Adaptation effects to attractiveness of face photographs and art portraits are domain-specific

About the Need for a More Adequate Way to Get an Understanding of the Experiencing of Aesthetic Items

We live in times when neuroscientific methods have become standard methods that many researchers can easily use. While this offers excellent opportunities to understand brain activities linked with aesthetic processing, we face the problem of using sophisticated techniques without a proper and valid theoretical foundation of aesthetics. A further problem arises from sophisticated methods often demanding strict constraints in presenting and experiencing aesthetic stimuli. However, when experiencing aesthetic items, contextual factors matter, e.g., social and situational affordances are essential in triggering a true and deep "Kunsterlebnis" (Experience of Art). Additionally, in Art, it is often not the artwork as an object that matters but the close relationship with and the processing of the artwork. However, art is only one facet of the whole aesthetic domain, beside, e.g., design, architecture, everyday aesthetics, dance, literature, music, and opera. In the present paper, I propose a dynamic and holistic aesthetic perspective that includes the respective context, situation, cognitive and affective traits and state of the beholder, ongoing processes of understanding, Zeitgeist, and other cultural factors, which can be applied to different aesthetic domains. When ignoring such temporal and dynamic factors, we will not understand the qualia of aesthetic processing. These considerations might help researchers in the field of aesthetics to better understand the experiencing of aesthetic items of all kinds-if we ignore these factors, we are missing the essence of experiencing aesthetic items, especially artworks. We aim to sensitize and inform readers about these ideas to inspire a deeper understanding of experiencing aesthetic items and the advancement of a theoretical framework addressing the experiencing of aesthetics from different domains.

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.

Spontaneous recovery of adaptation aftereffects of natural facial categories

Adaptation to a natural face attribute such as a happy face can bias the perception of a subsequent face in this dimension such as a neutral face. Such face adaptation aftereffects have been widely found in many natural facial categories. However, how temporally tuned mechanisms could control the temporal dynamics of natural face adaptation aftereffects remains unknown. To address the question, we used a deadaptation paradigm to examine whether the spontaneous recovery of natural facial aftereffects would emerge in four natural facial categories including variable categories (emotional expressions in Experiment 1 and eye gaze in Experiment 2) and invariable categories (facial gender in Experiment 3 and facial identity in Experiment 4). In the deadaptation paradigm, participants adapted to a face with an extreme attribute (such as a 100% angry face in Experiment 1) for a relatively long duration, and then deadapted to a face with an opposite extreme attribute (such as a 100% happy face in Experiment 1) for a relatively short duration. The time courses of face adaptation aftereffects were measured using a top-up manner. Deadaptation only masked the effects of initial longer-lasting adaptation, and the spontaneous recovery of adaptation aftereffects was observed at the post-test stage for all four natural facial categories. These results likely indicate that the temporal dynamics of adaptation aftereffects of natural facial categories may be controlled by multiple temporally tuned mechanisms.

Edge-Orientation Entropy Predicts Preference for Diverse Types of Man-Made Images

We recently found that luminance edges are more evenly distributed across orientations in large subsets of traditional artworks, i.e., artworks are characterized by a relatively high entropy of edge orientations, when compared to several categories of other (non-art) images. In the present study, we asked whether edge-orientation entropy is associated with aesthetic preference in a wide variety of other man-made visual patterns and scenes. In the first (exploratory) part of the study, participants rated the aesthetic appeal of simple shapes, artificial ornamental patterns, facades of buildings, scenes of interior architecture, and music album covers. Results indicated that edge-orientation entropy predicts aesthetic ratings for these stimuli. However, the magnitude of the effect depended on the type of images analyzed, on the range of entropy values encountered, and on the type of aesthetic rating (pleasing, interesting, or harmonious). For example, edge-orientation entropy predicted about half of the variance when participants rated facade photographs for pleasing and interesting, but only for 3.5% of the variance for harmonious ratings of music album covers. We also asked whether edge-orientation entropy relates to the well-established human preference for curved over angular shapes. Our analysis revealed that edge-orientation entropy was as good or an even better predictor for the aesthetic ratings than curvilinearity. Moreover, entropy could substitute for shape, at least in part, to predict the aesthetic ratings. In the second (experimental) part of this study, we generated complex line stimuli that systematically varied in their edge-orientation entropy and curved/angular shape. Here, edge-orientation entropy was a more powerful predictor for ratings of pleasing and harmonious than curvilinearity, and as good a predictor for interesting. Again, the two image properties shared a large portion of variance between them. In summary, our results indicate that edge-orientation entropy predicts aesthetic ratings in diverse man-made visual stimuli. Moreover, the preference for high edge-orientation entropy shares a large portion of predicted variance with the preference for curved over angular stimuli.

