Order in complexity: How Hans Eysenck brought differential psychology and aesthetics together

Although Hans Eysenck's reputation is for the most part related to other works, empirical aesthetics was the topic of his PhD, a field in which he remained interested for a very long time, steering the domain's wheel towards the study of individual differences. In this article, we review his work and impact in the field. We first argue that his works on aesthetics demonstrate his interest for natural sciences and arts, his gestaltist views on art and psychology, as well as the influence of Burt and of his first wife, Margaret Davies, on his work. We then analyze his first factor analytic works on aesthetic preferences, leading to the discovery of the two factors of aesthetic judgment - 'T' (for taste) and 'K' (for appreciation of complexity) - and show how, in spite of his impact in other fields, he kept demonstrating concern for the measure and determinants of these two factors. Finally, we discuss the extensions and limitations of Eysenck's contribution to the field of empirical aesthetics, proposing that the 'T-K' duality sowed important seeds for a unified concept of 'Aesthetic Quotient'.