ELSEVIER Knowledge-Based Systems 9 (1996) 351 358 Knowledge-Based ,, 5 V S T E I ' q f f - - - Participatory theater: interacting with autonomous tools for creative applications James Ambach*, Alexander Repenning Department (if Computer Science, CenterJor LifeLong Learning and Desigm UniversiO'o/Colorado, Boulder. CO 80309-0430. USA Abstract Creating art can be seen as creative exploration through a design space defined by the artist and the tools. Artistic tools such as brushes and chisels are passive, stressing direct manipulation interaction that leaves exploration to the artist. If tools were more autonomous, creativity could be enhanced by allowing the artist to delegate aspects of exploration. We describe a software environ- ment called Agentsheets that combines direct manipulation and delegation into an interaction scheme called participatory theater. The advantages of this approach are described in the context of two drawing applications. Art Pals and Art Dwarves, that involve the computer more actively in exploration. We also explore the utility of participatory theater in the physical world by describing our experiences developing and using autonomous painting robots in conjunction with a professional artist. Keywords: Direct-manipulation: Delegation; Participatory theater; Agentsheets 1. Introduction: exploring design spaces Both engineering and art can be viewed as points along the spectrum of design space exploration. Typi- cally, engineering design calls for the satisfaction of several constraints |tlvolving cost, system requirements, building materials and many other concerns [1]. Form is heavily influenced by function, and these constraints limit the design space to be explored. Art, on the other hand, is more concerned with form and aesthetic appeal. The only constraints that need to be satisfied are the subjective constraints imposed by the artist and the objective constraints imposed by the selected medium and tools. Existing artistic tools such as brushes and chisels are of a passive nature stressing a direct manipulation inter- action scheme which leaves the exploration to the artist. This paper advocates the inclusion of autonomous tools in the exploration process and discusses the role of users of such tools. In a computational medium, direct manipulation allows a user to move through a design space by applying tools in a very predictable fashion. The emphasis of direct manipulation is based primarily on temporal con- straints and calls for tools that provide the user with the * Email ambach(a,!cs.colorado.edu 0950-7051/96/$15.00 ~"~ 1996 Elsevier Science B.V. All rights reserved PH S0950-7051 (96)01046-5 means to perform rapid, incremental and reversible actions whose impact is immediately recognizable [2,3]. Unfortunately, not all computation can be forced to adhere to these time constraints for reasons of computa- tional complexity. In these cases direct manipulation often resorts to pacifiers such as watch cursors, ~), that prevent users from any kind of manipulation. In some cases, users may not be interested in con- trolling every aspect of a computation and would gladly delegate tasks to the computer [4]. For instance, delegation can enable artists to explore regions of a design space that were not previously anticipated. How- ever, delegation comes at the cost of losing control over the exploration process. Complete delegation of tasks is, therefore, undesirable. It is important to estab- lish a setting where the user is not just a passive critic of tool activity, but rather a co-participant with the computer [5]. We argue that there is a need for tools that enable artists to move through design spaces in different ways. These tools should (i) support direct manipulation as well as delegation and (ii) support the combination of these two approaches in ways that allow the computer and the artist to explore in parallel. This paper outlines a human-computer interaction scheme called partici- patory theater that is based on a combination of direct manipulation and delegation. It briefly describes a