Face Attractiveness versus Artistic Beauty in Art Portraits: A Behavioral Study

From art portraits, the observer may derive at least two different hedonic values: The attractiveness of the depicted person and the artistic beauty of the image that relates to the way of presentation. We argue that attractiveness is a property that is predominantly driven by perceptual processes, while the perception of artistic beauty is based predominantly on cognitive processing. To test this hypothesis, we conducted two behavioral experiments. In a gist study (Experiment 1), we showed that ratings on attractiveness were higher after short-term presentation (50 ms) than after long-term presentation (3000 ms), while the opposite pattern was found for artistic beauty. In an experiment on perceptual contrast (Experiment 2), we showed that the perceptual contrast effect was stronger for attractiveness than for artistic beauty. These results are compatible with our hypothesis that appreciation of artistic beauty is cognitively modulated at least in part, while processing of attractiveness is predominantly driven perceptually. This dichotomy between cognitive and perceptual processing of different kinds of beauty suggests the participation of different neuronal mechanisms.

The Influence of Olfactory Contexts on the Sequential Rating of Odor Pleasantness

When we sequentially evaluate the characteristics of sensory stimuli, our evaluation of a current stimulus is influenced by those preceding it. One such effect is called hedonic contrast, whereby stimuli are rated more negatively (negative contrast) or positively (positive contrast) if they are preceded by more or less pleasant stimuli. The present study investigated the characteristics of hedonic contrast for olfaction and compared these characteristics with those of a more oft-studied modality, vision. The results from two experiments indicated that both positive and negative contrasts occurred in the sequential rating of picture pleasantness, whereas only negative contrast occurred for olfactory ratings. Notably, overrating of hedonically negative odors following a positive olfactory context was observed even when participants had already rated these same negative odors beforehand; conversely, this did not occur for positive contrast for either sense. These findings indicate that negative odors are more strongly influenced than positive ones, and the rating of positive stimuli may be adjusted to the preceding rating independent of stimulus context. The findings of this study revealed the unique characteristics of hedonic contrast for the olfactory senses.

Absence of Sex-Contingent Gaze Direction Aftereffects Suggests a Limit to Contingencies in Face Aftereffects

Face aftereffects (e.g., expression aftereffects) can be simultaneously induced in opposite directions for different face categories (e.g., male and female faces). Such aftereffects are typically interpreted as indicating that distinct neural populations code the categories on which adaptation is contingent, e.g., male and female faces. Moreover, they suggest that these distinct populations selectively respond to variations in the secondary stimulus dimension, e.g., emotional expression. However, contingent aftereffects have now been reported for so many different combinations of face characteristics, that one might question this interpretation. Instead, the selectivity might be generated during the adaptation procedure, for instance as a result of associative learning, and not indicate pre-existing response selectivity in the face perception system. To alleviate this concern, one would need to demonstrate some limit to contingent aftereffects. Here, we report a clear limit, showing that gaze direction aftereffects are not contingent on face sex. We tested 36 young Caucasian adults in a gaze adaptation paradigm. We initially established their ability to discriminate the gaze direction of male and female test faces in a pre-adaptation phase. Afterwards, half of the participants adapted to female faces looking left and male faces looking right, and half adapted to the reverse pairing. We established the effects of this adaptation on the perception of gaze direction in subsequently presented male and female test faces. We found that adaptation induced pronounced gaze direction aftereffects, i.e., participants were biased to perceive small gaze deviations to both the left and right as direct. Importantly, however, aftereffects were identical for male and female test faces, showing that the contingency of face sex and gaze direction participants experienced during the adaptation procedure had no effect.

