The intentionality of influence: Disentangling usability optimisation from nudging in design

Nudge theory proposes to deliberately alter people's behaviour or choices in a predictable manner. In the literature on nudging, certain functions in product and system designs, such as automatic switches in car headlights and default settings in computers and cell phones, are presented as nudges when, in fact, these functions do not meet the conditions for being nudges. These examples are clear cases of usability measures to optimise the products more effectively and efficiently, and hence, using them in the context of nudging is very misleading. This conflation between nudging and usability measures often obscures the proper conceptual boundaries of what qualifies as a nudge. Therefore, calling usability measures as nudges is, at best, unhelpful and, at worst, problematic. In this article, we will attempt to tease out the cases of usability from nudging by outlining the necessary conditions of nudges and usability measures from their definitions. We will elaborate on our case with certain examples of usability measures, which are referred to as nudges in the literature, and demonstrate that these cases do not meet the necessary conditions for nudging. This distinction between nudging and usability measures will contribute to a more precise conceptual understanding of what qualifies as a nudge, which is inevitable for further research on nudging and its design. • Study proposes a critical theoretical distinction between usability optimisation and nudge design. • Establishes the necessary and sufficient conditions for a nudged choice architecture. • Clarifies conceptual boundary for behavioural design by rigorously defining what qualifies as a nudge. • Argues that usability measures optimise human-artefact interaction, not individual choices for welfare. • Identifies how conflating usability with nudging creates a category error.