Symmetry preference in shapes, faces, flowers and landscapes

Social groups and polarization of aesthetic values from symmetry and complexity

When deciding what images we prefer, our brain must weigh many aesthetic variables, such as symmetry and complexity. To date, aesthetic research has mainly focused on investigating one variable at a time. In this article, we use symmetry and complexity to study the problem of multi aesthetic-variable interactions. For symmetry and complexity, there are two simple interaction hypotheses. The independence hypothesis proposes that the evaluation of aesthetic variables is mutually independent. Meanwhile, Birkhoff's aesthetic-measure hypothesis predicts that people prefer images high in symmetry and low in complexity, and dislike the opposite. To test these hypotheses, we generated images that systematically varied in levels of symmetry and complexity. We then compared the subjects' preference maps to identify regions of likes and dislikes. Unlike the predictions from these hypotheses, we found that most, but not all subjects, formed two distinct natural clusters, termed "islands," in terms of likes and dislikes. We also found that people with more art exposure were less likely to belong to an island. If someone did belong to an island, their gender influenced which cluster they belonged to. We discuss alternate hypotheses, possible mechanisms for the occurrence of islands, and their possible social implications.

Evolution of Human Brain Left-Right Asymmetry: Old Genes with New Functions

The human brain is generally anatomically symmetrical, boasting mirror-like brain regions in the left and right hemispheres. Despite this symmetry, fine-scale structural asymmetries are prevalent and are believed to be responsible for distinct functional divisions within the brain. Prior studies propose that these asymmetric structures are predominantly primate specific or even unique to humans, suggesting that the genes contributing to the structural asymmetry of the human brain might have evolved recently. In our study, we identified approximately 1,500 traits associated with human brain asymmetry by collecting paired brain magnetic resonance imaging features from the UK Biobank. Each trait is measured in a specific region of one hemisphere and mirrored in the corresponding region of the other hemisphere. Conducting genome-wide association studies on these traits, we identified over 1,000 quantitative trait loci. Around these index single nucleotide polymorphisms, we found approximately 200 genes that are enriched in brain-related Gene Ontology terms and are predominantly upregulated in brain tissues. Interestingly, most of these genes are evolutionarily old, originating just prior to the emergence of Bilateria (bilaterally symmetrical animals) and Euteleostomi (bony vertebrates with a brain), at a significantly higher ratio than expected. Further analyses of these genes reveal a brain-specific upregulation in humans relative to other mammalian species. This suggests that the structural asymmetry of the human brain has been shaped by evolutionarily ancient genes that have assumed new functions over time.

I know what i like when i see it: Likability is distinct from pleasantness since early stages of multimodal emotion evaluation

Liking and pleasantness are common concepts in psychological emotion theories and in everyday language related to emotions. Despite obvious similarities between the terms, several empirical and theoretical notions support the idea that pleasantness and liking are cognitively different phenomena, becoming most evident in the context of emotion regulation and art enjoyment. In this study it was investigated whether liking and pleasantness indicate behaviourally measurable differences, not only in the long timespan of emotion regulation, but already within the initial affective responses to visual and auditory stimuli. A cross-modal affective priming protocol was used to assess whether there is a behavioural difference in the response time when providing an affective rating to a liking or pleasantness task. It was hypothesized that the pleasantness task would be faster as it is known to rely on rapid feature detection. Furthermore, an affective priming effect was expected to take place across the sensory modalities and the presentative and non-presentative stimuli. A linear mixed effect analysis indicated a significant priming effect as well as an interaction effect between the auditory and visual sensory modalities and the affective rating tasks of liking and pleasantness: While liking was rated fastest across modalities, it was significantly faster in vision compared to audition. No significant modality dependent differences between the pleasantness ratings were detected. The results demonstrate that liking and pleasantness rating scales refer to separate processes already within the short time scale of one to two seconds. Furthermore, the affective priming effect indicates that an affective information transfer takes place across modalities and the types of stimuli applied. Unlike hypothesized, liking rating took place faster across the modalities. This is interpreted to support emotion theoretical notions where liking and disliking are crucial properties of emotion perception and homeostatic self-referential information, possibly overriding pleasantness-related feature analysis. Conclusively, the findings provide empirical evidence for a conceptual delineation of common affective processes.

