Tài liệu CHAPTER TwENTY ONE A BIOLOGICAL APPROACH TO A MODEL OF AESTHETIC ExPERIENCE OSHIN VARTANIAN AND MARcos NADAL pdf

A BIOLOGICAL APPROACH TO A MODELOF AESTHETIC ExPERIENCE Recently, Leder and colleagues 2004 introduced an information-processing model to account for aesthetic experience.. Recently, Led

A BIOLOGICAL APPROACH TO A MODEL

OF AESTHETIC ExPERIENCE

Recently, Leder and colleagues (2004) introduced an information-processing model to account for aesthetic experience This model breaks the computation

of the aesthetic response into five stages, associating each stage with a particular

process of interest In this paper we review results from recent neuroimaging

studies of visual aesthetics to determine the extentto which they support this model.Inaddition, we derive specific hypotheses from the model that remain to

be tested at a biological level We argue that because all the cognitive and emotional processes that comprise the model are instantiated in the brain, one should in principle be able to test this model using biological methods We conclude that the model is a promising framework within which to conduct such work on aesthetics

There is now general agreement that the aesthetic experience is the outcome

of a complex interplay of cognitive and affective processes Recently, Leder and colleagues introduced an information-processing model to account for the

interaction of various component processes in the computation of aesthetic

experience (Lederel al., 2004, 2005) Their model of aesthetic experience was

described at the psychological level, and unlike other models (e.g., Chatterjee, 2003) was not designed to account for the biological underpinnings of aesthetic experience per se Nevertheless, the model of aesthetic experience has certain characteristics that make it amenable to neuroscientific investigation First, it breaks the computation of the aesthetic response into various stages, associating each stage with a particular process of interest Because neuroscientists have studied those processes in contexts other than aesthetics, rudimentary cortical maps of their neural correlates havebegunto emerge This feature allows one to test hypotheses about whether any particular process of interest iSOlated within this model will map onto plausible cortical structures Second, and critically, there are built-in temporal constraints in the structure of the model In other words, information flows in specified ways through the system, and this orderly

flow has certain temporal characteristics associated with it This feature allows

one to test the temporal dynamics of information flow using time-course and

functional connectivity analyses

The aim of this chapter is a~ follow.s First, we will review some of the key

features of themo~el of aesthetIc expenence that are particularly relevant to our

arguments We wIll not present a detailed account of the model as these exist

elsewhere ,(Lederel al., 2004, 2005) Second, we will compare this model to

Chatterjee s (2003) model of visual aesthetics, developed specifically to address

on the biOlogIcal bases of the aesthetic experience that speak to some of the

predlcllons and hypotheses derived from the model of aesthetic experience

Essenllally, we beheve that biOlogical approaches have the potential to inform

us about the vahdlty of thIS model, and that predictions derived from the model

can10tum be tested at a biological level Although in this paper we will focus

on neuroimaging studies only, the arguments are also relevant to

neuropsychological approaches involving patient populations (e.g., Chatterjee,

2004) Fmally, we wIll assess the current status of the model of aesthetic

experience based on the available biological data, and will outline specific

hypotheses that can be used to test the so-called joints in the system

A Model of Aesthetic Experience

Here we pre~ent a stripped down version of Leder el al 's (2004, 2005)

model of aesthettc expenence The model of aesthetic experience is comprised

of five mformatlOn-processmg stages that are connected in sequence, as well as

through several feedback loops (see Fig 21-1) Information flow is

unldrrectiOnallo some parts of the model and bidirectional in others such that

certain phases involve bottom-up as well as top-<lown processing.fu addition,

there IS an affecllve evaluation stream (Continuous Affective Evaluation) that

nms p",:"lIel to thIS sequenllal stream and receives its output The input into the

system IS the artwork Itself, which for the purpose of this paper will be limited

to vls~~l1 s~lmuh, speCifically paintings Then, at each stage, a particular

operation .IS perf~nned on the artwork, therefore extracting various

characlensllcs from It The ftrst stage involves perceptual analyses At this stage

