Processing fluency theory of aesthetic pleasure
The processing fluency theory of aesthetic pleasure is a theory in psychological aesthetics on how people experience beauty. Processing fluency is the ease with which information is processed in the human mind. The theory is based on four basic assumptions:
- Objects differ in the fluency with which they can be processed. Variables that facilitate fluent processing include objective features of stimuli, like goodness of form, symmetry, figure-ground contrast, as well as experience with a stimulus, for example repeated exposure or prototypicality.
- Processing fluency is itself hedonically marked (that is, it possesses an inherent affective quality) and high fluency is subjectively experienced as positive.
- In line with the "feelings-as-information" account, processing fluency feeds into judgments of aesthetic appreciation because people draw on their subjective experience in making evaluative judgments, unless the informational value of the experience is called into question.
- The impact of fluency is moderated by expectations and attribution. On one hand, fluency has a particularly strong impact on affective experience if its source is unknown and fluent processing comes as a surprise. On the other hand, the fluency-based affective experience is discounted as a source of relevant information when the perceiver attributes the experience to an irrelevant source. This helps explain the inverted U-shaped function often found in research on the effect of complexity on preferences: very complex patterns are not judged as beautiful because they are disfluent, and patterns are judged as more beautiful when they become less complex. When viewers perceive a simple pattern, they are often able to detect the source of fluency—the pattern's simplicity—and do not use this experience of ease for judging the beauty of the pattern.
The processing fluency theory of aesthetic pleasure emphasizes the interaction between the viewer and an object in that it integrates theories and a wide range of empirical evidence that focus on effects of objective stimulus attributes on perceived beauty with those that emphasize the role of experience, for example by invoking prototypicality. In this theory, beauty is seen as an experience that has nothing to do with artistic merit: Beautiful works of art may be without any merit whereas good art is not necessarily beautiful.
The theory resolves the apparent paradox of inborn and acquired preferences. For instance, infants prefer consonant melodies. According to the fluency account, this is because infants share perceptual equipment that make them process consonance in music more easily than dissonance. When children grow up, they are exposed to the music of their culture, resulting in culture-specific musical fluency. This familiarization explains why individuals from different cultures have different musical tastes. In addition, the theory helps explain why beauty (in a wide sense; perhaps the term elegance is more apt) is a cue for truth in mathematical problem solving and scientific discovery.
The theory and its implications have influenced theory and research in the psychology of perception, cognitive psychology, social psychology, empirical aesthetics, web design,  marketing, finance, and archeology.
- Reber, R., Schwarz, N., Winkielman, P.: "Processing fluency and aesthetic pleasure: Is beauty in the perceiver's processing experience?", Personality and Social Psychology Review, 8(4):364-382.
- Winkielman, P., Schwarz, N., Fazendeiro, T., & Reber, R. (2003). The hedonic marking of processing fluency: Implications for evaluative judgment. In J. Musch & K. C. Klauer (Eds.), The Psychology of Evaluation: Affective Processes in Cognition and Emotion. (pp. 189-217). Mahwah, NJ: Lawrence Erlbaum.
- Schwarz, N., & Clore, G. L. (2007). Feelings and phenomenal experiences. In E. T. Higgins & A. W. Kruglanski (Eds.), Social Psychology: Handbook of basic principles (2nd ed., pp. 385-407). New York: Guilford.
- Berlyne, D. E. (1971). Aesthetics and psychobiology. New York: Appleton-Century-Crofts.
- Birkhoff, G. D. (1933). Aesthetic measure. Cambridge, MA: Harvard University Press.
- Martindale, C., & Moore, K. (1988). Priming, prototypicality, and preference. Journal of Experimental Psychology: Human Perception and Performance, 14, 661–670.
- Schwarz, N. (2006). On judgments of truth & beauty. Daedalus, 135, 136–138.
- Reber, R. Brun, M., & Mitterndorfer, K. (2008). The use of heuristics in intuitive mathematical judgment. Psychonomic Bulletin & Review, 15, 1174-1178.
- Topolinski , S. (2010). Moving the eye of the beholder: Motor components in vision determine aesthetic preference. Psychological Science, 21, 1220-1224.
- Opacic, T., Stevens, C., & Tillmann, B. (2009). Unspoken knowledge: Implicit learning of structured human dance movement. Journal of Experimental Psychology: Learning, Memory and Cognition, 35, 1570–1577.
- Rubin, M., Paolinia, S., & Crisp, R. J. (2010). A processing fluency explanation of bias against migrants. Journal of Experimental Social Psychology, 46, 21–28.[View]
- Plumhoff, J. E. & Schirillo, J. A. (2009). Mondrian, Eye Movements, and the Oblique Effect. Perception, 38, 719–731.
- Thielsch, M. T., & Hirschfeld, G. (2010). High and low spatial frequencies in website evaluations. Ergonomics, 53, 972-978.
- Thielsch, M. T., & Hirschfeld, G. (2012). Spatial frequencies in aesthetic website evaluations – explaining how ultra-rapid evaluations are formed. Ergonomics, 55, 731-742.
- Lee, A. Y., & Labroo, A. A. (2004). The Effect of Conceptual and Perceptual Fluency on Brand Evaluation. Journal of Marketing Research, 41 (2004): 151–165.
- Labroo, A. A., Dhar, R., & Schwarz, N. (2008). Of frogs, wines, and frowning watches: Semantic priming, perceptual fluency, and brand evaluation. Journal of Consumer Research, 34, 819-831.
- Alter, A. L.; Oppenheimer, D. M. (May 2, 2006), Predicting short-term stock fluctuations by using processing fluency (PDF), p. 4
- Hodgson, D. (2009). Symmetry and humans: reply to Mithen's 'Sexy Handaxe Theory'. Antiquity, 83, 195-198.
- Gazzaniga, M. S. (2008). Human: The Science Behind What Makes Us Unique. New York: Ecco Books, Harper Collins.
- Song, S., & Schwarz, N. (2010, February). If it's easy to read, it's easy to do, pretty, good, and true: fluency effects on judgment, choice, and processing style. The Psychologist, 23, 108-111. 
- A PowerPoint presentation on the processing fluency theory of aesthetic pleasure
- Improving Graphical Design - A practical guide how to use processing fluency to enhance graphical design.