Keywords

Introduction

Appreciating beauty is part of everyday life, when we contemplate fine arts, architecture, music, and natural scenes. Aesthetic appreciation, like any ordinary phenomenon of human life, triggers affective and cognitive processes that can provide the subject with sensations of hedonic pleasure and cognitive self-reward (Leder et al., 2004). Although humans share several neuropsychological processes, the experience of aesthetic appreciation is undeniably idiosyncratic, and sometimes it is not that simple to find beauty where we were supposed to find it, and more often the same object can elicit different reactions amongst observers. Let us take the following situation as an example.

I once had a conversation with an artist friend (WC) about Salvador Dalí’s Surrealist object, Lobster Telephone (1938). I told her that, though I had a great appreciation for Dalí’s other work, that particular piece irritated me no end: I saw it as a lazy juxtaposition of two randomly selected items. She replied that the role of art was just that – to provoke; to elicit a reaction, any reaction, even an emotionally-negative one, in the viewer. Although I still hold that initial aversive reaction to Dalí’s five versions of the telephone, my friend was right to emphasise the ‘experience’ of the artwork rather than its objective attributes, and consequently the subjectivity implicit in both the intensity and valence of my emotional reaction. Beyond the oft-quoted expression that ‘beauty is in the eye of the beholder’, a Brazilian variant contends that ‘he who loves the ugly holds the perception of beauty’ (quem ama o feio, bonito lhe parece), that is, we are able to distinguish and even empathise with a positive aesthetic experience in another even when we objectively view the object of their desire as ugly. As such, aesthetic experience goes beyond merely a shared and plastic conception of beauty and can elicit conflicting and often contradictory mental and emotional states in the same observer (Fig. 4.1).

Fig. 4.1
An illustration of Salvador Dali's lobster telephone in the year 1936.

Salvador Dalí’s lobster telephone (1938)

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In light of this perceptual variability in response to aesthetic stimuli, there has been increasing interest in neuroaesthetics, a relatively recent field which studies the biological bases underlying aesthetic experiences. Such experiences may include the evaluation of facial attractiveness, the appraisal of paintings, sculptures and other works of art, and complex emotional reactions to beauty, either in the natural environment or to man-made structures. Contributions to the study of neuroaesthetics are wide-ranging, drawing from such dispersed disciplines as visual perception, art theory and emotion, and hold important insights for more established areas of study in attention, face recognition, and cognitive ergonomics.

Beauty can be defined as a property or value of an object, natural scene, or person which engenders a physiological and psychological experience of pleasure and satisfaction. Cognitive neuroscience as a whole is well-placed to provide greater understanding of how humans form and process the experience of beauty, from a predominantly dopaminergic network for encoding hedonic value to the effect of context and long-term memory on the modulation of our individualised experience of beautiful stimuli. Beauty is often predominantly measured in terms of positive affective response to aesthetic stimuli, such as paintings, physically attractive faces and natural scenes, or even the activation of a subset of distinct brain regions, such as the orbitofrontal cortex, a frequent criticism of scientific reductionism levied by colleagues in the humanities (Brown & Dissanayake, 2009).

Within the field of neuroaesthetics, however, the aesthetic experience is not merely reduced to the perception and appreciation of beauty however the global affective and cognitive valuation of external stimuli, either for their artistic or other intrinsic qualities. Pearce et al. (2016) effectively distinguish between the cognitive neuroscience of art and aesthetics, arguing that an appropriate conceptualisation of neuroaesthetics must consider artistic stimuli not merely in aesthetic terms but through a broader context of modulating factors, such as expertise, perceived value, and complex emotional states.

In a series of groundbreaking syntheses, Anjan Chatterjee, Oshin Vartanian, and colleagues (Chatterjee, 2011, 2014; Chatterjee & Vartanian, 2014, 2016; Pearce et al., 2016) have set forth the key aspects within the neuroscience of aesthetics, in what they denominate the triad of aesthetic experience: distinct brain networks for sensory-motor, emotion-valuation, and meaning-knowledge functions in the appraisal of aesthetic stimuli (see Fig. 4.2).

Fig. 4.2
A circular representation of aesthetic experience with Sensory motor, Emotion valuation and Meaning knowledge.

The triad of aesthetic experience (Chatterjee & Vartanian, 2016)

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Defining Neuroaesthetics

Any workable definition of neuroaesthetics must proceed from work in perception, more especially visual perception, given the primacy of this sense in human perception (Kupers et al., 2011). To this end, Ishizu and Zeki (2011) investigated whether similar patterns of brain activity were correlated across different sensory modalities. Their hypothesis, in accordance with Burke’s (2014) assertion of a single representation of beauty across different sensory modalities, was that a similar region of the medial orbitofrontal cortex (OFC) would be activated in response to aesthetic stimuli from both a visual and auditory source. Stimuli classified through ratings as ‘beautiful’, ‘indifferent’, and ‘ugly’ were presented as pairs in an aesthetic judgement task and a control brightness judgement task. The contrast between activation in the aesthetic > brightness task revealed significant activation in the lateral and medial OFC and superior frontal gyrus, indicating a selective OFC response to aesthetic judgement.