features such as compleXJty or symmetry are distilled For example, there is

mU~h research demonstrating that people prefer more 10 less symmetrical

deSIgn Accordmg to the model of aesthetic experience, this information is

processed rather early in the stream This stage is not under the influence of

top-down processes and IS sllmulus driven The second stage involves implicit

memory IUtegratton, where the perceptual information is related to past

expenence For example, we know that people prefer colors that are more

deemed prototypical depends in part on personal expenence Essenllally, at thIS stage people compare what they see to what they know, and this affects their responses to it This stage is presumed to be under the indirect influence oftop-down processes The third stage mvolves exphClt clasSIficatiOn, and this IS where expertise comes into play At this point, the person analyzes content information, and also explicit information about the style of the artwork There

is much evidence demonstrating that expertise affects the way in which artworks are processed (Hekkert& van Wieringen, 1990), and this is one of the stages where the difference between experts and novices would be apparent

Insome ways the fmal two stages of the model are the most interesting not only because they tap higher-level cognition, but also because they probably

exert the most influence on aesthetic experience The penultunate stage 15

referred to as cognitive mastering, the moment at which interpretation or

meaning is imposed on the artwork Thus, having already distilled its perceptual properties and placed it within self-referential (implicit memory integrallon) and explicit (explicit classification) contexts, we make sense of what It IS that we see Of course, what one observesisalso influenced by experllse 10the VIsual arts so that different cues become more or less important in giving meaning to the'artwork (parsons, 1987) In the final stage referred to as evaluation we appraise the meaning or interpretation that was placed on the artwork durmg mastering This evaluative stage generates two outputs: aesthetIc judgment and aesthetic emotion, which are the endpoints of the aesthellc expenence If cognitive mastering is successful and the subject has successfully mterpreted the artwork it will be evaluated as either a good or a poor work of art Those aestheti~judgments will be accompanied by po~itive and negative aesthetic emotions respectively On the other hand, If cogmtlve mastenng IS unsuccessful, the artwork will likely be evaluated as a poor work of art, accompanIed by

Insummary, the model of aesthetic experience hasfiv~ cognitive stages that are interwoven by an affective component, although the lOfluence of affect on the computational process varies along the stream The model of aesthetIc experience presents a hypothetical route for the generatIon of the two most common dependent variables in aesthetic research: AesthetIC judgment and aesthetic emotion Aesthetic emotion can be seen as the fmal affectIve byproduct of successfuJ mastering, whereas aesthetic judgment can tap eIther the cognitive outcome of the mastering stage (i.e., quahty), or Its affecllve

consequences.

Theoretical Links to Other Models

Chattetjee's (2003) model of visual aesthetics represents a recent

neuroscientific framework for investigating aesthetic experience Chatterjee

(2003) has suggested that aesthetic experiences related to visual ohjects involve

three visual processing stages common to the perception of any visual stimulus,

as well as an emotional response, a decision, and the modulating effect of

attention.Inthe frrst stage early visual processes hreak the stimulus down into

simple components, such as color, shape, and so on, which are extracted and

analyzed in different brain areas The second stage, intennediate vision, includes

a series of operations that segregate some elements and group others, forming

coherent representations In late visual stages, included under the

representational domain in this model, certain regions of the ohject are selected

