Ambiguities and conventions in the perception of visual art

Database of Expressionist, Impressionist, and Post-Impressionist paintings: Affective norms for 60 art pieces

Modern painters' art is not only different from canvas created earlier, but also shows high internal variability. Being aware of the conditions arising from art history, we used paintings from three art movements-Impressionism, Post-Impressionism, and Expressionism, to see if we are able to respond to claims made by art theorists by using methods specific to social sciences, and validate the paintings as stimuli which might evoke different emotional reaction based on the movement they were created in. We wanted to conduct an exploratory analysis comparing the mean assessment of valence, arousal, and dominance among the three art movements. A total of 60 different paintings were selected (20 for each art movement) showing figurative works and visible human figures. They were assessed on five different affective scales: valence, arousal, dominance, origin, and subjective significance with use of Self-Assessment Manikins. The results showed expected differences in affective reactions to Expressionist paintings compared with those of Impressionist and Post-Impressionist ones. Therefore, we provided the very first dataset of emotional stimuli with validated affective norms, categorised by the art movement that they were created in and ready to be used in future experimental studies.

A hole in a piece of cardboard and predictive brain: the incomprehension of modern art in the light of the predictive coding paradigm

Incomprehension of and resistance to contemporaneous art have been constant features in the development of modern art. The predictive coding framework can be used to analyse this response by outlining the difference between the misunderstanding of (i) contemporary conceptual/minimalist art and (ii) early modern avant-garde art and by elucidating their underlying cognitive mechanisms. In both of these cases, incomprehension and its behavioural consequences are tied to the failure of the optimal prediction error (PE) minimization that is involved in the perception of such art works. In the case of contemporary conceptual/minimalist art the failure stems from the fact that the encounter results in non-salient visual sensations and generates no PE. In early modern avant-garde art, the occasional inability of viewers to recognize pictorial content using new pictorial conventions reflected the absence of suitable priors to explain away ambiguous sensory data. The capacity to recognize pictorial content in modernist painting, as a prerequisite for a satisfying encounter with such works and ultimately a wider acceptance of new artistic styles, required an updating of a number of expectations in order to optimize the fit between priors and sensations, from low-level perceptual priors to the development of higher-level, culturally determined expectations. This article is part of the theme issue 'Art, aesthetics and predictive processing: theoretical and empirical perspectives'.

Time-of-day perception in paintings

The spectral shape, irradiance, direction, and diffuseness of daylight vary regularly throughout the day. The variations in illumination and their effect on the light reflected from objects may in turn provide visual information as to the time of day. We suggest that artists' color choices for paintings of outdoor scenes might convey this information and that therefore the time of day might be decoded from the colors of paintings. Here we investigate whether human viewers' estimates of the depicted time of day in paintings correlate with their image statistics, specifically chromaticity and luminance variations. We tested time-of-day perception in 17th- to 20th-century Western European paintings via two online rating experiments. In Experiment 1, viewers' ratings from seven time choices varied significantly and largely consistently across paintings but with some ambiguity between morning and evening depictions. Analysis of the relationship between image statistics and ratings revealed correlations with the perceived time of day: higher "morningness" ratings associated with higher brightness, contrast, and saturation and darker yellow/brighter blue hues; "eveningness" with lower brightness, contrast, and saturation and darker blue/brighter yellow hues. Multiple linear regressions of extracted principal components yielded a predictive model that explained 76% of the variance in time-of-day perception. In Experiment 2, viewers rated paintings as morning or evening only; rating distributions differed significantly across paintings, and image statistics predicted people's perceptions. These results suggest that artists used different color palettes and patterns to depict different times of day, and the human visual system holds consistent assumptions about the variation of natural light depicted in paintings.

