How Our Brain Judges Real From Fake

In this essay for our new exhibition FAKE, Fiona Newell, professor of psychology at Trinity College Dublin and one of the curators of the exhibition, talks about the brain's ability to judge real from fake. 

Fake is defined as ‘not genuine, an imitation or counterfeit’ and we often pride ourselves on being able to rapidly tell when something is not real. In fact, recent research in human perception has suggested that we can reliably categorise fake versions from the real when looking at food, flowers or fruit from just the briefest exposures to those images i.e. 40ms — less time than it takes the eye to move over an image.

Our recognition of ‘fake’ can even elicit an emotional response: we often recoil when an actor puts on a fake Irish accent; the size of the market for fake tan can trigger surprise; and we may even be secretly impressed by efforts to forge money or art. Furthermore, we can readily produce fake responses as required in certain social situations — think of how often we produce a radiant smile when presented with an unsuitable gift, a calm demeanour during a stressful interview or a belly-laugh to a joke we just didn’t get.

Although our current knowledge of the neuroscience behind the detection of fake from real is poor, we are slowly building up a better understanding of the brain and behavioural processes underpinning this ability. Over the years, together with my research group and collaborators, we have attempted to provide a better understanding of how our senses contribute to the perception of our world.

In the context of this exhibition, FAKE, interesting scientific questions arise. We wonder what senses contribute to our ability to discriminate real from fake, and whether some senses are more reliable than others. Or, to put it another way, do the sensory regions of our brains respond differently when something is real, i.e. physically true or objectively exists, compared to when something is fake? If so, how is this associated with our ability to perceive real from fake, and what are the limits of this ability?

If we think about detecting the difference between real and counterfeit banknotes, we might think that our senses play only a small role in discriminating between them, since such a task may rely more on attention and memory, i.e. our ability to notice and remember the appearance of bank notes (would you know without looking which architectural feature appears on a €10 note?)

Even if we are highly familiar with the visual features associated with each banknote, research on the limits of visuo-spatial attention suggests that our ability to detect a real from counterfeit banknote may be hampered, even if both are placed directly in front of you. Indeed, forged banknotes are passed between unsuspecting people every day, causing problems for banks and police alike.

Our research on multisensory processes suggests that perception is enhanced by combining information across the senses — therefore our ability to discriminate, detect and recognise the contents of our world benefits from having access to the look, feel and even sound of an object at any one time. This research hints at how perceptual science might be applied to the better design of high-value products, thus thwarting the skills of master counterfeiters.

Our brain’s ability to rapidly judge what is real from what is fake is also fundamental to our successful interaction within our social world. Our sensory brain is so finely tuned to social information that it has a remarkable ability to perceive subtle changes, such as those between facial or vocal expressions. Yet fake expressions may be more difficult to discriminate from their genuine counterparts. A genuine smile, the so-called ‘Duchenne’ smile, is thought to be characterised by specific movements in facial muscles that are not stimulated during an insincere smile.

However, as scientists, we have learned that our perception of the world cannot always be predicted from measurements of its physical properties — and visual illusions are a nice demonstration of that fact. Rather, perception results from a combination of factors, including the integrity of the underlying biology, the nature of the information itself, and our prior knowledge. In essence, our brain uses all of this information to make probability judgements about what is perceived.

This all leads to the ultimate question: what is FAKE? To be able to perceive real from fake assumes that our brain has a representation, or can estimate the likelihood, of what is real in the first place.

In this exhibition, members of my research group are testing that assumption by measuring the extent to which we perceive our own bodies as ‘real’ in space. We know, for example, that our actions rely on precise judgements of our body position in space, so that we can accurately reach or grasp an object. But how real is our representation of our body? Some illusions, such as the rubber arm illusion, suggest that even our perception of where our bodies are in space can be manipulated.

Our research will help us explain the extent to which our brain provides a faithful representation of our body limbs in space, or whether our body representation changes to each circumstance and, as such, is adaptable — or, to put it another way, fake.

FAKE: THE REAL DEAL? at Science Gallery Dublin is now open, Tuesday-Friday from 12:00 to 20:00 and Saturday and Sunday from 12:00 to 18:00. Visit to find out more.