for further scrutiny At this moment, memories are activated, and ohjects are

recognized and associated with meanings This visual analysis leads to emotions

associated with the aesthetic experience, and it grounds decisions about the

stimulus However, this is not a strictly linear model In fact, it posits an

important feedback flow of information via attentional processes, from higher

visual and emotional levels towards early visual processing

A comparison of the models proposed hy Leder and colleagues (2004) and

Chattetjee (2003) reveals similarities and differences Both models acknowledge

the importance of early and late visual processes in the generation of an

emotional response and the elaboration of a decision They also take into

consideration the influence of complexity, order, grouping, and many other

variables familiar to experimental aestheticians, as well as the interaction

between affective and cognitive processes such as the activation of memories

and the search for meaning Additionally, hoth models suggest two different

outputs: an emotional response or aesthetic emotion versus a decision or

aesthetic judgment However, at a more specific level, these models have

emphasized different aspects of aesthetic experience Chattetjee's (2003) model

deals extensively with perceptual processes, hut makes little mention of higher

cognitive processes, such as interpretation or classification In contrast, Leder

and colleagues (2004) suhsumed all perceptual processes in a single stage and

did not explicitly consider a function for attention, instead specifying higher

cognitive processes in detail, and awarding them a central role in the aesthetic

experience Fig 21-1 shows a comhined representation of both models,

illustrating their similarities and differences

There could be several reasons behind the differences between Chattetjee's

and Leder and colleagues' models First, Chattetjee's (2003) ohjective was to

create a framework for neuroaesthetics that was fumly based on frodings from

visual neuroscience.Inhismode~theprocessesinvolved in visual ohject recognition

Elllliualioll

-,

constitute the starting point for visual aesthetics, so it is not surprising that they

figure so prominently in his modeL This is also the reason why attention is

awarded a central role: It is known to exert top down modulation of early

visual processing On the other hand, Leder and colleagues (2004) aimed to

present an information-processing model of the stages involved in the aesthetic

processing of visual artistic stimuli In this sense, the starting point of the model

was their analysis of modern art (Lederef al., 2004, p 491) They believe that

understanding plays a critical role in the aesthetic experience of modern art, in

the sense that comprehending an artwork alters the way in which it is

experienced,

However, there is also a deeper difference between the two models, and it

refers to the way in which they conceive of the aesthetic experience itself,

Chatterjee (2003) believes the notion of disinterested interest adequately

captures the aesthetic experience such that "the viewer experiences pleasure

without obvious utilitarian consequences of this pleasure" (Chatterjee, 2003,

p.55) From this perspective 'judgments about an aesthetic object might be

considered outside the core aesthetic experience" (Chatterjee, 2003, p 56) In

fact, the model seems to include a decision phase only as an approach to

laboratory settings, where participants are usually asked to state their

preferences or make decisions about a certain aspect of the stimulus

Conversely, Leder and colleagues (2004) believe aesthetic experiences arise

when "exposure to art provides the perceiver with a challenging situation to

classify, understand and cognitively master the artwork successfully" (Lederet

aI.,2004, p 493) This successful mastering of the artwork involves, cspecially

in relation to modern art, style-related processing, which results from the

acquisition of expertise, In this model, the judgment of the aesthetic object is an

important element; in fact, together with aesthetic emotion, it is the main output'

of the model In sum, whereas Chatterjee's (2003) proposal can be considered as

a neuroscientific model of aesthetic preference for a broad range of visual

objects, Leder and colleagues' (2004) proposal is an information-processing

model of aesthetic judgment of visual works of art Here we chose to focus on

the model of aesthetic experience because we were particularly interested in the

higher-level cognitive and emotional processes that mediate aesthetic

experience, and those are treated more thoroughly in the model of aesthetic

experience,

Neurophysiology and the Aesthetic Experience

Why is the model of aesthetic experience useful for biological approaches to

the study of aesthetics? There are three reasons First, the model incorporates

cognition and emotion-broadly defined-in the computation of the aesthetic

dissociating the neural pathways belonging to those modes of information processing What we know from neuroscience can be used to test predictions from the model Second, at a more micro level, many of the component processes that characterize each of the five stages, namely perceptual (visual) analyses, implicit memory integration, explicit classification, cognitive mastering, and evaluation have been studied extensively by neuroscientists as well, and at least at a rather gross level we know a little about their neural correlates This makes it possible to test more specific hypotheses about the differential engagement of each of these processes in the computation of the aesthetic response, Finally, the structure of the model of aesthetic experience places temporal constraints on the process For example, by definition, one cannot engage in cognitive mastering unless one has carried out a perceptual analysis first This can be a valuable tool in neuroimaging because one can conduct time-course and functional connectivity analyses to see whether the time courses of activation corresponding to various structures occur in accordance with the predictions of the modeL

