks about coloring before drawing, does it?

HC: No, the drawing is done first, and then AARON decides about color. But the coloring part doesn’t only involve the color choice. It must also map out the path the brush must take filling in the various shapes in the drawing.

BC: Yes, I could see the brush following the internal contours of shapes as it was coloring; but it seems that AARON must also have a sense of portraiture: that it has some idea of what sorts of color might be good for clothing, or plants.

HC: AARON has a very clear idea of what it is doing.

BC: How does AARON assign color?

HC: In AARON’s understanding of the drawings, different elements are characterised by their different attributes. It knows, for example, that a face has two eyes, and it will never draw a face with three. To the degree that color is also an attribute of a face, there are a limited number of colors it can use. It would never decide to paint a face green because it doesn’t believe that faces can be green. However, there is no such limitation on the assignment of colors to things like sweaters or backgrounds. Color assignment here reflects the program’s concern for the color “signature” of the whole painting. If AARON decides to do a red sweater, for example, it will probably not decide to do a red background. . . .

When I started work on the painting version of AARON. I was struck by the fact that we have a very poor vocabulary for talking about color relationships, and that almost all of what’s been written as color theory has been either theory about color perception or theory about color measurement. There is almost nothing about color use. . . . Whenever I find myself faced with a problem about how the program should proceed, I’ve asked myself how I would proceed. I was deeply frustrated to find that I couldn’t describe what was happening in my own head when I was manipulating color as a painter.

BC: Your pictures tend to he sort of two-and-a-half dimensional: not 2-D, not 3-D, but somewhere in between—sort of like Pompeian frescoes.

HC: All representation is two-and-a-half dimensional, isn’t it? The viewer is always confronted with a flat surface that evokes something in the physical—3-dimensional—world. . . . It seems to me that the last 500 years of Western culture have been quite aberrant with respect to world history. At no other time in human history will you find our own characteristic obsession with appearances, nor its consequence, which led to the underlying technology both for photography and for computer graphics—the reflection of light off the surfaces of things in the world. That’s a mystery to me. Do we really believe that we can find out the truth by the way things look?. . .

AARON image created at the Computer Museum, Boston, 1995

AARON image created at The Computer Museum, Boston, 1995.

BC: You seem to have created a sort of magical space where AARON ‘s “organisms,” figures, and plants have a special interrelationship with each other. Even in the room-like environments, it is as if the figures have a truly imaginative relationship with each other.

HC: I . . . hesitate on the word “imaginative” because that implies capabilities to the program that I know perfectly well [it] doesn’t have. AARON’s domain of expertise is the building of representations, not knowledge of the outside world. Hmm . . . Well, it has some knowledge of the outside world.

BC: Like what?

HC: For example, it knows how people are put together. It knows how they are capable of moving. It knows how plants grow. It knows that rooms have walls at the back. It knows all of those things, though that isn’t to say that it knows them in the same way that you or I know them. I suspect that whatever success the program has had has rested upon devising a representational mode perfectly fitted to the structure of its knowledge.

BC: It seems that you reinvented drawing as a means of reinventing color.

HC: I was becoming increasingly disturbed and antipathetic towards the whole modernist movement in painting, in art. We had turned painting into a very specialized game that only a very few people could understand and respond to. I have always felt that the health of any art depends upon its relationship to the culture it serves, and I wasn’t happy with where I stood . . . I suppose that in turning away from color to spend several years investigating drawing, I was beginning to look for a way of getting back to a kind of imagery that would be available to more people. . . . Over time, I began to think that there was something slightly unsatisfactory about having AARON do all these drawings that I was then required to color.

BC: From the beginning of your dialogue with your creation, you have always wanted its work to qualify according to your own high standards of interest, use, and beauty.

HC: Of course, why would I demand less of it? One of the bargains I made with myself from the earliest days was that I would never accept the position of having to apologize because this was done by a computer. I have always insisted that the work the program did would have to stand on equal terms with art made by hand.

BC: Still, you want what you’ve modeled in AARON and AARON ‘s drawings to be truly within the domain of art. Presumably that is why you’ve spent so much time running the other way from so-called “computer art.”

HC: Yes. But . . . my goals have changed subtly over the years. For a very long time, I thought AARON’s work should be indistinguishable from the work made by human artists. That isn’t quite the case any more. I want the work to look as if it has been made by an intelligence, but it doesn’t have to be a human intelligence. I am much happier now when I see the program produce an image that looks as if it had been made by somebody who is seeing the world for the first time: seeing the world from a different point of view from someone who grew up human.

BC: You give AARON a rather innocent quality, placing it just at the boundary of discovery all the time. I am wondering if you are ever surprised by any of the actions AARON takes. . . .

HC: I know exactly what AARON knows, but I can still be surprised. When you work on a program as I’ve worked on AARON, you make the program the heir to some subset of your own knowledge. When it plays that knowledge back to you, you can find yourself saying, “Hey, where did that come from? I didn’t realize that that is what I believe.” In that sense the whole endeavor is quite a shocking and remarkable experience. . . .

BC: Yet AARON has taught you something.

HC: AARON is teaching me things all the way down the line. From the beginning, it has always been very much a two-way interaction. I have learned things about what I want from AARON that I could never have learned without AARON.

BC: So, this decades-long conversation with AARON has enabled you to build on your own understanding of your own knowledge. AARON is probably the oldest, continuously developed artificial intelligence program in computing history at this point. It has also allowed you to create a new medium for yourself as an artist, even to redefine what we mean by art.

HC: Interestingly enough, I think the very age of the program contributes a great deal to the quality of what it does. Whatever else happens after twenty years of continuous development, AARON has a kind of complexity . . . that you won’t get when you sit down and knock off a program in three months or three years.

BC: Who are the people in the picture that AARON draws right now?

HC: Oh, well! One of them turned out to be someone I taught as a graduate student years ago. One of them is a graceful black woman whom I have never met but who I think would be wonderful to talk to. The amazing thing to me is the frequency with which the drawings turned out to look like people I know. . . .

Of course, there are no human models, and the program is not attempting to portray any given individual. Only once did I ever get it to portray a particular person with reasonable success, and I found the enterprise rather uncomfortable . . . It was like manipulating a rather complicated police identikit.

BC: What traditional artistic goals have you been escaping for the last quarter century by casting your lot with artificial intelligence?

HC: I am not sure I am escaping any goals, or even trying to. Oh, of course it isn’t exactly traditional to have a machine generate one’s artworks. But—in the twentieth century—certainly artmaking is a highly self-reflective activity, and what is central is the degree to which the making o fart contributes to an ongoing dialogue about the nature of art. In that sense think my work is absolutely orthodox.

I have never subscribed to what was once called the telecommunication model of art: the artist has something in mind which is encoded in a message and sent across the art medium, or the Internet, or whatever, and is then received and decoded, with the result that the audience understands just what the artist had in mind. . . . The artist is concerned with the design of meaning generators, not meaning communicators. The power of the program still is that it is capable of generating some personality on a piece of paper; it will initiate some response on the part of the viewer in terms of what the viewer knows about human personality and human experience.

BC: What artistic future are you indicating with your work?

HC: Public attitudes towards computers are by no means neutral. In a market-driven society, the manufacturer shoots for the biggest possible, not the most sophisticated, market. . . . The vast majority of users today identify the computer as a box on which to run ready-made packages. . . . There is no package for what I do, and there couldn’t possibly be … using one would be absolutely antithetical to the artist’s position. . . . I am in the fortunate position of having been in this game from the time when there weren’t any packages to be bought . . . if you wanted a program, you wrote one.

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