The Gap Between Aesthetic Science and Aesthetic Experience

For over a century we have attempted to understand human aesthetic experience using scientific methods. A typical experiment could be described as reductive and quasi-psychophysical. We vary some aspect of the stimulus and systematically measure some aspect of the aesthetic response. The limitations of this approach can be categorized as problems on the Y axis (what we measure) and the X axis (what we manipulate). The most enigmatic components of aesthetic experience include inclination to cry, aesthetic rapture, a sense of the sublime, and intense fascination. However, we cannot evoke these 'hot' aesthetic emotions in the lab, at least not with well controlled stimuli on multiple trials. We thus resort to measuring cold, cognitive preference ratings. There are also problems on the X axis. The reductive psychophysical approach explicitly assumes that there are lawful relations between different stimulus dimensions and preferences. It also tacitly assumes that these dimensions are independent and orthogonal. The second assumption is implausible. Whatever stimulus-preference laws we discover are likely to be twisted and modulated when another dimension is added to the stimuli. This 'gestalt nightmare' has long been recognized, but never resolved. This matters, because human aesthetic faculties are probably tuned to the balance and relationship of parts which make up a whole and are indifferent to the parts presented in isolation. I conclude that the future of scientific aesthetics depends on how successfully we can transcend reductive, quasi-psychophysical approaches

Visual cortex activation predicts visual preference: Evidence from Britain and Egypt

The term 'Perceptual goodness' refers to the strength, obviousness or salience of a visual configuration. Recent work has found strong agreement between theoretical, neural and behavioural measures of perceptual goodness across a wide range of different symmetrical visual patterns (Makin et al. 2016). We used these pattern types again to explore the relationship between perceptual goodness and aesthetic preference. A group of 50 UK participants rated the patterns on a 0-100 scale. Preference ratings positively correlated with four overlapping measures of perceptual goodness. We then replicated this finding in Egypt, suggesting that our results reflect universal aspects of human preference. The third experiment provided consistent results with a different stimulus set. We conclude that symmetry is an aesthetic primitive that is attractive because of the way it is processed by the visual system

Visual perceptions of portion size normality and intended food consumption: A norm range model

Smaller portion sizes are associated with lower energy intake. We test a norm range model of the portion size effect on intended intake. A wide range of portion sizes were perceived as normal. Portions perceived as normal did not prompt intended compensatory eating. Portions perceived as smaller than normal prompted intended compensation

The extrastriate symmetry response is robust to alcohol intoxication

Visual symmetry activates a network of regions in the extrastriate cortex and generates an event-related potential (ERP) called the sustained posterior negativity (SPN). Previous work has found that the SPN is robust to experimental manipulations of task, spatial attention, and memory load. In the current study, we investigated whether the SPN is also robust to alcohol-induced changes in mental state. A pilot experiment (N = 13) found that alcohol unexpectedly increased SPN amplitude. We followed this unexpected result with two new experiments on separate groups, using an alcohol challenge paradigm. One group completed an Oddball discrimination task (N = 26). Another group completed a Regularity discrimination task (N = 26). In both groups, participants consumed a medium dose of alcohol (0.65 g/kg body weight) and a placebo drink, in separate sessions. Alcohol reduced SPN amplitude in the Oddball task (contrary to the pilot results) but had no effect on SPN amplitude in the Regularity task. In contrast, the N1 wave was consistently dampened by alcohol in all experiments. Exploratory analysis indicated that the inconsistent effect of alcohol on SPN amplitude may be partly explained by individual differences in alcohol use. Alcohol reduced the SPN in light drinkers and increased it in heavier drinkers. Despite remaining questions, the results highlight the automaticity of symmetry processing. Symmetry still produces a large SPN response, even when participants are intoxicated, and even when symmetry is not task relevant