Changing What You Like: Modifying Contour Properties Shifts Aesthetic Valuations of Scenes

To what extent do aesthetic experiences arise from the human ability to perceive and extract meaning from visual features? Ordinary scenes, such as a beach sunset, can elicit a sense of beauty in most observers. Although it appears that aesthetic responses can be shared among humans, little is known about the cognitive mechanisms that underlie this phenomenon. We developed a contour model of aesthetics that assigns values to visual properties in scenes, allowing us to predict aesthetic responses in adults from around the world. Through a series of experiments, we manipulate contours to increase or decrease aesthetic value while preserving scene semantic identity. Contour manipulations directly shift subjective aesthetic judgments. This provides the first experimental evidence for a causal relationship between contour properties and aesthetic valuation. Our findings support the notion that visual regularities underlie the human capacity to derive pleasure from visual information.

Art Value Creation and Destruction

I present a theory of creative and destructive value state referring to abstract art. Value is a probabilistic state held as a mixture of its expectation and information forces that coexist in a give-and-take relationship. Expectations are driven by the disclosure of novel information about the value state of various events of desire. Each bit of accumulated information contributes to the improvement of perception up to a threshold level, beyond which begin conscious states. The desire to disclose a value state triggers a triadic system of evaluation which uses concepts, observables and approaches. While the triadic valuation mechanisms can be used to assess various commodities, the scope of this work is limited to the case of artworks, in particular abstract paintings. I assume that art value is basically mediated by the interplay between these value state mechanisms of creation and destruction. Expectations in artwork develop attraction by challenging its contemplator to evaluate (predict) its meaning. Once the relevant information, corresponding to its creative expectations, is acquired (and conditioned), emotional states of indifference, disinterest and desensitization develop.

Do we enjoy what we sense and perceive? A dissociation between aesthetic appreciation and basic perception of environmental objects or events

This integrative review rearticulates the notion of human aesthetics by critically appraising the conventional definitions, offerring a new, more comprehensive definition, and identifying the fundamental components associated with it. It intends to advance holistic understanding of the notion by differentiating aesthetic perception from basic perceptual recognition, and by characterizing these concepts from the perspective of information processing in both visual and nonvisual modalities. To this end, we analyze the dissociative nature of information processing in the brain, introducing a novel local-global integrative model that differentiates aesthetic processing from basic perceptual processing. This model builds on the current state of the art in visual aesthetics as well as newer propositions about nonvisual aesthetics. This model comprises two analytic channels: aesthetics-only channel and perception-to-aesthetics channel. The aesthetics-only channel primarily involves restricted local processing for quality or richness (e.g., attractiveness, beauty/prettiness, elegance, sublimeness, catchiness, hedonic value) analysis, whereas the perception-to-aesthetics channel involves global/extended local processing for basic feature analysis, followed by restricted local processing for quality or richness analysis. We contend that aesthetic processing operates independently of basic perceptual processing, but not independently of cognitive processing. We further conjecture that there might be a common faculty, labeled as aesthetic cognition faculty, in the human brain for all sensory aesthetics albeit other parts of the brain can also be activated because of basic sensory processing prior to aesthetic processing, particularly during the operation of the second channel. This generalized model can account not only for simple and pure aesthetic experiences but for partial and complex aesthetic experiences as well.

Universality and superiority in preference for chromatic composition of art paintings

Color composition in paintings is a critical factor affecting observers’ aesthetic judgments. We examined observers’ preferences for the color composition of Japanese and Occidental paintings when their color gamut was rotated. In the experiment, observers were asked to select their preferred image from original and three hue-rotated images in a four-alternative forced choice paradigm. Despite observers’ being unfamiliar with the presented artwork, the original paintings (0 degrees) were preferred more frequently than the hue-rotated ones. Furthermore, the original paintings’ superiority was observed when the images were divided into small square pieces and their positions randomized (Scrambled condition), and when the images were composed of square pieces collected from different art paintings and composed as patchwork images (Patchwork condition). Therefore, the original paintings’ superiority regarding preference was quite robust, and the specific objects in the paintings associated with a particular color played only a limited role. Rather, the original paintings’ general trend in color statistics influenced hue-angle preference. Art paintings likely share common statistical regulations in color distributions, which may be the basis for the universality and superiority of the preference for original paintings.