Next we will review some neuroscientific evidence that can be used to assess the validity of the model Although we will discuss studies in visual aesthetics specificaIly, we emphasize that biological data collected in studies of vision, memory, attention, and emotion can shed light on this process as ~ell. FoIlowing this review, we will highlight specific hypotheses that can be denved from this model and tested empirically to validate the model at a blOlog!cal level

Components of the Aesthetic Experience

To date, five neuroimaging studies have appeared that have anc~pted to shed light on the cortical underpinnings of the aesthetic response Four IOvolved the technique of functional magnetic resonance imaging (tMRI), and one involved magnetoencephalography (MEG) Although none of the studIes was conducted with the specific aim of testing any predIctIon denved from the model of aesthetic experience, their results nevertheless inform us about the accuracy of the model We wiIl next review the key findings of each study, and their bearing on the model of aesthetic experience

Aesthetic Judgment Jacobsen ef al (2006) asked a fundamental question: What are the specific neural correlates that distinguish aesthetic judgment from other types of judgment? The "other" judgment in their study involved judgment of symmetry

Recall from the description of the model of aesthetic experience that judgment

of symmetry occurs at the first stage involving perceptual analysis, whereas

aesthetic judgment follows the fifth stage of the process-evaluation Because

subjects were presented with the same kind of stimuli in the symmetry and

aesthetic judgment conditions but asked to make different types of judgments,

Jacobsen el at. (2006) argued that the contrast between aesthetic and symmetry

trials would reveal the brain areas that are involved in aesthetic judgment, in

relation to symmetry judgment This contrast revealed activation in several

frontal, parietal, and temporal structures including the frontomedian cortex, the

precuneus, the temporal pole, and thet~rnporoparietal junction According to the

model of aesthetic experience, the activation pattern that reflects aesthetic

judgment must differ from the pattern that reflects symmetry judgment, and

Jacobsenel aI's (2006) results confirm this hypothesis Recall that the activation

pattern that was revealed in the contrast of aesthetic versus symmetry judgment

reflects multiple cognitive and affective processes that operate on the artwork

following the perceptual analysis at the first stage, until an aesthetic judgment is

eventually fonned These processes include implicit memory integration,

explicit classification, cognitive mastering, and evaluation From the vantage

point of the model of aesthetic experience what is interesting about Jacobsen et

al.s (2006) resulls is that several of the activated structures have been linked to

the aforementioned component processes Nevertheless, additional studies in

which the design allows the comparison of successive stages of information

processing are necessary for determining the contribution of each cortical

structure10a specific component process

Affect, Cognition, and Aesthetic Experience

No study to date has investigated differences in the neural correlates of

aesthetic judgment versus aesthetic emotion directly At a rudimentary level,

this would involve presenting subjects with the same stimuli under two different

conditions: In onc condition they would be asked to rate the stimuli onquality,

thus tapping the cognitive component of aesthetic judgment exclusively (Leder

el al., 2005; Vartanian & Goel, 2004a) In the other condition, they would be

asked to rate the same stimuli onpleasure, thus tapping the affective component

of aesthetic emotion exclusively (Lederel al., 2005; Vartanian & Goel, 2004a)

However, three fMRl studies to date have tackled facets of aesthetic affect or

emotion, and can thus shed light on whether variations in aesthetic emotion

correspond to variationsincortical and subcortical activation

Vartanian and Goel (2oo4b) sought to determine whether aesthetic

preference toward works of art is characterized by a "disinterested" or cognitive

stance as presumed by some, or whether is it underwritten by an emotional

response toward properties of artworks They hypothesized that if aesthetic preference were mediated by emotion, then it should involve brain structures that have been implicated in processing emotion On the other hand, if aesthetic preference were primarily a cognitive process, then it should involve brain structures that have been implicated in evaluation under emotionally neutral conditions In the scanner, subjects viewed and rated paintings on aesthetic preference Preference was defined as the degree of liking for a pain ling The results demonstrated that activation in several cortical structures that have been implicated in processing emotion or reward covaried as a function of preference ratings, including the visual cortex, the caudate nucleus, and the cingulate sulcus