A neural system for aesthetic perception has been posited as relying on the same underlying brain structures as those for emotional processing as well as a generalised object-appraisal system (Brown et al., 2011). According to this view, a ‘naturalization’ of neuroaesthetics is required, in which the neural bases of aesthetic perception are more directly linked to the basic valuation of sensory stimuli, specifically mapped to the gustatory cortex, consistent with the identification of the anterior insula as the most concordant area of activation between studies of aesthetic judgement (Brown et al., 2011), an area more commonly associated with the valuation of taste.

Reber et al. (2004) proposed that aesthetic pleasure is related to the fluency with which an observer can process the characteristics of a given object. The easier the integration of the plastic elements, the greater the congruence construction, so the more fluent this observation can be, the greater the chances of positive attribution to what one observes. The fluidity of this perceptual dynamics is associated with the elicitation of pleasure, and negative reactions are common when observing asymmetric or disharmonic combinations (Ikeda et al., 2015). An absence of or interruption to this fluidity may have been one of the main contributions to our sometimes negative affective experiences with aesthetic stimuli, as in the author’s reaction to Dalí’s Lobster Telephone described at the beginning of this chapter.

In a study with functional magnetic resonance imaging (fMRI), to understand the neural mechanisms underlying the aesthetic and emotional aspects of colour perception, Ikeda et al. (2015) verified activation of the left medial orbitofrontal cortex (mOFC) during the observation of visually congruent stimuli and the left amygdala during the observation of incongruent stimuli (Ikeda et al., 2015). Their results led them to conclude that stimulus valuation is conditioned by automatic visual processes of stimuli features mediated by the amygdala, and the aesthetic values measured by the mOFC. These results suggest that differences in appraisal aspects of object valence may be due to separate brain regions.

Additionally, while studying different behavioural and electrophysiological responses to aesthetic experiences with modern art, Pihko et al. (2011), Leder et al. (2014), and Else et al. (2015) suggested that the observers’ backgrounds should be considered when interpreting differences in response, as both the expertise level of the observer and semantic content, such as labels and titles (Gerger & Leder, 2015), can interfere in the implicit evaluation of art. For example, Gerger and Leder (2015) found varying activation in the corrugator muscle of the eyebrow and the zygomatic major facial muscle of viewers according to whether the artwork is titled or untitled, whether semantically congruent or not. These different, often discrete, muscle activations can be recorded by facial electromyography (fEMG), and the data collected by Gerger and Leder (2015) suggests that when the title was absent or incongruent, observers reported less interest and subjective aesthetic appreciation.

Although the results of Gerger and Leder (2015) appear to corroborate the relationship between the valuation of experience and perceptual fluency (Reber et al., 2004), this pattern of response may be more directly associated with the fact that study participants may have been influenced mainly by the automatic emotional processes underlying perceptual fluidity, as previously proposed by Brown et al. (2011). Corrugator and zygomatic contraction is associated with greater cognitive effort and, therefore, it is also assumed to be reflective of a reduction in perceptual fluency and consequent increase in negative experience reports. What the authors point out, however, is that fluidity of processing in the conjunction of characteristics and contextual information alone is not sufficient for positive aesthetic evaluations, as often moderate levels of cognitive effort can contribute to the positivity of aesthetic experiences, a fact observed in cases of expert evaluations that focus on art in a more elaborate way (Gerger & Leder, 2015).

Motivation and Facial Attractiveness

Another fundamental aspect of beauty research concerns its importance for the maintenance of the species. Evolutionarily, attractive faces constitute an important factor both for the establishment of sexual relations (reproductive ends) and for parental behaviour (Hahn & Perrett, 2014), because they usually symbolise fertility, gene quality, and health (Chatterjee & Vartanian, 2016).

Thinking in reproductive aspects, in heterosexuals, there is the activation of a neural network involved in motivation and reward systems, involving structures such as the nucleus accumbens, the medial prefrontal cortex, the anterior dorsal cingulate and the orbitofrontal cortices, which shows a high level of response to attractive rather than unattractive faces of people of the opposite sex. Amongst both heterosexuals and homosexuals, Hahn and Perrett (2014) point out that there are comparative studies in the literature that indicate greater activation of the orbitofrontal cortex and dorsomedial thalamus when observers are presented with faces of people of the desired sex, regardless of sexual orientation or even the gender of the observer. These results are consistent with previous research by Ishai (2007), who found greater OFC activation in response to attractive male faces in heterosexual women and homosexual men and greater OFC activation in response to attractive female faces in heterosexual men and homosexual women.