Fostering the Aesthetic Pleasure: The Effect of Verbal Description on Aesthetic Appreciation of Ambiguous and Unambiguous Artworks

Background: Aesthetic experience begins through an intentional shift from automatic visual perceptual processing to an aesthetic state of mind that is evidently directed towards sensory experience. In the present study, we investigated whether portrait descriptions affect the aesthetic pleasure of both ambiguous (i.e., Arcimboldo’s portraits) and unambiguous portraits (i.e., Renaissance portraits). Method: A total sample of 86 participants were recruited and completed both a baseline and a retest session. In the retest session, we implemented a sample audio description for each portrait. The portraits were described by three types of treatment, namely global, local, and historical descriptions. Results: During the retest session, aesthetic pleasure was higher than the baseline. Both the local and the historical treatments improved the aesthetic appreciation of ambiguous portraits; instead, the global and the historical treatment improved aesthetic appreciation of Renaissance portraits during the retest session. Additionally, we found that the response times were slower in the retest session. Conclusion: taken together, these findings suggest that aesthetic preference was affected by the description of an artwork, likely due to a better knowledge of the painting, which prompts a more accurate (and slower) reading of the artwork.

If painters give you lemons, squeeze the knowledge out of them. A study on the visual perception of the translucent and juicy appearance of citrus fruits in paintings

Citrus fruits are characterized by a juicy and translucent interior, important properties that drive material recognition and food acceptance. Yet, a thorough understanding of their visual perception is still missing. Using citrus fruits depicted in 17th-century paintings as stimuli, we ran three rating experiments. In Experiment 1, participants rated the perceived similarity in translucency or juiciness of the fruits. In Experiment 2, different groups of participants rated one image feature from a list obtained in a preliminary experiment. In Experiment 3, translucency and juiciness were rated. We constructed two-dimensional perceptual spaces for both material properties and fitted the ratings of the image features into the spaces to interpret them. “Highlights,” “peeled side,” “bumpiness,” and “color saturation” fit the juiciness space best and were high for the highly juicy stimuli. “Peeled side,” “intensity of light gradient,” “highlights,” and “color saturation” were the most salient features of the translucency space, being high for the highly translucent stimuli. The same image features were also indicated in a 17th-century painting manual for material depiction (Beurs, 1692; Beurs, in press). Altogether, we disclosed the expertise of painters with regard to material perception by identifying the image features that trigger a visual impression of juiciness and translucency in citrus fruits.

A deep-learning framework for human perception of abstract art composition

Artistic composition (the structural organization of pictorial elements) is often characterized by some basic rules and heuristics, but art history does not offer quantitative tools for segmenting individual elements, measuring their interactions and related operations. To discover whether a metric description of this kind is even possible, we exploit a deep-learning algorithm that attempts to capture the perceptual mechanism underlying composition in humans. We rely on a robust behavioral marker with known relevance to higher-level vision: orientation judgements, that is, telling whether a painting is hung “right-side up.” Humans can perform this task, even for abstract paintings. To account for this finding, existing models rely on “meaningful” content or specific image statistics, often in accordance with explicit rules from art theory. Our approach does not commit to any such assumptions/schemes, yet it outperforms previous models and for a larger database, encompassing a wide range of painting styles. Moreover, our model correctly reproduces human performance across several measurements from a new web-based experiment designed to test whole paintings, as well as painting fragments matched to the receptive-field size of different depths in the model. By exploiting this approach, we show that our deep learning model captures relevant characteristics of human orientation perception across styles and granularities. Interestingly, the more abstract the painting, the more our model relies on extended spatial integration of cues, a property supported by deeper layers.