Combining universal beauty and cultural context in a unifying model of visual aesthetic experience

In this work, I propose a model of visual aesthetic experience that combines formalist and contextual aspects of aesthetics. The model distinguishes between two modes of processing. First, perceptual processing is based on the intrinsic form of an artwork, which may or may not be beautiful. If it is beautiful, a beauty-responsive mechanism is activated in the brain. This bottom-up mechanism is universal amongst humans; it is widespread in the visual brain and responsive across visual modalities. Second, cognitive processing is based on contextual information, such as the depicted content, the intentions of the artist or the circumstances of the presentation of the artwork. Cognitive processing is partially top-down and varies between individuals according to their cultural experience. Processing in the two channels is parallel and largely independent. In the general case, an aesthetic experience is induced if processing in both channels is favorable, i.e., if there is resonance in the perceptual processing channel ("aesthetics of perception"), and successful mastering in the cognitive processing channel ("aesthetics of cognition"). I speculate that this combinatorial mechanism has evolved to mediate social bonding between members of a (cultural) group of people. Primary emotions can be elicited via both channels and modulate the degree of the aesthetic experience. Two special cases are discussed. First, in a subset of (post-)modern art, beauty no longer plays a prominent role. Second, in some forms of abstract art, beautiful form can be enjoyed with minimal cognitive processing. The model is applied to examples of Western art. Finally, implications of the model are discussed. In summary, the proposed model resolves the seeming contradiction between formalist perceptual approaches to aesthetic experience, which are based on the intrinsic beauty of artworks, and contextual approaches, which account for highly individual and culturally dependent aspects of aesthetics.

Cross-category adaptation: exposure to faces produces gender aftereffects in body perception

Prolonged exposure to a stimulus results in a subsequent perceptual bias. This perceptual adaptation aftereffect occurs not only for simple stimulus features but also for high-level stimulus properties (e.g., faces' gender, identity and emotional expressions). Recent studies on aftereffects demonstrate that adaptation to human bodies can modulate face perception because these stimuli share common properties. Those findings suggest that the aftereffect is not related to the physical property of the stimulus but to the great number of semantic attributes shared by the adapter and the test. Here, we report a novel cross-category adaptation paradigm with both silhouette face profiles (Experiment 1.1) and frontal view faces (Experiment 2) as adapters, testing the aftereffects when viewing an androgynous test body. The results indicate that adaptation to both silhouette face profiles and frontal view faces produces gender aftereffects (e.g., after visual exposure to a female face, the androgynous body appears as more male and vice versa). These findings confirm that high-level perceptual aftereffects can occur between cross-categorical stimuli that share common properties.

Attractiveness difference magnitude affected by context, range, and categorization

Previous studies have shown that, when subjects view hedonically positive stimuli followed by stimuli oflesser hedonic value, their preference between the stimuli oflesser hedonic value decreases. This is hedonic condensation. In addition, its opposite, hedonic expansion, occurs when subjects view less hedonically positive stimuli followed by more hedonically positive stimuli. Experiment 1 showed both hedonic condensation and expansion in subjects who viewed pictures of unattractive and moderately attractive faces. Experiment 2 showed that, when subjects were instructed to view the stimuli as coming from two different groups, hedonic expansion but not hedonic condensation was eliminated. Experiment 3 showed that increasing the attractiveness difference between the attractive and unattractive faces eliminated all effects of context on subjects' attractiveness difference judgments. Experiment 4 showed that forcing subjects to categorize the extremely attractive and unattractive faces into the same group resulted in hedonic expansion among attractive faces but not condensation among the unattractive faces. These results suggest that, as hedonic contrast changes the hedonic values of stimuli, it also changes the attention paid to those stimuli, thereby altering the degree of preference between them. Manipulations that prevent a shift in hedonic value also block a shift in the magnitude of the preference judgments.

Beauty in abstract paintings: perceptual contrast and statistical properties

In this study, we combined the behavioral and objective approach in the field of empirical aesthetics. First, we studied the perception of beauty by investigating shifts in evaluation on perceived beauty of abstract artworks (Experiment 1). Because the participants showed heterogeneous individual preferences for the paintings, we divided them into seven clusters for the test. The experiment revealed a clear pattern of perceptual contrast. The perceived beauty of abstract paintings increased after exposure to paintings that were rated as less beautiful, and it decreased after exposure to paintings that were rated as more beautiful. Next, we searched for correlations of beauty ratings and perceptual contrast with statistical properties of abstract artworks (Experiment 2). The participants showed significant preferences for particular image properties. These preferences differed between the clusters of participants. Strikingly, next to color measures like hue, saturation, value and lightness, the recently described Pyramid of Histograms of Orientation Gradients (PHOG) self-similarity value seems to be a predictor for aesthetic appreciation of abstract artworks. We speculate that the shift in evaluation in Experiment 1 was, at least in part, based on low-level adaptation to some of the statistical image properties analyzed in Experiment 2. In conclusion, our findings demonstrate that the perception of beauty in abstract artworks is altered after exposure to beautiful or non-beautiful images and correlates with particular image properties, especially color measures and self-similarity.