Investigating Positive and Negative Qualities of Human-in-the-Loop Optimization for Designing Interaction Techniques
This addresses the challenge for novice designers in HCI who struggle with multi-objective optimization, though it is incremental in evaluating an existing method in a realistic context.
The paper tackled the problem of assisting novice designers in complex design optimization tasks by using Bayesian optimization as a human-in-the-loop method, finding that it helped them explore 40% more of the design space and achieve better solutions, but reduced their reported agency and creativity.
Designers reportedly struggle with design optimization tasks where they are asked to find a combination of design parameters that maximizes a given set of objectives. In HCI, design optimization problems are often exceedingly complex, involving multiple objectives and expensive empirical evaluations. Model-based computational design algorithms assist designers by generating design examples during design, however they assume a model of the interaction domain. Black box methods for assistance, on the other hand, can work with any design problem. However, virtually all empirical studies of this human-in-the-loop approach have been carried out by either researchers or end-users. The question stands out if such methods can help designers in realistic tasks. In this paper, we study Bayesian optimization as an algorithmic method to guide the design optimization process. It operates by proposing to a designer which design candidate to try next, given previous observations. We report observations from a comparative study with 40 novice designers who were tasked to optimize a complex 3D touch interaction technique. The optimizer helped designers explore larger proportions of the design space and arrive at a better solution, however they reported lower agency and expressiveness. Designers guided by an optimizer reported lower mental effort but also felt less creative and less in charge of the progress. We conclude that human-in-the-loop optimization can support novice designers in cases where agency is not critical.