Confidence Forced-Choice and Other Metaperceptual Tasks

Metaperception is the self-monitoring and self-control of one's own perception. Perceptual confidence is the prototypical example of metaperception. Perceptual confidence refers to the ability to judge whether a perceptual decision is correct. We argue that metaperception is not limited to confidence but includes other judgments such as the estimation of familiarity and the aesthetic experience of sensory events. Perceptual confidence has recently received a surge of interests due in particular to the design of careful psychophysical experiments and powerful computational models. In psychophysics, the use of confidence ratings is the dominant methodology, but other paradigms are available, including the confidence forced choice. In this latter paradigm, participants are presented with two stimuli, make perceptual decisions about these stimuli, and then choose which decision is more likely to be correct. One benefit of confidence forced choice is that it disregards confidence biases to focus on confidence sensitivity. Confidence forced choice might also be a paradigm that will allow us to establish whether confidence is estimated serially or in parallel to the perceptual decision.

Cartographic Design of Cultural Maps

Throughout history, maps have been used as a tool to explore cities. They visualize a city's urban fabric through its streets, buildings, and points of interest. Besides purely navigation purposes, street names also reflect a city's culture through its commemorative practices. Therefore, cultural maps that unveil socio-cultural characteristics encoded in street names could potentially raise citizens' historical awareness. But designing effective cultural maps is challenging, not only due to data scarcity but also due to the lack of effective approaches to engage citizens with data exploration. To address these challenges, we collected a dataset of 5000 streets across the cities of Paris, Vienna, London, and New York, and built their cultural maps grounded on cartographic storytelling techniques. Through data exploration scenarios, we demonstrated how cultural maps engage users and allow them to discover distinct patterns in the ways these cities are gender-biased, celebrate various professions, and embrace foreign cultures.

Light: Toward a Transdisciplinary Science of Appearance and Atmosphere

To understand the processes behind seeing light, we need to integrate knowledge about the incoming optical structure, its perception, and how light interacts with material, shape, and space-objectively and subjectively. To that end, we need a novel approach to the science of light, namely, a transdisciplinary science of appearance, integrating optical, perceptual, and design knowledge and methods. In this article, I review existing literature as a basis for such a synthesis, which should discuss light in its full complexity, including its spatial properties and interactions with materials, shape, and space. I propose to investigate this by representing the endless variety of light, materials, shapes, and space as canonical modes and their combinations.

Kandinsky or Me? How Free Is the Eye of the Beholder in Abstract Art?

We investigated in "art-naïve" German and Chinese participants the perception of color and spatial balance in abstract art. For color perception, we asked participants (a) to adjust the color of a single element in 24 paintings according to their liking and (b) to indicate whether they preferred their version of the painting or the original. For spatial perception, we asked participants (a) to determine the "balance point" of an artwork and (b) to indicate their preferences for the original or left-right reversed orientation of previously seen and unfamiliar paintings. Results of the color experiments suggest that, even though the interactive task was of a rather open-ended nature, observers' color adjustments were not random but systematically influenced by each painting's color palette. Overall, participants liked their own color choices about as much as the original composition. Results of the spatial experiments reveal a remarkable consistency between participants in their balance point settings. The perceived lateral position of the balance point systematically affected the left-right orientation preference for a given painting. We conclude that "art-naïve" observers are sensitive to the composition of colors and spatial structures in abstract art and are influenced by their cultural backgrounds when experiencing abstract paintings.

Understanding gloss perception through the lens of art: Combining perception, image analysis, and painting recipes of 17th century painted grapes

To understand the key image features that we use to infer the glossiness of materials, we analyzed the pictorial shortcuts used by 17th century painters to imitate the optical phenomenon of specular reflections when depicting grapes. Gloss perception of painted grapes was determined via a rating experiment. We computed the contrast, blurriness, and coverage of the grapes' highlights in the paintings' images, inspired by Marlow and Anderson (2013). The highlights were manually segmented from the images, and next the features contrast, coverage, and blurriness were semiautomatically quantified using self-defined algorithms. Multiple linear regressions of contrast and blurriness resulted in a predictive model that could explain 69% of the variance in gloss perception. No effect was found for coverage. These findings are in agreement with the instructions to render glossiness of grapes contained in a 17th century painting manual (Beurs, 1692/in press), suggesting that painting practice embeds knowledge about key image features that trigger specific material percepts.

