Abstract
Disciplines as diverse as biology, chemistry, physics, and psychological aesthetics regard symmetry as one of the most important principles in nature and as one of the most powerful determinants of beauty. The influence of symmetry seems so universal (Weyl, 1952) that it has even been discussed as a
Contrary to the high esteem that symmetry has in the sciences, symmetry has a rather low standing in the arts and humanities. For art historians, symmetry is just one of many features used to characterize specific works of art and specific art styles. Art historians, for instance, will state that Classicism has an affinity towards symmetry, whereas Japonism does not. In fact, the 34 volumes of the
The difference in the valuation of symmetry between the two disciplines is a remarkable illustration of the gap between the
It is, however, unclear how this kind of expertise affects aesthetic preferences made quickly and spontaneously, when there is limited opportunity for one’s vast knowledge base to enter the picture. Experts might have a different set of criteria that guide their preferences. If this is indeed the case, it could serve as evidence that the preference for symmetry is not as universal as has been claimed. It could even be that art experts prefer asymmetry.
After close consideration of the above issues, and drawing on knowledge from each of our respective disciplines, we decided to test this hypothesis within an interdisciplinary study, which combined the methodological precision of empirical aesthetics and the theoretical rigor of art history within a straightforward design. The study involved two groups of art experts—artists and art historians—and a group of non-expert participants as a control group. All participants evaluated 160 meaningless, abstract patterns for their beauty. We decided to use such patterns, as they had been used in several behavioral studies that have produced evidence that symmetry is strongly preferred.
The patterns primarily varied along symmetry (symmetrical or asymmetrical) and complexity (simple or complex) dimensions (Jacobsen & Höfel, 2002). Complexity was included as a dimension because previous research has shown that it is related to symmetry—asymmetrical objects are more complex and more demanding to process than their symmetrical counterparts. In addition, people generally prefer complex over simple stimuli. These pattern had been used in several studies with non-art experts and revealed remarkably consistent preferences for symmetry (Gartus & Leder, 2013; Höfel & Jacobsen, 2007; Jacobsen & Höfel, 2002; Tinio, Gerger, & Leder, 2013; Tinio & Leder, 2009).
Method
Participants
A group of 27 art experts (12 advanced students of art from an art academy in Vienna, Austria, and 15 advanced students from the Art History Department of the University of Vienna) and 26 non-art experts (from the Psychology Department of the University of Vienna) were tested in a quasi-experimental design. Informed consent was obtained from each participant prior to data collection, and all participants had normal or corrected-to-normal vision.
Materials and Procedure
The stimuli systematically varied according to symmetry and complexity (40 symmetrical and simple, 40 symmetrical and complex, 40 asymmetrical and simple, and 40 asymmetrical and complex). As in Tinio and Leder (2009), stimuli were derived from the larger, original set by Jacobsen and Höfel (2002). Each stimulus consisted of a solid black circle (8.8 cm in diameter) featuring a centered quadratic rhombic cutout and 86 to 88 basic graphic elements arranged within the rhomb according to a grid and resulting in an abstract pattern. The overall luminance was identical for all stimuli. The basic elements included geometric figures such as triangles, squares, rhombuses, and horizontal, vertical, or oblique bars. A maximum of two mirroring operations giving four possible symmetry axes were permitted. One half of the patterns were symmetrical, while the other half were asymmetrical. Stimulus complexity was manipulated by varying the number of elements composing a pattern (see Jacobsen & Höfel, 2002, for more details).
Participants were tested individually. E-Prime 2.0.8.90 was used to present a fixation cross for 200 ms followed by the stimulus for 3,000 ms on a gray background. The presentation of the stimuli was randomized, and participants rated each stimulus while the stimulus was presented on the screen. Ratings were provided using a 7-point scale with “1” representing
Results
The mean beauty ratings for the stimuli were sampled across participants for each stimulus type (Figure 1). An analysis of variance with

Mean beauty ratings for all conditions and three groups.
In order to demonstrate that the two groups of experts indeed showed a very different pattern of preferences, in Figure 2, we show a depiction of the distribution of the four different types of stimuli (40 stimuli for each type) and their rankings (between 1 and 160) within each of the three groups of participants. Also depicted are the three stimuli judged as most beautiful and the three stimuli judged as least beautiful by each group of participants.