What do the results of Vartanian and Goel (2004b) tell us about the model of aesthetic experience? Recall that the affective evaluation stream runs parallel to the information-processing stream, and it receives continuous input from it This means that a subject interacting with a work of art can provide a preference rating for that artwork at any given point along the information-processing sequence, and need not have processed the artwork up to a particular stage in the sequence before a rating can be generated Therefore, one possibility is that the results of Vartanian and Goel (2oo4b) shed light on the cortical and subcortical structures that mediate Continuous Affcctive Evaluation, and indicate the areas thal one should expect to see activated whenever subjects are asked to indicate their liking for given artworks Another possibility is that the ratings offered by the subjects in this study reflect aesthetic emotion, which can only occur following the evaluation stage An additional sludy in which ratings are collected at specific time points can address this issue

Kawabata and Zeki (2004) presented their subjects with paintings that they had rated as beautiful or ugly prior to viewing, and rated them again in the scanner It is important to note that although beauty has affective and cognitive components, it draws more heavily from the latter than from the fonner component (Leder el al., 2005) In contrast, preference also has affective and

cognitive components, but it draws more heavily from the fonner thanfr~~ t~e latter component (Lederel al., 2005) Their results demonstrated that acllvtly m

the orbital frontal cortex was greater for stimuli classified as beautiful, and the authors argued that this activation in the orbital frontal cortex was due to the reward value of beautiful paintings

In the third fMRl study on this topic, Skov el al., (2005) presented their

subjects not with paintings, but with stimuli from the Inte~ation.al Affective Picture System The lntemational Affective Picture System IS an lDventory of pictures that have been categorized as emotionally positive,~egative, or neutral Subjects were asked to view and rate each stimulus as beautiful,u~ly, or neu~al

in the scanner Compared to ugly pictures, beautiful pictures activated a Wide

network of areas including the occipital, parietal, and frontal lobes However,

when subjects rated pictures as beautiful despite the fact that they were

emotionally negative (e.g., finding a scene that exhibits death or injury

beautiful), there was activation in a somewhat different network than before,

again including the occipital, temporal, and the frontal lobes, but in particular

bilateral orbital frontal corlex

What do the results of Kawabata and Zeki (2004) and Skovef al.(2005) tell

us about the model of aesthetic experience? Despite methodological differences,

these studies share a critical feature: Both studies attempted to isoJate those

cortical structures that were activated relatively more by stimuli evaluated as

beautiful According to the model of aesthetic experience, evaluations of beauty

tap aesthetic judgment Thus, its computation can only occur following

processing along all five stages of the model, culminated by evaluation In other

words, activation in the orbital frontal cortex is likely not in relation to

Continuous Affective Evaluation Rather, it is more likely that certain affective

properlies of beauty are computed in the orbital frontal corlex Activation in the

orbital frontal corlex has inturnbeen linked to a wide array of processes, but in

particular to complex reward, hedonic, and emotion interactions (Kringelbach,

2005; Kringelbach&Rolls, 2004)

Using magnetoencephalography (MEG), Cela-Conde ef al. (2004) recorded

brain activity while subjects judged the beauty of a series of stimuli The

greatest difference between MEG andfMRIhas to do with temporal and spatial

resolution Whereas MEG has a low spatial resolution compared withfMRI, its

temporal resolution is significantly greater In addition to locating brain activity

in space, this technique affords information about its temporal course In

Cela-Conde and colleagues' (2004) study, brain activity during the first second after

stimulus onset was broken down into two phases, early latencies (100 400 ms)

and late latencies (400-1000 ms) The results demonstrated that during late

latencies activii)' in the left dorsolateral prefrontal corlex (DLPFC) was

significantly greater when participants judged stimuli as beautiful as compared

to the non-beautiful condition

Previous studies can help us clarify the relation between these results and the

model of aesthetic experience The literature suggests that the dorsolateral

prefrontal corlex is involved in the process of decision-making based on

perceptual (Heekereo ef al., 2004) and/or affective (Davidson & Irwin, 1999;