Reliable Top-Left Light Convention Starts With Early Renaissance: An Extensive Approach Comprising 10k Artworks

Art history claims that Western art shows light from the top left, which has been repeatedly shown with narrow image sets and simplistic research methods. Here we employed a set of 10,000 pictures for which participants estimated the direction of light plus their confidence of estimation. From 1420 A.D., the onset of Early Renaissance, until 1900 A.D., we revealed a clear preference for painting light from the top left—within the same period, we observed the highest confidence in such estimations of the light source.

Can people identify original and manipulated photos of real-world scenes?

Advances in digital technology mean that the creation of visually compelling photographic fakes is growing at an incredible speed. The prevalence of manipulated photos in our everyday lives invites an important, yet largely unanswered, question: Can people detect photo forgeries? Previous research using simple computer-generated stimuli suggests people are poor at detecting geometrical inconsistencies within a scene. We do not know, however, whether such limitations also apply to real-world scenes that contain common properties that the human visual system is attuned to processing. In two experiments we asked people to detect and locate manipulations within images of real-world scenes. Subjects demonstrated a limited ability to detect original and manipulated images. Furthermore, across both experiments, even when subjects correctly detected manipulated images, they were often unable to locate the manipulation. People’s ability to detect manipulated images was positively correlated with the extent of disruption to the underlying structure of the pixels in the photo. We also explored whether manipulation type and individual differences were associated with people’s ability to identify manipulations. Taken together, our findings show, for the first time, that people have poor ability to identify whether a real-world image is original or has been manipulated. The results have implications for professionals working with digital images in legal, media, and other domains.

Objects Versus Shadows as Influences on Perceived Object Motion

The motion trajectory of an object’s cast shadow has been shown to alter the perceived trajectory of a casting object, an effect that holds even if the cast shadow appears unrealistic. This raises the question of whether a cast shadow per se is necessary for this influence, a question that has been studied only with stationary targets. We examined the relative influence of a shadow and a spherical object on the perceived motion trajectory of an identical spherical object, using a paradigm similar to Kersten, Mamassian, and Knill's ball-in-box animation. We recorded both depth and height estimates of the perceived end-point of the target trajectory as a function of various target and context trajectories. Both shadows and objects significantly influenced the perceived trajectory of the target, though the influence of the shadow was overall stronger. We conjecture that the influence of the object reveals the assumption that similar objects moving at the same speed and in similar directions are perceived to move within the same plane, a plane subject to a fronto-parallel bias.

The colors of paintings and viewers' preferences

One hypothesis to explain the aesthetics of paintings is that it depends on the extent to which they mimic natural image statistics. In fact, paintings and natural scenes share several statistical image regularities but the colors of paintings seem generally more biased towards red than natural scenes. Is the particular option for colors in each painting, even if less naturalistic, critical for perceived beauty? Here we show that it is. In the experiments, 50 naïve observers, unfamiliar with the 10 paintings tested, could rotate the color gamut of the paintings and select the one producing the best subjective impression. The distributions of angles obtained are described by normal distributions with maxima deviating, on average, only 7 degrees from the original gamut orientation and full width at half maximum just above the threshold to perceive a chromatic change in the paintings. Crucially, for data pooled across observers and abstract paintings the maximum of the distribution was at zero degrees, i.e., the same as the original. This demonstrates that artists know what chromatic compositions match viewers' preferences and that the option for less naturalistic colors does not constrain the aesthetic value of paintings.

