RESEARCH ON INFORMATION UNDERSTANDABILITY IN INTERFACE DESIGN Svetla Vassileva, Sofia Anguelova Abstract: This paper describes a research on the information understandability in software interface design. The study took place with Bachelor Degree students in their laboratory work in Software Ergonomics at the Technical University of Sofia. The goal is to find the optimal solution for displaying information content according to Gestalt principles. The research is focused on the relationship between information understandability and different interface layouts, colour schemes, metaphors and text visualizations. Subjective factors as users’ expectations and experience are also considered in interface design process. Keywords: software ergonomics, interface design, Gestalt principles, visual communication, engineering design education INTRODUCTION The study of visual perception offers the evidence that images of the world are not “given”, but constructed. Gestalt is a term coined by German psychologists in the 1920s which means "unified whole" and refers to the human visual perception. This theory attempts to describe how people tend to organize visual elements into groups or unified wholes. According to the Gestalt theory in the process of visual perception the following fundamental principles are applied: similarity, proximity, continuity, closure and symmetry [1, 3, 4].  similarity - features which look similar are grouped together perceptually. Items can be grouped based on similar color, shape, size, etc. Researches have shown that similarity by color and shape is a stronger grouping mechanism that using similarity by other traits such as contours.  proximity - Features that are spatially close together are associated.  continuity - The lines based on smooth continuity are preferred over abrupt changes of direction.  closure - Interpretations which produce 'closed' rather than 'open' figures are favoured. Our minds react to patterns that are familiar, even though we often receive incomplete information.  symmetry - symmetrical areas tend to be seen as figures against asymmetrical backgrounds. THESIS The main idea behind the so called principles of Gestalt that “the sum of the whole is greater than its parts” means that each of the individual parts has meaning on their own, but the meaning may change when they are taken together. Thus, in the case of a GUI we are interested in the perception of its components and composition of these components as a whole, since human’s perception of the piece is based on our understanding of all the pieces working in harmony.