Encoding specificity instead of online integration of real-world spatial regularities for objects in working memory

Most objects show high degrees of spatial regularity (e.g. beach umbrellas appear above, not under, beach chairs). The spatial regularities of real-world objects benefit visual working memory (VWM), but the mechanisms behind this spatial regularity effect remain unclear. The "encoding specificity" hypothesis suggests that spatial regularity will enhance the visual encoding process but will not facilitate the integration of information online during VWM maintenance. The "perception-alike" hypothesis suggests that spatial regularity will function in both visual encoding and online integration during VWM maintenance. We investigated whether VWM integrates sequentially presented real-world objects by focusing on the existence of the spatial regularity effect. Throughout five experiments, we manipulated the presentation (simultaneous vs. sequential) and regularity (with vs. without regularity) of memory arrays among pairs of real-world objects. The spatial regularity of memory objects presented simultaneously, but not sequentially, improved VWM performance. We also examined whether memory load, verbal suppression and masking, and memory array duration hindered the spatial regularity effect in sequential presentation. We found a stable absence of the spatial regularity effect, suggesting that the participants were unable to integrate real-world objects based on spatial regularities online. Our results support the encoding specificity hypothesis, wherein the spatial regularity of real-world objects can enhance the efficiency of VWM encoding, but VWM cannot exploit spatial regularity to help organize sampled sequential information into meaningful integrations.

Subjective and Objective Evaluation of the Symmetry of Maxillary Incisors among Residents of Southwest Poland

Dental aesthetics is an essential factor affecting people’s psychosocial wellbeing. One of the most critical components of an aesthetic smile is symmetry within the dentition. Dentists and orthodontists, unlike laypersons, are critical in assessing dental aesthetics. This study aimed to evaluate the accuracy of patients’ assessment of the symmetry of their maxillary incisors and some factors that influence it. The study was conducted on 83 participants aged from 11 to 39 years. First, the participants filled out a questionnaire to obtain patients’ opinions of the symmetry of their upper incisors. This stage was followed by an intraoral examination, during which we used a digital caliper to measure the width of four maxillary incisors. The data were entered into STATISTICA v. 13.3. The following conclusions were drawn from the study. First, the respondents were generally able to determine the asymmetry of the incisors. Second, among the maxillary incisors, the participants defined the symmetry of maxillary central incisors more accurately than the maxillary lateral incisors. The cut-off value for incisor asymmetry noticeable to a layperson is 0.2 mm for maxillary medial incisors and 0.55 for maxillary lateral incisors. Third, we found no dependence of the accuracy of the assessment of incisor asymmetry on the age of the subjects; however, in our study group, the age range (spread) was not significant, so further studies are recommended. Finally, results concerning the relationship with gender showed that males assess the level of symmetry of their maxillary incisors more accurately than females.

Swipes and Saves: A Taxonomy of Factors Influencing Aesthetic Assessments and Perceived Beauty of Mobile Phone Photographs

Digital images taken by mobile phones are the most frequent class of images created today. Due to their omnipresence and the many ways they are encountered, they require a specific focus in research. However, to date, there is no systematic compilation of the various factors that may determine our evaluations of such images, and thus no explanation of how users select and identify relatively “better” or “worse” photos. Here, we propose a theoretical taxonomy of factors influencing the aesthetic appeal of mobile phone photographs. Beyond addressing relatively basic/universal image characteristics, perhaps more related to fast (bottom-up) perceptual processing of an image, we also consider factors involved in the slower (top-down) re-appraisal or deepened aesthetic appreciation of an image. We span this taxonomy across specific types of picture genres commonly taken—portraits of other people, selfies, scenes and food. We also discuss the variety of goals, uses, and contextual aspects of users of mobile phone photography. As a working hypothesis, we propose that two main decisions are often made with mobile phone photographs: (1) Users assess images at a first glance—by swiping through a stack of images—focusing on visual aspects that might be decisive to classify them from “low quality” (too dark, out of focus) to “acceptable” to, in rare cases, “an exceptionally beautiful picture.” (2) Users make more deliberate decisions regarding one’s “favorite” picture or the desire to preserve or share a picture with others, which are presumably tied to aspects such as content, framing, but also culture or personality, which have largely been overlooked in empirical research on perception of photographs. In sum, the present review provides an overview of current focal areas and gaps in research and offers a working foundation for upcoming research on the perception of mobile phone photographs as well as future developments in the fields of image recording and sharing technology.