Statistics of colors in paintings and natural scenes

Painters reproduce some spatial statistical regularities of natural scenes. To what extent they replicate their color statistics is an open question. We investigated this question by analyzing the colors of 50 natural scenes of rural and urban environments and 44 paintings with abstract and figurative compositions. The analysis was carried out using hyperspectral imaging data from both sets and focused on the gamut and distribution of colors in the CIELAB space. The results showed that paintings, like natural scenes, have gamuts with elongated shapes in the yellow-blue direction but more tilted to the red direction. It was also found that the fraction of discernible colors, expressed as a function of the number of occurrences in the scene or painting, is well described by power laws. These have similar distribution of slopes in a log-log scale for paintings and natural scenes. These features are observed in both abstract and figurative compositions. These results suggest that the underlying chromatic structure of artistic compositions generally follows the main statistical features of the natural environment.

When Challenging Art Gets Liked: Evidences for a Dual Preference Formation Process for Fluent and Non-Fluent Portraits

Although fluency theory predominates psychological research on human aesthetics, its most severe limitation may be to explain why art that challenges or even violates easy processing can nevertheless be aesthetically rewarding. We discuss long-standing notions on art's potential to offer mental growth opportunities and to tap into a basic epistemic predisposition that hint at a fluency counteracting aesthetic pleasure mechanism. Based on divergent strands of literature on empirical, evolutionary, and philosophical aesthetics, as well as research on disfluency, we presumed that challenging art requires deliberate reflexive processing at the level of "aboutness" in order to be experientially pleasing. Here, we probed such a cognitive mastering mechanism, achieved by iterative cycles of elaboration, as predicted by our model of aesthetic experiences. For the study, two kinds of portraits were applied, one associable to a high fluency and one to a high stimulation potential (according to results of an extensive rating study). In Experiment 1, we provided a repeated evaluation task, which revealed a distinctive preference effect for challenging portraits that was absent in the visual exposition conditions of a familiarity and a mere exposure task (Experiment 2). In a follow-up task (Experiment 3) this preference effect was observed with a novel and more encompassing pool of portraits, which corroborated its stability and robustness. In an explorative stimulus-transfer task (Experiment 4), we investigated the presumed underlying mechanism by testing whether the observed effect would generalize onto novel portraits of the same artist-specific styles. Results discounted an alternative interpretation of a perceptual adaptation effect and hinted at meaning-driven mental activity. Conjointly, findings for inexperienced viewers were indicative of an elaboration based mastering mechanism that selectively operated for mentally challenging portraits. Moreover, findings were in line with a dual-process view of human preference formation with art. Theoretical implications and boundary conditions are discussed.

Do you like Arcimboldo's? Esthetic appreciation modulates brain activity in solving perceptual ambiguity

Esthetic experience is a unique, affectively colored, self-transcending subject-object relationship in which cognitive processing is felt to flow differently than during everyday experiences. Notwithstanding previous multidisciplinary investigations, how esthetic experience modulates perception is still obscure. We used Arcimboldo's ambiguous portraits to assess how the esthetic context organizes ambiguous percepts. The study was carried out using functional magnetic resonance imaging (fMRI) in healthy young volunteers (mean age 25.45; S.D. 4.51; 9 females), during both an explicit esthetic judgment task and an artwork/non-artwork classification task. We show that a distinct neural mechanism in the fusiform gyrus contributes to the esthetic experience of ambiguous portraits, according to the valence of the esthetic experience. Ambiguous artworks eliciting a negative esthetic experience lead to more pronounced activation of the fusiform face areas than ambiguous artworks eliciting a positive esthetic experience. We also found an interaction between task and ambiguity in the right superior parietal lobule. Taken together, our results demonstrate that a neural mechanism in the content-dependent brain regions of face processing underlies the esthetic experience of ambiguous portraits. Furthermore, they suggest that esthetic experience interacts with perceptual qualities of stimuli in the right superior parietal lobe, supporting the idea that esthetic experience arises from the interaction between top-down orienting of attention and bottom-up perceptual facilitation.