Herringtonef al., 2005) information Krawczyk (2002) provided an integrative

view of the role of this area: "The left DLPFC may playa privileged role in

decision making that is better constrained, has fewer options, and which may

have preexisting reward characteristics that make for a more confmed set of

rules for deciding" (Krawczyk, 2002, p.66I) Thus, dorsolateral prefrontal

cortex activity seems to be related to conscious deliberation about different

certain limbic areas (Wallis and Miller, 2003)

The fact that activity in early latencies was unrelated with beauty ratings, coupled with results from previous studies, suggest that Cela-Conde and colleagues' (2004) results reflect the neural correlates of the last two cognitive stages posited in the model of aesthetic experience Itis during these stages that the success of cognitive mastering in producing satIsfactory understanding IS

monitored Also, it is suggested that the subjective experience of success or

failure in understanding can initialize top-down information processing In fact,

monitoring other cognitive processes, as well as initiating top-down processes,

has often been associated with dorsolateral prefrontal corlex activity The task that Cela-Conde and colleagues' (2004) participants were asked to perform was

a quick judgment of the image Images were presented for only 3 seconds, and most of the participants' response times were below 2s Therefore, we beheve that it is plausible that as Leder and colleagues (2004, p 503) anticipated, their judgments may have relied heavily on affect-based heuristics These considerations reinforce the idea that the left dorsolateral prefrontal corlex might be involved in a number of processes, including the evaluation phase, the initiation of the feedback loops posited by the model of aesthetIc expenence, and the interaction between cognitive and affective states

Summary

Vartanian and Goel (2004b), Kawabata and Zeki (2004), Skovef at (2005)

and Cela-Conde ef al. (2004) were interested in determining the neural correlates of preference and beauty, two variables that have affective and cognitive components The areas activated by Vartanian and Goel (2004b) may have highlighted those cOrlical structures that mediate Contmuous Affecllve

Evaluation, or those associated with aesthetic emotion As expected, they

include the visual corlex, the caudate nucleus, and the cingulate sulcus These areas have been shown to be activated by emotions, and in particular by sahent stimuli about which one can form an affective impression rather automatically, such as faces or pictures from the International Affective Picture System In contrast, the studies by Kawabata and Zeki (2004) and Skov ef al (2005)

attempted to isolate those cortical structures that are actIvated more when a stimulus is evaluated as beautiful Presumably, both studies tap aspects of aesthetic judgments According to the model of aesthetic experience? beauty bas affective and cognitive components and it results from an evaluallon that can only occur following processing along all five stages of the model The results indicate that evaluating a stimulus as beautiful was asSOCIated WIth mcreased activation in the orbital frontal cortex Activation in the orbital frontal cortex has

inturn been linked to a wide array of processes, but in particular tn complex

hedonic and reward-emotion interactions (Kringelbach, 2005; Kringelbach &

Rolls, 2004) Finally, Cela-Conde et aI's (2004) results seem to reflect cognitive

processes included in later stages of the model of aesthetic experience, including

cognllIve mastering and evaluation Activity in the dorsolateral prefrontal cortex

has often been associated with monitoring and initiating top <lown infonnation

flow, as well as with decision-making However, we suggest that in this

particular instance these cognitive processes were also influenced by affective

information received from orbital frontal cortex or subcortical structures

Testing the model of aesthetic experience at a biological level

Itgoes without saying that the validity of the model of aesthetic experience

as an accurate explanatory framework for aesthetic experience must be

detennioed at the behavioral level flfSt However, we believe that because0/1

the processes that comprise this model, including perceptual analysis, implicit

memory integration, explicit classification, cognitive mastering, and evaluation

are instantiated in the brain, one can also ascertain the extent to which

hypotheses derived from the model can be validated at a biological level We

have already discussed the extent to which results from a number of tMRl and

MEG studies fit general predictions from the model of aesthetic experience

However, none ·of those studies was designed to test predictions derived from

the model of aesthetic experience We believe that five issues in particular can

betested effectively at a biological level, and that those results Can be used to

