Testing of Perceptual Discriminability in Workflow Diagrams by Eye-Tracking Method

Workflow diagrams are used for the design of steps of the algorithm in spatial processing data in geographic information system (GIS). The colour fills, and various shapes are used for basic symbols in the workflow diagram vocabularies. The Perceptual Discriminability and Visual Expressiveness are two basic principles of the theory Physics Notations. This theory revealed the zero visual distance between yellow Built-in Tool symbol and Script Tool symbol (resp. Sub-model symbol) in ArcGIS ModelBuilder. The eye-tracking experiment tested the influence of increasing the visual distance of symbols in workflow diagrams on the user cognition. The visual distance was increased by a change of fill colour for two mentioned symbols. Eye-tracking measuring brought objective results and affirmed that diagrams, where symbols have better perceptual discriminability, have an average lower time of response, lower number of fixations, and shorter length of scanpath. The result is a recommendation for changes of symbols in the visual vocabulary of ModelBuilder that introduce two new symbols for Script Tool and Sub-model.