Is this a "Fettecke" or just a "greasy corner"? About the capability of laypersons to differentiate between art and non-art via object's originality

Which components are needed to identify an object as an artwork, particularly if it is contemporary art? A variety of factors determining aesthetic judgements have been identified, among them stimulus-related properties such as symmetry, complexity and style, but also person-centred as well as context-dependent variables. We were particularly interested in finding out whether laypersons are at all able to distinguish between pieces of fine art endorsed by museums and works not displayed by galleries and museums. We were also interested in analysing the variables responsible for distinguishing between different levels of artistic quality. We ask untrained (Exp.1) as well as art-trained (Exp.2) people to rate a pool of images comprising contemporary art plus unaccredited objects with regard to preference, originality, ambiguity, understanding and artistic quality. Originality and ambiguity proved to be the best predictor for artistic quality. As the concept of originality is tightly linked with innovativeness, a property known to be appreciated only by further, and deep, elaboration (Carbon, 2011i-Perception, 2, 708–719), it makes sense that modern artworks might be cognitively qualified as being of high artistic quality but are meanwhile affectively devaluated or even rejected by typical laypersons—at least at first glance.

Image ambiguity and fluency

Ambiguity is often associated with negative affective responses, and enjoying ambiguity seems restricted to only a few situations, such as experiencing art. Nevertheless, theories of judgment formation, especially the “processing fluency account”, suggest that easy-to-process (non-ambiguous) stimuli are processed faster and are therefore preferred to (ambiguous) stimuli, which are hard to process. In a series of six experiments, we investigated these contrasting approaches by manipulating fluency (presentation duration: 10ms, 50ms, 100ms, 500ms, 1000ms) and testing effects of ambiguity (ambiguous versus non-ambiguous pictures of paintings) on classification performance (Part A; speed and accuracy) and aesthetic appreciation (Part B; liking and interest). As indicated by signal detection analyses, classification accuracy increased with presentation duration (Exp. 1a), but we found no effects of ambiguity on classification speed (Exp. 1b). Fifty percent of the participants were able to successfully classify ambiguous content at a presentation duration of 100 ms, and at 500ms even 75% performed above chance level. Ambiguous artworks were found more interesting (in conditions 50ms to 1000ms) and were preferred over non-ambiguous stimuli at 500ms and 1000ms (Exp. 2a - 2c, 3). Importantly, ambiguous images were nonetheless rated significantly harder to process as non-ambiguous images. These results suggest that ambiguity is an essential ingredient in art appreciation even though or maybe because it is harder to process.

Attractiveness is influenced by the relationship between postures of the viewer and the viewed person

Many factors influence physical attractiveness, including degree of symmetry and relative length of legs. We asked a sample of 112 young adults to rate the attractiveness of computer-generated female bodies that varied in terms of symmetry and leg-to-body ratio. These effects were confirmed. However, we also varied whether the person in the image was shown sitting or standing. Half of the participants were tested standing and the other half sitting. The difference in the posture of the participants increased the perceived attractiveness of the images sharing the same posture, despite the fact that participants were unaware that their posture was relevant for the experiment. We conclude that our findings extend the role of embodied simulation in social cognition to perception of attractiveness from static images.

Self-portraits: smartphones reveal a side bias in non-artists

According to surveys of art books and exhibitions, artists prefer poses showing the left side of the face when composing a portrait and the right side when composing a self-portrait. However, it is presently not known whether similar biases can be observed in individuals that lack formal artistic training. We collected self-portraits by naïve photographers who used the iPhone™ front camera, and confirmed a right side bias in this non-artist sample and even when biomechanical constraints would have favored the opposite. This result undermines explanations based on posing conventions due to artistic training or biomechanical factors, and is consistent with the hypothesis that side biases in portraiture and self-portraiture are caused by biologically- determined asymmetries in facial expressiveness.

