Category: Perception

A psychologist noticed this cool chair illusion in his office

10.1177_2041669517752372-fig1.gifBy Alex Fradera

A short paper in the journal i-Perception presents a disconcerting visual illusion spotted “in the wild”: how stackable chairs, viewed from a certain angle, mess with your head. This is an unedited image, but your mind resists accepting it could be real. The illusion was first noticed in the office of lead author Nick Scott-Samuel at the University of Bristol, who notes in the paper that “it obtains in real life as well as in images, even when sober”.

The cause of the trick appears to be the two “edges” seen coming up from the near-base of the stack – marked AD and BC in the annotated version of the image below – which “suggests a change in depth along those lines which does not actually exist” and makes it seem as if the bars that run from one “edge” to another compose an outward face.


160px-Penrose-dreieck.svg.pngIt misleads us a little like the Penrose triangle (see right), but whereas the triangle is actually impossible, the chairs only appear to be so – as demonstrated in this video where you can see the effect dip in and out. Scott-Samuel and his colleagues experimented with the chair stack and it appears that you need at least four chairs to create the effect.

You know the angles, you know the number: turn up to the meeting room early next time and use that recipe to astound even the most jaded eyes.

Stacking Chairs: Local Sense and Global Nonsense

Alex Fradera (@alexfradera) is Staff Writer at BPS Research Digest

Different psychiatric symptom dimensions have opposite associations with confidence and metacognition


Screenshot 2018-01-29 17.44.58.png
Decision accuracy was unrelated to symptom dimensions, but confidence and metacognition were. Figure via Rouault et al

By Christian Jarrett

Some researchers hope that focusing on the cognitive, neural, genetic and social processes that contribute to symptom dimensions – like anxiety-depression or social withdrawal – may be more fruitful than trying to understand the causes of different diagnostic categories, like “schizophrenia” or “major depression”. It’s in this vein that a new paper in Biological Psychiatry has used a simple perceptual task to investigate how judgment confidence, judgment accuracy and metacognition (judgment insight) are related to various trans-diagnostic symptom dimensions in the general public.

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There’s an evolutionary explanation for why we’re surprisingly bad at recognising each other’s laughter

GettyImages-667207606.jpgBy Alex Fradera

We have a mostly impressive ability to identify people we know based on the sound of their voice, but prior research has uncovered an intriguing exception – we’re not very good at discerning identity from laughter. Now Nadine Lavan and her colleagues have published research in Evolution and Human Behavior that looks into why this might be and what it says about our evolutionary past.

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There may be a sense in which expert athletes see things in slow motion

GettyImages-543894324.jpgBy Christian Jarrett

Experienced sports players aren’t just highly skilled at executing their own actions, they also have what often seems like a supernatural ability to read the game, to watch other players and anticipate what’s going to happen next. A clever new study in Psychological Research offers insight into the brain basis of this aspect of sporting ability – the findings suggest that expert basketball players simulate in their minds the actions of other players in something akin to slow-motion, presumably giving them more time to interpret and read the actions.

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Believers in conspiracy theories and the paranormal are more likely to see “illusory patterns”

GettyImages-177765632.jpgBy Emma Young

Democratic bankers caused the global financial crisis to get Barack Obama elected. 

Horoscopes are right too often for it to be a coincidence. 

Irrational beliefs – unfounded, unscientific and illogical assumptions about the world – are widespread among “the population of normal, mentally sane adults” note the authors of a new study in European Journal of Social Psychology. It’s been proposed that they arise from a mistaken perception of patterns in the world. But though this idea is popular among psychologists, there’s been surprisingly little direct evidence in favour of it. The new work, led by Jan-Willem van Prooijen at the Free University of Amsterdam, helps to fill the void.

Continue reading “Believers in conspiracy theories and the paranormal are more likely to see “illusory patterns””

Mentally well voice-hearers have a heightened ability to detect real speech


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(A) Averaged brain activity in response to intelligible speech in control participants and (B) in non-clinical voice hearers; from Alderson-Day et al, 2017

By Emma Young

Hallucinating voices isn’t always distressing. While the experience is commonly associated with schizophrenia, some people – an estimated 5 to 15 per cent of the general population – hear voices that aren’t real without finding it upsetting or debilitating (they may even welcome it) and in the absence of any of the other symptoms of psychosis, such as delusions or confusion.

Now new open-access research published in Brain has revealed a perceptual advantage for this group of people: they can detect hard-to-comprehend speech sounds more quickly and easily than people who have never hallucinated a voice.

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The idea that humans have a poor sense of smell is an outdated myth, argues new review

The Nose For Wine
It’s estimated that humans may be able to distinguish up to a trillion different smells

By Alex Fradera

In the early 1950s, while investigating rabbits’ sense of smell by recording the activity of their brain cells, the scientist Lord Adrian noticed something curious. As his team mixed up odours of increasing strength, to see at what point the rabbits’ neurons fired in response, they found the critical threshold appeared around the same point that they were able to smell the odour themselves: in other words, this suggested that the smell had become noticeable to animal and man at the same time.

On publication of the research, Lord Adrian mentioned his observation, but it didn’t provoke a serious response, presumably because informed scientists knew that the human sense of smell is generally pathetic. Everyone knew… but they knew wrong. In a new review in Science, John McGann, who runs the Rutgers Laboratory on the Neurobiology of Sensory Cognition, takes us through the historical misunderstandings to reach the truth about what the human nose knows.

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These nine cognitive psychology findings all passed a stringent test of their replicability

By Christian Jarrett

The failure to reproduce established psychology findings on renewed testing, including some famous effects, has been well-publicised and has led to talk of a crisis in the field. However, psychology is a vast topic and there’s a possibility that the findings from some sub-disciplines may be more robust than others, in the sense of replicating reliably, even in unfavourable circumstances, such as when the participants have been tested on the same effect before.

A new paper currently available as a preprint at PsyArXiv has tested whether this might be the case for nine key findings from cognitive psychology, related to perception, memory and learning. Rolf Zwaan at Erasumus University Rotterdam and his colleagues found that all nine effects replicated reliably. “These results represent good news for the field of psychology,” they said.

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Having an open-minded personality manifests at a basic level of visual perception

Rene Descartes' diagram of the human brain and eye, 1692.By Christian Jarrett

Openness to Experience is one of the so-called Big Five personality traits and, among other things, it’s associated with being more creative, curious and appreciative of the arts. Like all the traits, where you score has important implications – for instance, there’s recent evidence that being more Open is associated with having more “cognitive reserve”, which gives you protection from the harmful effects of dementia.

Openness correlates with, but is distinct from, intelligence, and psychologists are trying to find out more about what the basis of Openness is at a cognitive and neural level. A new paper in Journal of Research in Personality shows that the trait runs deep, even affecting a very basic aspect of visual perception. It seems Open people literally see the world differently.

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Neural changes after taking psychedelic drugs may reflect “heightened consciousness”

Girl's Portrait With Crazy Hair - Lifestyle Concept.By Emma Young

Is there anything psychedelic drugs can’t do? A recent wave of scientific scrutiny has revealed that they can elicit “spiritual” experiences, alleviate end-of-life angst, and perhaps treat depression – and they might achieve at least some of all this by “heightening consciousness”, according to a new paper published in the journal Scientific Reports.

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