The Gestalt principle of closure refers to brain activity filling in missing information to perceive objects as complete, even when partially hidden. Designers leverage this principle to imply shapes without explicitly showing them. However, evaluating viewer responses poses challenges. The author conducted a comprehensive eye-tracking experiment to determine when viewers mentally completed a gap in a circle and explored the potential influence of the golden ratio on the closure principle. The golden ratio, approximately 1.618, is associated with visual harmony and is used in art and design to create pleasing proportions. Findings showed that viewers tend to mentally close gaps up to 135° but avoid closure beyond 150°. This suggests the golden ratio’s relevance in applying the closure principle to design.

In this study, the authors use a novel eye-tracking technology to determine how viewing behavior complies with Wertheimer’s descriptions of Gestalt principles of similarity, proximity, continuation and closure. The results show that viewers respond predictably to most Gestalt principles and that there are nuances to note when it comes to better understanding the role of visual attention in the closure principle and competing principles. In addition, the results reveal a fundamental distinction between visual attention and visual perception. By grasping this critical difference between attention and perception, designers may become more successful in applying Gestalt principles to their design.