Putting reward in art: A tentative prediction error account of visual art

The predictive coding model is increasingly and fruitfully used to explain a wide range of findings in perception. Here we discuss the potential of this model in explaining the mechanisms underlying aesthetic experiences. Traditionally art appreciation has been associated with concepts such as harmony, perceptual fluency, and the so-called good Gestalt. We observe that more often than not great artworks blatantly violate these characteristics. Using the concept of prediction error from the predictive coding approach, we attempt to resolve this contradiction. We argue that artists often destroy predictions that they have first carefully built up in their viewers, and thus highlight the importance of negative affect in aesthetic experience. However, the viewer often succeeds in recovering the predictable pattern, sometimes on a different level. The ensuing rewarding effect is derived from this transition from a state of uncertainty to a state of increased predictability. We illustrate our account with several example paintings and with a discussion of art movements and individual differences in preference. On a more fundamental level, our theorizing leads us to consider the affective implications of prediction confirmation and violation. We compare our proposal to other influential theories on aesthetics and explore its advantages and limitations.

The effect of left-right reversal on film: Watching Kurosawa reversed

The mirror reversal of an image is subtly different from the original. Often such change goes unnoticed in pictures, although it can affect preference. For the first time we studied the effect of mirror reversal of feature films. People watched Yojimbo or Sanjuro in a cinema, both classic films by Akira Kurosawa. They knew that this was a study and filled out a questionnaire. On one day Yojimbo was shown in its original orientation, and on another day the film was mirror reversed. Sanjuro was shown reversed on one day and non-reversed on another day. Viewers did not notice the reversal, even when they had seen the film before and considered themselves fans of Kurosawa. We compared this with estimates from a survey. In addition, the question about the use of space (scenography) revealed that although people who had seen the film before gave higher ratings compared with those who had not, this was only true when the film was not reversed.

The neural time course of art perception: an ERP study on the processing of style versus content in art

A central prerequisite to understand the phenomenon of art in psychological terms is to investigate the nature of the underlying perceptual and cognitive processes. Building on a study by Augustin, Leder, Hutzler, and Carbon (2008) the current ERP study examined the neural time course of two central aspects of representational art, one of which is closely related to object- and scene perception, the other of which is art-specific: content and style. We adapted a paradigm that has repeatedly been employed in psycholinguistics and that allows one to examine the neural time course of two processes in terms of when sufficient information is available to allow successful classification. Twenty-two participants viewed pictures that systematically varied in style and content and conducted a combined go/nogo dual choice task. The dependent variables of interest were the Lateralised Readiness Potential (LRP) and the N200 effect. Analyses of both measures support the notion that in the processing of art style follows content, with style-related information being available at around 224 ms or between 40 and 94 ms later than content-related information. The paradigm used here offers a promising approach to further explore the time course of art perception, thus helping to unravel the perceptual and cognitive processes that underlie the phenomenon of art and the fascination it exerts.

Prior knowledge of illumination for 3D perception in the human brain

In perceiving 3D shape from ambiguous shading patterns, humans use the prior knowledge that the light is located above their head and slightly to the left. Although this observation has fascinated scientists and artists for a long time, the neural basis of this "light from above left" preference for the interpretation of 3D shape remains largely unexplored. Combining behavioral and functional MRI measurements coupled with multivoxel pattern analysis, we show that activations in early visual areas predict best the light source direction irrespective of the perceived shape, but activations in higher occipitotemporal and parietal areas predict better the perceived 3D shape irrespective of the light direction. These findings demonstrate that illumination is processed earlier than the representation of 3D shape in the visual system. In contrast to previous suggestions, we propose that prior knowledge about illumination is processed in a bottom-up manner and influences the interpretation of 3D structure at higher stages of processing.