The Implicit Relational Assessment Procedure (IRAP) has been successfully used to analyze the strength of symbolic relations. Taking advantage of this, Bortoloti, de Almeida, de Almeida, and de Rose (Frontiers in Psychology, 10(954), 2019) reported a higher relational strength in equivalence classes containing happy faces than in those containing negative faces. This so-called happiness superiority effect (HSE) was inferred from an IRAP that included stimuli presented during the equivalence training. Such HSE apparently had a stronger influence on IRAP performance than the equivalence training itself. In this article, we comment on these data and present a new analysis that supports a hypothesis raised by Bortoloti et al. (Frontiers in Psychology, 10(954), 2019) to account for a surprising IRAP performance in their experiment. Based on this, we discuss new avenues for the investigation of properties of relational responding using the IRAP.