An extended abstract for submission to 3rd International Conference and Exhibition on Generative Art, 14/15 December 2000, Politecnico di Milano University, Milan, Italy.

Evolving the Shape of Things to Come

A Comparison of Interactive Evolution and Direct Manipulation for Creative Tasks

Andreas Lund
Interactive Institute & Department of Informatics, UmeŚ University
Tel. +46 90 18 51 34

This paper is concerned with differences between direct manipulation and interactive evolutionary design as two fundamentally different interaction styles for creative tasks. Its main contribution to the field of generative design is the treatment of interactive evolutionary design as a general interaction style that can be used to support users in creative tasks.

Direct 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.

Undoubtedly, 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. Also, the possibilities of incremental action with continuous feedback are believed to be an important factor of the attractiveness of direct manipulation.

However, direct manipulation is also associated with a number of problems that make it a less than ideal interaction style in some situations. Recently, new interaction paradigms have emerged that address the shortcomings of direct manipulation in various ways. One example is 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.

Another emerging 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 biological evolution and may be described as a way of exploring a large Ė potentially infinite Ė space of possible design configurations based on the judgement of the user. 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 judgement of design examples. Variations of interactive evolutionary design have been employed to support design and creation of a variety of objects. Examples of such objects include artistic images, web advertising banners and facial expressions.

In order to make an empirical investigation possible, two functional prototypes have been designed and implemented. Both prototypes are targeted at typeface design. The first prototype allows a user to directly manipulate a set of predefined attributes that govern the design of a typeface. The second prototype allows a user to iteratively influence the design of a typeface by means of expressing her judgement of typeface examples. Initially, these examples are randomly generated but will, during the course of interaction, converge upon design configurations that reflect the userís expressed subjective judgement.

In the evaluation of the prototypes, I am specifically interested in usersí sense of control, convergence and surprise. Is it possible to maintain a sense of control and convergence without sacrificing the possibilities of the unexpected in a design process? The empirical findings seem to suggest that direct manipulation caters for a high degree of control and convergence, but with a small amount of surprise and sense of novelty. The interactive evolutionary design prototype supported a lower degree of experienced control, but seems to provide both a sense of surprise and convergence. One plausible interpretation of this is that, on the one hand, direct manipulation is a good interaction style for realizing the userís intentions. On the other hand, interactive evolutionary design has a potential to actually change the userís intentions and pre-conceptions of that which is being designed and, in doing so, adds an important factor to the creative process.

Based on the empirical findings, the paper discusses situations when interactive evolutionary design may be a serious contender with direct manipulation as the principal interaction style and also how a combination of both styles can be applied.