Margherita Andrao, Barbara Treccani, Massimo Zancanaro

This paper presents a qualitative study that investigates the effects of some language choices in expressing the trigger part of a trigger-action rule on the users' mental models. Specifically, we explored how 11 non-programmer participants articulated the definition of trigger-action rules in different contexts by choosing among alternative conjunctions, verbal structures, and order of primitives. Our study shed some new light on how lexical choices influence the users' mental models in End-User Development tasks. Specifically, the conjunction "as soon as" clearly supports the idea of instantaneousness, and the conjunction "while" the idea of protractedness of an event; the most commonly used "if" and "when", instead, are prone to create ambiguity in the mental representation of events. The order of rule elements helps participants to construct accurate mental models. Usually, individuals are facilitated in comprehension when the trigger is displayed at the beginning of the rule, even though sometimes the reverse order (with the action first) is preferred as it conveys the central element of the rule.