assess the validity of the model

First, Leder el01. (2004) argued that the context in which an object is viewed

affects the way in which it is processed For the predictions of the model of

aesthetic experience to hold, the input into the system must be designated as an

artwork Essentially, this is based on the argument that the cognitive and

emotional processes that are brought to bear when processing an object as an

artwork will differ from the processes that will be involved when the same

object is not processed as an artwork Itis possible to test this hypothesis at a

biological level, and to determine whether performing identical tasks on a set of

stimuli will activate different cortical structures depending on whether they are

deSIgnated as artworks or not This could help determine whether a critical

assumption of the model holds true at a biological level

Second, the model of aesthetic experience does not include top-down

influences on perceptual analyses However, several studies, such as Kaestner

and Ungerleider's (2000) or Poghosyan and colleagues' (2005) have shown that

attentton modulates the processing of relevant visual stimuli by enhancing

neuronal responses at different levels of visual processing in the brain Attention

seems to modulate neural responses to certain locations of the visual field, whole visual objects or specific visual features, such as color or shape.

Although it has been noted that these modulatory effects are stronger in

extrastriate visual areas, it seems that different features of selective attention can

also affect activity in striate cortex Furthennore, it has also been shown that the emotional valence of images can modulate activity in visual areas (Lang el01.,

1998; Schulman el01.,1997) Hence, if future neuroimaging studies of aesthetic appreciation include strategies to control affective and attentional processes, they might be able to detennine whether these processes exert top <lown influences on early perceptual analyses

Third it is well established that expertise plays an important role in the way artworks' are processed Numerous studies have demonstrated systematic differences in the ways experts and novices view artworks (Bekkert & van Wieringen, 1990; Nodine el 01., 1993) This hypothesis can be tested at a biological level According to the model of aesthettcexpenen.ce, differences due

to expertise become evident in the third stage (ex!'"clt classificatton) when the person analyzes content information and expliCit mformatton about the style of the artwork This process should draw on categonzatlon and memory, and different activation patterns should characterize those processes in experts and

novices.

Fourth, a critical topic in the early days of aesthetic research involved the aesthetic threshold, although interest in this topic has subSIded over the years (Jacobsen, 2006) Rather than calculating the aesthetic threshold, researchers are using presentation thresholds that are appropriate for thelT particular Issues of interest (e.g., Leder el01., 2006) By reliance on a combination of be?avioural and neuroimaging techniques (especially MEG), the temporal dynanucs of the aesthetic experience, as well as the engagement anddisengage~ent of different stages (processes), can be investigated For ex~mple, what IS the mmlJ~al amount of time necessary for explICIt classIlkatton, and does explIcit

classification in fact require more time than implicit memory ~t.egratlO~, as ~e

model suggests? Are implicit memory integration and expllclt clas~Ilicatlon associated with different' patterns of cortical actIvation and lInked to

characteristic time courses?

Fifth what is the relationship between the two major outputs of the system, namely ;"'sthetic judgment and aesth~tic emotion? This is a p~oblem that has haunted philosophers and psychologISts at least smce the 18 cenDlfy ThIs requires a design in which subjects are instructed to process art stlfOuII that can

be evaluated successfully under two different conditIOns: In one condlttonth~y will rate them on quality, broadly speaking, and in the other conditton they WIll rate them on a measure of liking, broadly speaking If the model of aesthetIc

experience is correct, the neural correlates of these two outputs must be

different

Conclusion

aestheltc expenence along narrow levels of analysis In contrast the model of

aesthetic expe~ence provides a general framework for aesthetic' experience at

the psychologIcal le~el, and yet can be tested experimentally using biological

methods at a more ffi!cro level (see also Martindale, 2001) We believe that the

model ofaestheti~expcrience is a promising model for biological investigations

of aesthetic expenence.

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