Presented with these two semantically identical statements, people will believe the top one more than the bottom one. Why is this? And what does it tell us about John Keats' famous dictum about beauty and truth?


Osorno is a city in Chile. This statement is a fact. But not everyone is familiar with Osorno's municipal and/or geographical status. And, it turns out, if you present people with this statement written in blue, more of them will judge it as truthful than if you present it written in yellow. Why is that?

The answer boils down to something psychologists call processing fluency, i.e. the ease with which we mentally process information. In recent decades, several investigations have revealed that fluency plays a subconscious role in many of the conclusions we draw about the world around us. Judgements of truth, required effort, physical proximity, and even the performance of the stock market have been shown to be affected by how easily we process information about the thing being evaluated.


"If it's easy to read," summarize psychologists Hyunjin Song and Norbert Schwarz, in an article describing the role of fluency in our choices and day-to-day appraisals, "it's easy to do, pretty, good, and true."

Take the above statements about Osorno, for example. In a 1999 study published in the journal Consciousness and Cognition, Schwarz and another psychologist by the name of Rolf Reber demonstrated that the ease with which we read a statement has a significant effect on our perception of its truthfulness. A statement presented in a highly visible, dark-blue font against a white background is read and processed more readily than one that appears in a less-visible yellow font. The researchers report that, in their study, moderately visible statements, like ones written in yellow, were judged as true at chance level. Highly visible statements, on the other hand, like the ones written in dark blue, were judged as true "significantly above chance level."

Perceptual fluency, in other words, affects our judgments of truth.

Familiarity and the (Illusory) Truth Effect

In an e-mail to io9, Reber, now a professor of cognitive psychology at the University of Oslo, elaborates on this finding. A simple font, he explains, can be read with ease; it follows, therefore, that "messages written in fluent fonts" would be "judged as being more probably true," he explains.


But another quality that affects fluency is familiarity. "If someone has encountered a font often, they can more easily read it," writes Reber, "which makes messages more persuasive."

The effect of familiarity on judgments of truth has been well-documented by a line of studies extending all the way back to 1977, when it was first reported by psychologists Lynn Hasher, David Goldstein, and Thomas Toppino. The researchers described their investigation, and their findings, in the Journal of Verbal Learning and Verbal Behavior:

Subjects rated how certain they were that each of 60 statements was true or false. The statements were sampled from areas of knowledge including politics, sports, and the arts, and were plausible but unlikely to be specifically known by most college students [Ed. Note: For example: "Kentucky was the first state west of the Alleghenies to be settled by pioneers" (true), or "Zachary Taylor was the first President to die in office" (false)]. Subjects gave ratings on three successive occasions at 2-week intervals. Embedded in the list were a critical set of statements that were either repeated across the sessions or were not repeated. For both true and false statements, there was a significant increase in the validity judgments for the repeated statements and no change in the validity judgments for the non-repeated statements. Frequency of occurrence is apparently a criterion used to establish the referential validity of plausible statements.


Ever since, psychologists have used "The Truth Effect" – or, more accurately, "The Illusory Truth Effect" – to describe the phenomenon by which a repeated statement is judged as more likely to be true, by virtue of its reiteration alone. Saying something over and over doesn't make it true — but to our brains, it can certainly seem that way.

What Else Does Processing Fluency Influence?

Part of what made Reber and Schwarz's colored-text study so innovative was that it hinged not on familiarity but the ease with which unfamiliar statements could be read, prima facie. Their observations provided evidence that familiar things are perceived as true not due to their familiarity as such, but due to processing fluency. Since then, processing fluency has been shown to have a hand in all manner of human judgments about the world.


