Flury-Riedwyl faces are visual representations of multiple data points. In their 1981 paper, “Graphical Representation of Multivariate Data by Means of Asymmetrical Faces,” statisticians Bernhard Flury and Hans Riedwyl built on Herman Chernoff’s 1973 invention of “Chernoff faces” as a means of displaying and comparing rich, multivariate data for visual analysis.
Because humans can more quickly assess variations in visual, and especially facial, data, the faces provide a quick method to compare degrees of variation between the two text inputs. Since facial expressions also communicate profoundly on a subconscious and emotional level, some facial expressions resulting from data input may be perceived as negative or positive. However, any emotional meanings perceived in the Flury-Riedwyl faces are incidental only to the data inputs, and bear no connection to the emotional tone or voice of the writings or the authors. You can learn more about Graphical Data Representation in faces here.