Symmetry perception for patterns defined by colour and luminance

Perception of visual symmetry is fast, efficient and relies on both early, low-level and late, mid- and high-level neural mechanisms. To test for potential influences of early, low-level mechanisms on symmetry perception, we used isoluminant, achromatic and combined (colour + luminance) patterns in a psychophysical and an event-related potential (ERP) experiment. In the psychophysical experiment, pattern contrast was fixed at individual symmetry discrimination threshold. Participants then judged whether a pattern was symmetric or random. Stimuli at isoluminance were associated with a large bias towards symmetry, achromatic stimuli introduced the opposite bias, while stimuli containing a balance of both colour and luminance were perceived without bias. These findings are in line with distinct contrast sensitivity functions for colour and luminance, with colour providing low frequency information useful for symmetry detection and luminance providing high frequency information useful for detection of detail. The subsequent ERP experiment was run at high contrasts to assess processing of symmetry in suprathreshold conditions. Sustained Posterior Negativity, a symmetry-sensitive ERP component, was observed in all conditions and showed the expected dependence on symmetry. However, interactions between symmetry and contrast type were not observed. In conclusion, while our findings at threshold support models that propose an important contribution of low-level mechanisms to symmetry perception, at suprathreshold, these low-level contributions do not persist. Therefore, under everyday viewing conditions, symmetry perception engages a relatively broad cortical network that is not constrained by low-level inputs

Covert Tracking: A Combined ERP and Fixational Eye Movement Study

Attention can be directed to particular spatial locations, or to objects that appear at anticipated points in time. While most work has focused on spatial or temporal attention in isolation, we investigated covert tracking of smoothly moving objects, which requires continuous coordination of both. We tested two propositions about the neural and cognitive basis of this operation: first that covert tracking is a right hemisphere function, and second that pre-motor components of the oculomotor system are responsible for driving covert spatial attention during tracking. We simultaneously recorded event related potentials (ERPs) and eye position while participants covertly tracked dots that moved leftward or rightward at 12 or 20°/s. ERPs were sensitive to the direction of target motion. Topographic development in the leftward motion was a mirror image of the rightward motion, suggesting that both hemispheres contribute equally to covert tracking. Small shifts in eye position were also lateralized according to the direction of target motion, implying covert activation of the oculomotor system. The data addresses two outstanding questions about the nature of visuospatial tracking. First, covert tracking is reliant upon a symmetrical frontoparietal attentional system, rather than being right lateralized. Second, this same system controls both pursuit eye movements and covert tracking

Electrophysiological priming effects confirm that the extrastriate symmetry network is not gated by luminance polarity

It is known that the extrastriate cortex is activated by visual symmetry. This activation generates an ERP component called the Sustained Posterior Negativity (SPN). SPN amplitude increases (i.e., becomes more negative) with repeated presentations. We exploited this SPN priming effect to test whether the extrastriate symmetry response is gated by element luminance polarity. On each trial, participants observed three stimuli (patterns of dots) in rapid succession (500 ms. with 200 ms. gaps). The patterns were either symmetrical or random. The dot elements were either black or white on a grey background. The triplet sequences either showed repeated luminance (black > black > black, or white > white > white) or changing luminance (black > white > black, or white > black > white). As predicted, SPN priming was comparable in repeated and changing luminance conditions. Therefore, symmetry with black elements is not processed independently from symmetry with white elements. Source waveform analysis confirmed that this priming happened within the extrastriate symmetry network. We conclude that the network pools information across luminance polarity channels

Comparing angular and curved shapes in terms of implicit associations and approach/avoidance responses.

Most people prefer smoothly curved shapes over more angular shapes. We investigated the origin of this effect using abstract shapes and implicit measures of semantic association and preference. In Experiment 1 we used a multidimensional Implicit Association Test (IAT) to verify the strength of the association of curved and angular polygons with danger (safe vs. danger words), valence (positive vs. negative words) and gender (female vs. male names). Results showed that curved polygons were associated with safe and positive concepts and with female names, whereas angular polygons were associated with danger and negative concepts and with male names. Experiment 2 used a different implicit measure, which avoided any need to categorise the stimuli. Using a revised version of the Stimulus Response Compatibility (SRC) task we tested with a stick figure (i.e., the manikin) approach and avoidance reactions to curved and angular polygons. We found that RTs for approaching vs. avoiding angular polygons did not differ, even in the condition where the angles were more pronounced. By contrast participants were faster and more accurate when moving the manikin towards curved shapes. Experiment 2 suggests that preference for curvature cannot derive entirely from an association of angles with threat. We conclude that smoothly curved contours make these abstract shapes more pleasant. Further studies are needed to clarify the nature of such a preference