Choosing the new graphical representations of this extension 

The new symbols proposed by this extension for Organisation, Environment, Perception and Planning were created using an experiment based on the work of Caire et al. (Caire, P., Genon, N., Heymans, P., Moody, D. Visual notation design 2.0: Towards user comprehensible requirements engineering notations. 21st IEEE International Requirements Engineering Conference, 2013). 

We performed this five-steps experiment with 152 participants. We created graphical representations for these concepts to be used in the studies 4 and 5 of this experiment. 70 participants made drawings for these four concepts (Step1). Following, we analysed the drawings, grouped them and identified the stereotype of the population (the most significative drawing from the most frequent group) (Study 2). Then, we submitted questionnaires to identify the prototype (Study 3) to 29 participants, the semantic transparency (Study 4) to 48 participants and the recognition (Study 5) to 45 participants. The graphical representations of the subsets are presented in the figure below. 

We presented the results of the Hit rate of study 4 (Semantic transparency experiment) in the table below. Bolded values indicate the best hit rate of a concept among all factors.

Hit rate (in %) means per concept per factor in Semantic Transparency experiment

We presented the results of the Hit rate of study 5 (Recognition experiment) in the table below. Bolded values indicate the best hit rate of a concept among all factors.

Hit rate (in %) means per concept per factor in Recognition experiment

Finally, we selected symbols based on results of studies 4 and 5. These symbols are used in this extension to represent the new concepts. The Figure below shows the selected symbols.