Perspective Slant Makes Symmetry Harder to Detect and Less Aesthetically Appealing

Abstract symmetric patterns are generally preferred to less regular patterns. Here, we studied 2D patterns presented as 2D images in the plane, and therefore producing a symmetric pattern on the retina, and the same patterns seen in perspective. This perspective transformation eliminates the presence of perfect symmetry in terms of retinotopic coordinates. Stimuli were abstract patterns of local coplanar elements, or irregular polygons. In both cases they can be understood as 2D patterns on a transparent glass pane. In the first study we found that perspective increased reaction time and errors in a classification task, even when the viewing angle was kept constant over many images. In a second study we tested a large sample (148 participants) and asked for a rating of beauty for the same images. In addition, we used the Cognitive Reflection Test (CRT) to test the hypothesis that people who tend to give the more immediate and intuitive answer would also show a stronger preference for the symmetry presented in the frontoparallel plane (in the image and on the retina). Preference for symmetry was confirmed, and there was a cost for perspective viewing. CRT scores were not related to preference, thus not supporting the hypothesis of a stronger preference for symmetry in the image when people follow a more immediate and intuitive gut response.

The Role of Art Expertise and Symmetry on Facial Aesthetic Preferences

Humans, like other species, have a preference for symmetrical visual stimuli, a preference that is influenced by factors such as age, sex, and artistic training. In particular, artistic training seems to decrease the rejection of asymmetry in abstract stimuli. However, it is not known whether the same trend would be observed in relation to concrete stimuli such as human faces. In this article, we investigated the role of expertise in visual arts, music, and dance, in the perceived beauty and attractiveness of human faces with different asymmetries. With this objective, the beauty and attractiveness of 100 photographs of faces with different degrees of asymmetry were evaluated by 116 participants with different levels of art expertise. Expertise in visual arts and dance was associated with the extent to which facial asymmetry influenced the beauty ratings assigned to the faces. The greater the art expertise in visual arts and dance, the more indifferent to facial asymmetry the participant was to evaluate beauty. The same effect was not found for music and neither for attractiveness ratings. These findings are important to help understand how face aesthetic evaluation is modified by artistic training and the difference between beauty and attractiveness evaluations.

Shape familiarity modulates preference for curvature in drawings of common-use objects

Drawing is a way to represent common-use objects. The contour of an object is a salient feature that defines its identity. Preference for a contour (curved or angular) may depend on how familiar the resulting shape looks for that given object. In this research, we examined the influence of shape familiarity on preference for curved or sharp-angled drawings of common-use objects. We also examined the possibility that some individual differences modulated this preference. Preference for curvature was assessed with a liking rating task (Experiment 1) and with a two-alternative forced-choice task simulating approach/avoidance responses (Experiment 2). Shape familiarity was assessed with a familiarity selection task where participants selected the most familiar shape between the curved and the angular version for each object, or whether both shapes were equally familiar for the object. We found a consistent preference for curvature in both experiments. This preference increased when the objects with a curved shape were selected as the most familiar ones. We also found preference for curvature when participants selected the shape of objects as equally familiar. However, there was no preference for curvature or preference for angularity when participants selected the sharp-angled shapes as the most familiar ones. In Experiment 2, holistic and affective types of intuition predicted higher preference for curvature. Conversely, participants with higher scores in the unconventionality facet showed less preference for the curved drawings. We conclude that shape familiarity and individual characteristics modulate preference for curvature.

Normality mediates the effect of symmetry on facial attractiveness

Although symmetry, averageness, and sexual dimorphism are usually considered important to facial attractiveness, there are mixed findings regarding whether and how symmetry influences facial attractiveness. The present study introduced "facial normality" to explain the inconsistency of previous research. We hypothesized that symmetry only increased facial attractiveness when it improved facial normality. We manipulated symmetry and normality simultaneously on sixteen Chinese male faces and asked participants to rate the perceived symmetry, perceived normality, and facial attractiveness. The results demonstrated an interactive effect of symmetry and normality on facial attractiveness. The structural equation model results showed two paths from symmetry to facial attractiveness: (1) Symmetry reduced facial attractiveness by decreasing perceived normality; (2) Symmetry increased facial attractiveness by increasing the perceived symmetry and then improving perceived normality. In other words, perceived normality acted as a mediator between symmetry and facial attractiveness. The present study provides a solution to the different effects of symmetry on facial attractiveness in previous studies and suggests that future studies on symmetry and facial attractiveness should consider the mediating role of normality.

