The literature on face emojis raises the central question whether they should be treated as pictures or conventionalized signals. Our experiment addresses this question by investigating semantic differences in visually similar face emojis. We test a prediction following from a pictorial approach: small visual features of emojis that do not correspond to human facial features should be semantically less relevant than features that represent aspects of facial expressions. We compare emoji pairs with a visual difference that either does or does not correspond to a difference in a human facial expression according to an adaptation of the Facial Action Coding System. We created two contexts per pair, each fitted to correspond to a prominent meaning of one or the other emoji. Participants had to choose a suitable emoji for each context. The rate at which the context-matching emoji was chosen was significantly above chance for both types of emoji pairs and it did not differ significantly between them. Our results show that the small differences are meaningful in all pairs whether or not they correspond to human facial differences. This supports a lexicalist approach to emoji semantics, which treats face emojis as conventionalized signals rather than mere pictures of faces.

Recent criminal psychology research has raised critical questions about applying non-verbal communication methods for lie detection purposes in forensic settings. Research has shown low correlations between non-verbal communication and deception. However, non-verbal communication methods are still widely applied and suggested by police manuals. Results obtained by experimental and field research are biased by the following factors: (i) attention is given only to quantitative aspects of non-verbal behavior; (ii) there is a lack of research of qualitative aspects related to non-verbal behavior analysis; (iii) lack of connections between non-verbal indicators and verbal content; (iv) lack of attention on timing of non-verbal behavior; (v) most research is performed on psychology students in experimental contexts. This article proposes a new methodology for applying the Facial Action Coding System as investigative support and not as a lie detection method. The Facial Action Coding System will be introduced to integrate with verbal content analysis and a new framework to interpret non-verbal signs discussed. The aid of standardized non-verbal methods will be discussed through an in-depth psychological analysis of a case of homicide perpetrated in 2010 in Southern Italy by discussing a video analysis of the suspects’ statements.