# Evaluation of Effective Cognition for the QGIS Processing Modeler
## 1 Introduction  
Today, open source GIS software competes with commercial GIS software. The user's choice not only depends on the price but also the degree of functionality in parts of the GIS software. Users need to satisfy their requirements. One of the demands is the automatic processing of spatial data as a sequence of steps. Visual programming languages (VPLs) are used to design steps of processes in the form of workflow diagrams. GIS operations are not used in isolation but as a part of a chain of operations to completely process data. An overview and basic description of several visual programming languages in GIS are given in this article [1]. ModelBuilder for ArcGIS, Macro Modeler for IDRISI, Model Maker and Spatial Model Editor for ERDAS IMAGINE and Workflow Designer for AutoCAD Map 3D are mentioned. All systematic description and evaluation of VPLs in GIS is presented as habilitation [2]. VPLs in GIS are data-centric notations that serve to express a process in detail. Only AutoCAD Map uses hybrid symbols where one symbol both for operation and input/output data altogether is. Other VPLs have a unique set of simple symbols for data and unique symbols for operations and control of flow. GIS workflow does not express a generalised conceptual model of processing, and they are more detailed.  
Open source software QGIS is competitive with commercial GIS software in designing workflow diagrams using VPL. The accessibility of a visual programming language increases the usability of QGIS. The possibility of designing workflows could be a reason for selecting open source QGIS.  
The Processing Modeler is a graphical editor in QGIS software. This editor allows workflows to be designed in graphical form using a visual programming language. Workflow diagrams in QGIS are termed as a model.  
VPLs differ in their visual notation generally, and the symbols in GIS software are various. The visual notation consists of graphical symbols (visual vocabulary), a set of compositional rules (visual grammar) and definitions of the meaning of each symbol (visual semantics). The visual notation is important from the point of user perception and cognition. In his theory, the Physics of Notations, [PERSON] stated that it is necessary to use cognitively effective visual notations [3]. Cognitively effective means optimised for processing by the human mind.  
This article presents an assessment of the visual notation of the QGIS Processing Modeler using the Physics of Notations theory in combination with eye-tracking measurement. The presented research started with version QGIS 2 in 2014 and has been continued with version 3 up to now. The long-term release (LTR) version QGIS 3.4 Madeira and partly version 3.6 Noosa was used for assessment. Some features of visual notation were empirically tested using the eye-tracking method on version QGIS 2. Finally, some improvements to visual notations are suggested in this article.  
The research question was \"What is the level of effective cognition in QGIS Processing Modeler.\" This research aimed to evaluate and improve cognition of visual notation in QGIS. The results bring new and innovative ideas that improve the usability of and satisfaction with QGIS software.  
These tasks fall under investigation in Human-Computer Interaction (HCI) research. Standard ISO 9241-210:2019 Ergonomics of human-system interaction--Part 210: Human-centred design for interactive systems [4] provides requirements and recommendations for human-centred design principles and activities of computer-based interactive systems. In the center of HCI research and UX research (User Experience), is the understanding and design of interactive digital systems and their human users [5]. Their common aim is to innovate novel computing user interfaces to satisfy usefulness, ergonomics, and efficiency of using digital systems [6; 7]. The improvement is based on theories and both on empirical testing in laboratories [8] e.g., the eye-tracking measurement presented in this article.