Consider, for example, a 2005 study by psychologists Daniel M. Oppenheimer and Adam Alter – both, then, of Princeton University. The aim of their investigation was to test the effects of fluency on perceptions of distance. The researchers assigned volunteers at a train station in West Windsor, New Jersey to either a disfluency condition or a fluency condition. Test subjects assigned to the disfluency condition were administered questionnaires printed in 12-point, italicized Haetenschweiler (a bold, sans-serif typeface often compared to Impact):


In contrast, test subjects assigned to the fluency condition were given questionnaires printed in the ubiquitous Times New Roman typeface (also at 12-point, but unitalicized):


The questionnaires asked test subjects to estimate their distance from 24 U.S. cities (for each city, the questionnaire asked: "How far are you from [city name]?]").

"Participants who experienced disfluency estimated that the cities were farther away... than did participants who experienced fluency," the researchers report in Psychological Science. "These results suggest that people use visual fluency as a proxy for distance estimates."


Intriguingly, this observation applied not only to test subjects' valuation of physical distance, but psychological distance. In a supplemental study, test subjects asked to provide a short description of New York City were found to do so in more abstract terms (e.g. "New York's lights, shimmering in the foggy sky, remind me of outer space") than concrete ones (e.g. "New York City is a large city with five boroughs and about 18 million people'') when they received an otherwise identical questionnaire printed in a difficult-to-read font. This finding dovetails with a psychological concept called construal theory, which suggests people construe distant objects and events more abstractly than they do ones that are close to them – be it physically, temporally, or socially.

Taken together, Alter and Oppenheimer write, these two studies "suggest that greater disfluency implies greater distance from a target and leads participants to perceive the world more abstractly."


Does Beauty = Truth?

I've placed a disproportionate emphasis on typefaces in this post – in part because typeface manipulation has proven to be a reliable way to modulate the readability of printed text – but the fact is that fluency has been shown to play a role in all manner of valuations. A fun example: In 2000, psychologists Matthew McGlone and Jessica Tofighbakhsh (2000) reported that aphorisms that communicate substantively similar messages are more likely to be accepted as true when they rhyme (e.g. 'Woes unite foes') than when they don't (e.g. 'Woes unite enemies'). In other words, Vitrivius was on to something in The LEGO Movie when he said something is "true, because it rhymes."


The role of fluency in our day-to-day appraisals has been thoroughly and lucidly recounted elsewhere. I recommend this review by Oppenheimer, who has become a leading figure in research pertaining to fluency and human decision-making. Also worth reading is the aforementioned perspective piece by Song and Schwarz. Their overview highlights a study that investigates the role of fluency outside a typographical context, while raising one of the more tantalizing lines of inquiry in the field of fluency research – one that would link perceptual ease to our valuations of beauty and truth (emphasis added):

Our preference for fluently processed stimuli underlies many of the variables known to influence aesthetic experience, from symmetry and figure–ground contrast to the gestalt laws – all of these variables facilitate fluent processing... The same principle is also central to the observation that we prefer prototypical faces over more unusual ones – prototypical faces are easier to process and elicit a more positive affective response... Moreover, this research also sheds light on why scientists and poets alike believe that beauty and truth go hand in hand, despite all the beautiful and elegant theories that landed on the trash heap of science – intuitive judgements of beauty and truth are based on the same input, namely the experience of fluent processing.


I call this line of inquiry "tantalizing," because the theories linking processing experience with perceptions of beauty and truth are very much in their infancy. A series of publications from Reber, Schwarz, and their colleagues – in 2004, 2006, 2008, and 2010 – attempts to establish a framework that links processing fluency to perceptions of beauty and correctness in, for example, mathematical formulas. The most recent of these studies puts forth that processing fluency may be party responsible for things like intuition and so-called "Eureka! moments."

These observations should not be confused, however, with an endorsement of John Keats' famous claim that "beauty is truth, truth beauty." After all, what do processing fluency's negative effects on judgment – the tendency to place more trust in a false statement if it is repeated, for example, or if it rhymes – teach us, if not that human intuition is so often wrong? Cognitive biases and other quirks of human psychology (e.g. the mere exposure effect, a close cousin of the Illusory Truth Effect) are all the evidence you need that Beauty = Truth is a false equation. And if you're still not convinced that Keats was wrong about this much, I highly recommend Philip Ball's essay on the subject, which you can read at Aeon.