Distribution of ranks of the four different types of stimuli (40 stimuli for each type; between 1 and 160) for each of the three groups of participants.
To show how the different groups of participants differ, in Figure 3, we present three scattergrams of the mean score for each image with art historians on one axis and artists or non-art experts on the other; and likewise for the two groups of experts against each other. This figure clearly shows how much closer (less spread) the preferences are between the two expert groups as compared with the non-experts for whom the means are much higher for the symmetric than the nonsymmetric stimuli.

Scattergrams of means between non-expert ratings for the four classes of stimuli, in relation to the two groups of experts.
We also analyzed the underlying structure of the interindividual differences. We took the standard data matrix of P rows (each being a participant) and S columns (each being a stimulus), transposed it, and then conducted factor analyses (parallel analysis, Monte Carlo, 1,000 iterations), which revealed a three-factor solution. A subsequent principal component analysis (PCA) with direct oblimin rotation (as it allows the data to be orthogonal or oblique depending on the best solution) revealed that the first three components accounted for 47% of the cumulative variance. Mostly non-expert participants loaded positively and all experts loaded negatively on the first factor (approximately 30% of the variance). A few non-experts loaded on Factors 2 and 3 (approximately 10% of the variance).
We also conducted an analysis of variance in which we included the three factors revealed by the PCA as levels of the independent variable, and an index (for each participant) of preference for symmetry—mean liking of symmetry minus mean preference for asymmetry; mean values were Factor 1 (
The results indicate that people untrained in the visual arts did show the often-claimed preference for symmetrical and complex stimuli. In contrast, experts seemed to completely disregard these design principles and showed stronger and more consistent preferences for stimuli that deviated from symmetry. The experts also showed more variability in their preference for complexity. Future studies must, however, determine the level of processing within which such differences are manifested, although the present results illustrate what could result from the convergence of art and science.
General Discussion
The results showed that non-art experts evaluated the symmetrical–complex stimuli as most beautiful, followed in descending order by symmetrical–simple, asymmetrical–complex, and asymmetrical–simple stimuli. This was an expected pattern of responses that has been previously shown to be largely stable, that is for non-art expert participants. What was surprising, however, was that both groups of experts showed a contrasting, even reversed, pattern of responses: Unlike the non-art experts who found symmetrical and complex stimuli to be most beautiful, the art experts found asymmetrical and simple stimuli to be most beautiful. The results are depicted in Figure 2 where each color-coded bar represents one type of stimulus. The distribution of the bars reflects the average set of
Although we did not find any statistically significant difference between the two groups of experts—artists and art historians—the stimuli judged as most beautiful shown in Figure 2 suggest that when art historians look at the stimuli, they could have thought of them as constructivist abstractions—such as those by Malevich or Mondrian. Artists did not show this bias. Post hoc questions given to the experts, that were included as a check on expertise indeed revealed their status of experience and interest in art. However, only two experts (one art historian and one artist) mentioned that the pattern reminded them of artworks, or artists, without being more specific. Therefore, this explanation of specific art associations could be tested further in future studies and would provide evidence for the influence of specific education and training within the arts (e.g., education in art history vs. art making).
Future studies might also more systematically study different kinds of symmetry and test more specificly whether different participants prefer different kinds of symmetry. Moreover, current methods in quantifying symmetry might help to identify even finer grades of preferences for symmetry and its relation to other image properties (al-Rifaie et al., 2017). Also, in order to better understand differences between experts and non-experts, a much broader approach could combine various perceptual tasks with a battery of personality measures (see McManus, 2006).
Our results demonstrate that the gap between the two cultures—art and science—in terms of the evaluation of symmetry corresponds to, and might be rooted in, basic differences in aesthetic responses. Those differences could be the result of extensive training (or lack thereof) in the arts (see Belke, Leder, Harsanyi, & Carbon, 2010). In the present study, to test our expertise-related hypotheses in a straightforward research design, we used meaningless patterns that had no biological or artistic significance. In a recent study, Little (2014) had shown that there are different levels of preferences for different classes of object. He found that symmetry preferences were much weaker for artworks as compared to faces. An interesting issue to test in future studies is whether the use of symmetry in artworks for experts would show similar results.
Symmetry is often considered as the most fundamental of aesthetic primitives. Now, the assumed biologically hard-wired response to symmetry has to be put into perspective. Altogether, these results challenge the concept of universal aesthetic principles and demand more in-depth examination of how factors—such as knowledge, expertise, culture, and context—influence the aesthetic perception of our world.
