Tertiary-Expressive Qualities for Design

This chapter deals with tertiary-expressive properties and aims to define, from a Gestalt psychology point of view, the key concepts for design practice.
In the first part of the chapter, a theoretical framework of the tertiary qualities is presented. Starting from Galileo Galilei’s epistemological distinctions between primary and secondary qualities, and the philosophical reflections on the categorization of experienced qualities of Edmund Husserl, I reach the scientific definition of “tertiary qualities” according to Gestalt psychologists. Besides the contributions of Wertheimer, Köhler, and Koffka, Metzger’s theoretical systematization of the “ways of being of qualities” is taken as a major reference, and the conceptual distinction between tertiary qualities, expressive qualities, aufforderungscharakter, and affordances is finally discussed.
The second part of the chapter aims to present the expressive properties in design practice. Two modalities of perceptual communication - the perceptual communication mediated by signs versus the perceptual communication through expressive qualities - are distinguished by means of three antinomies: i) indirect perception versus direct perception, ii) cross reference versus presence, and iii) subjectivity versus universality. Subsequently, it is analyzed how expressiveness is conveyed by single properties (such as shape, size, color, etc.), by objects, and by relationships between objects and their context. In particular, the cases of expressive plurivocal objects (i.e. objects that convey different expressive properties at the same time) are focused. The chapter continues by presenting several design cases with expressive properties in the intermodal and emotional fields, taking as examples both the design of products and communicative artifacts.
In the conclusions, the difference in the use of expressive properties in design and art is discussed.