Preferring and Detecting Face Symmetry: Comparing Children and Adults Judging Human and Monkey Faces

Background: Visual symmetry is often found attractive. Symmetry may be preferred either due to a bias in the visual system or due to evolutionary selection pressures related to partner preference. Simple perceptual bias views predict that symmetry preferences should be similar across types of stimuli and unlikely to be related to factors such as age. Methods: The current study examined preferences for symmetry across age groups (pre-puberty vs post-puberty) and stimuli type (human face vs monkey face). Pairs of images manipulated for symmetry were presented and participants asked to choose the image they preferred. Participants repeated the task and were asked to detect symmetry. Results: Both age of observer and stimuli type were associated with symmetry preferences. Older observers had higher preferences for symmetry but preferred it most in human vs monkey stimuli. Across both age groups, symmetry preferences and detection abilities were weakly related. Conclusions: The study supports some ideas from an evolutionary advantage view of symmetry preference, whereby symmetry is expected be higher for potential partners (here human faces) and higher post-puberty when partner choice becomes more relevant. Such potentially motivational based preferences challenge perceptual bias explanations as a sole explanation for symmetry preferences but may occur alongside them.

The extrastriate symmetry response can be elicited by flowers and landscapes as well as abstract shapes

Previous research has investigated the neural response to visual symmetry. It is well established that symmetry activates a network of extrastriate visual regions, including V4 and the Lateral Occipital Complex. This symmetry response generates an event-related potential called the sustained posterior negativity (SPN). However, previous work has used abstract stimuli, typically dot patterns or shapes. We tested the generality of the SPN. We confirmed that the SPN wave was present and of similar amplitude for symmetrical shapes, flowers and landscapes, whether participants were responding either to image symmetry or to image color. We conclude that the extrastriate symmetry response can be generated by any two-dimensional image and is similar in different stimulus domains.

What Experts Appreciate in Patterns: Art Expertise Modulates Preference for Asymmetric and Face-Like Patterns

This study set out to investigate whether and how aesthetic evaluations of different types of symmetric, as well as abstract vs. representational patterns are modulated by art expertise. To this end, we utilized abstract asymmetric, symmetric, and “broken” patterns slightly deviating from symmetry, as well as more representational patterns resembling faces (also symmetric or broken). While it has already been shown that symmetry preference decreases with art expertise, it was still unclear whether an already established relationship between art expertise and preference for abstract over representational art can be similarly found as a preference for abstract over representational patterns, as these are non-art objects. Nevertheless, we found profound differences in aesthetic preferences between art experts and laypersons. While art experts rated asymmetric patterns higher than laypersons, as expected, they rated face-like patterns lower than laypersons. Also, laypersons rated all other types of patterns higher than asymmetric patterns, while art experts rated the other patterns similar or lower than asymmetric patterns. We found this both for liking and for interest ratings. As no differences between art experts and laypersons were found regarding memory recognition of new and old patterns, this effect is not likely due to differences in memory performance. In sum, this study further extends our knowledge about the influence of art expertise on aesthetic appreciation.

The relation between symmetry in food packaging and approach and avoidance words

Research on aesthetic science has demonstrated that people generally prefer symmetrical over asymmetrical compositions. However, it remains unclear whether and how such compositions relate to the concepts of approach and avoidance motivation, especially in consumer contexts. In addition, it is not known how symmetry may influence such concepts in contexts where objects can differ in terms of their hedonic values (symmetry/product taste congruency). In the present research, we evaluated the relation between visual symmetry of the packaging of products with different hedonic value (sweet, non-sweet, non-food) and approach and avoidance words. In two experiments, we found evidence that people associate symmetrical designs with approach words more often than asymmetrical designs. Importantly, however, we did not find evidence that such an effect is influenced by the hedonic value of the products. Our results have value for scholars and practitioners interested in the effect of aesthetic features of brand elements (such as a product's packaging) on consumer motivation.