Similar to mate bonding behaviours amongst adults, the attractiveness of an individual infant’s face appears to influence both caregiver behaviour and the quality of care (Langlois et al., 1995). Cute or attractive children are more likely to receive care and positive affects, such as tenderness, and less likely to suffer aggression (Hahn & Perrett, 2014), which is possibly related to the fact that cute children are usually seen as healthy and worthy of parental investment. In an fMRI study, Glocker et al. (2009b) found that the baby schema, i.e., ‘a set of infantile physical features’ (Glocker et al., 2009a), activates the nucleus accumbens (NAcc), a key structure of the reward system, in nulliparous women.

Sexual and gender differences in neural responses modulated by attractive faces and infant cuteness must be better investigated, but what we know so far leads us to the hypothesis that baby facial attractiveness has its influence in human caregiving, regardless of kinship, and attractiveness in adult faces continues to play a key role in mating bonds.

Beauty and the Beast? Aesthetics and Complex Emotions

The evaluation of aesthetic stimuli is not only related to aspects of positive or negative valuation or reward processing. It is often related to the development of complex emotions such as awe, envy, and anxiety (Armstrong & Detweiler-Bedell, 2008), closely linked to the perception of the sublime in art, a philosophical concept underpinning our understanding of subjective emotional responses to aesthetic stimuli (Chatterjee & Vartanian, 2016). In a fMRI study, Cupchik et al. (2009) found significant bilateral activation in the insula when participants viewed artworks, consistent with an emotional aspect in aesthetic evaluation, suggesting that the aesthetic experience emerges from a top-down guiding of attention and bottom-up perceptual cues for fluency and visual organisation.

One key network in the subjective evaluation of aesthetic stimuli is the default-mode network (DMN), implicated in mind-wandering, autobiographical memory, and other processes. Vessel and colleagues tested fMRI response in participants rating artworks on how ‘moving’ they perceived them to be, on a scale of 1–4 (Vessel et al., 2012). They found an increase in activation in several areas within the DMN, including the anterior medial PFC, lateral orbitofrontal cortex, posterior cingulate cortex, and hippocampus, in response to more emotionally ‘moving’ artworks but, importantly, only the most highly rated images for emotional resonance led to an activation in the aMPFC, in contrast to other studies (Kawabata & Zeki, 2004; Ishizu & Zeki, 2011) which found activation varied linearly in response to the emotional response to aesthetic stimuli. This pattern of results suggests that a ‘sublime’ experience to aesthetic stimuli depends on an intense emotional reaction and corresponding activation in the anterior medial PFC in conjunction with the more commonplace aesthetic valuation occurring primarily in the OFC.

Judging Books By Their Covers

Despite its prevalence and the automaticity with which it occurs, the so-called ‘halo effect’ is a frequently employed cognitive bias that guides and directs our decision-making and judgement, causing relevant aspects to be relegated and others, such as aesthetics, to stand out and interfere with one’s general judgement, even when there is sufficient information available to form an independent evaluation of extraneous salient attributes (Nisbett & Wilson, 1977).

Individuals whose faces are more attractive are often judged more positively in various dimensions and also receive different treatment in different domains of social life (Liang et al., 2010). The evaluation and personality traits attributed to facial attractiveness seem to have emerged as an adaptive response, in the light of evolutionary hypotheses that misshapen faces were associated with parasites, disease, and a lack of biogenic immunity. This evolutionarily driven preference for attractive, unblemished faces affects even otherwise healthy individuals, who nevertheless have a facial asymmetry conveying inferior levels of health, intelligence, and sociability (Zebrowitz et al., 2002; Liang et al., 2010).

Conclusion

The perceptual, behavioural, and neural mechanisms involved in the perception of aesthetic stimuli are key to our understanding of the everyday interactions and motivations which characterise our relationships with the natural and man-made world. The aim of understanding the cognitive processes underlying aesthetic appreciation has been a key driver for applying the tools and methods of cognitive neuroscience to the field of art and aesthetic stimuli and establishing links with the parallel study of perceptual, emotional, attentional, semantic, memory, and decision-making processes. Investigating neural networks engaged in decoding and valuing aesthetic content is an important challenge that should involve other areas of knowledge. For the phenomena of aesthetic appreciation to be understood in all their complexity, it is necessary to integrate into the physiological aspects also the historical, social, and cultural aspects, which holistically make up the person.