Category Archives: Seeing

A blind man hallucinating

NPR has an brief but interesting piece on a blind man who has visual hallucinations. Stewart, the person in question, lost his sight due to hereditary sight-loss, but has developed Charles Bonnet syndrome, a curious condition where playful visual hallucinations are common. Two things about this condition are striking: firstly, the hallucinations are typically complex […]

Polanski and the Professor

It was 1970, and a white Rolls Royce was gliding through the streets of London. Inside were the obviously disturbed Roman Polanski, the film director still reeling from the murder of his wife, and Richard Gregory, the legendary cognitive psychologist. Polanski had discovered Gregory’s work on visual perception through his book Eye and Brain and […]

Pulsing visual illusion

Omni Brain has found an op-art style visual illusion that seems to pulse out from the centre. Click on the link below or on the image to get the full picture, and if you don’t see the effect straight away, just glance at the corners. The effect is a slow shimmering movement when it kicks […]

Mind snacks

Exploratorium has a gallery of try-it-yourself perception experiments. There’s plenty of great material here, not least because of the the slightly bizarre photos of people with distracting 80s haircuts. There are quick projects on everything from proprioception to taste, and you can tell which are the good ones because they list ‘adult help’ as one […]

The beauty of false depth

The image is one of many beautiful street art images from artist and architect Kurt Wenner who uses false perspective to give the images an impression of a 3D structure when viewed from a certain angle. Wenner uses the same optical manipulation as Julian Beever, whose work we covered previously on Mind Hacks. It takes […]

Strobing numbers show saccadic vision

This week’s New Scientist has a brief letter which describes an elegant demonstration of visual processing during eye movements. When you move your eyes (known as a saccade), visual input is suppressed, so less information is processed by the brain during the move. This can be easily demonstrated, as described in one of the hacks […]

Artificial intelligence ‘sees’ visual illusion

A study just published in PLoS Computational Biology has reported that an artificial intelligence system trained to make sense of a simulated natural environment is susceptible to some of the same visual illusions that humans fall for. In one of these, the ‘Herman grid‘ illusion – illustrated on the right, you may be able to […]

Illusory motion with waves of almonds

I’ve just found a visual illusion that gives a striking impression of motion from a static image. It’s entitled ‘this picture is not animated’, which, like anything eye-catching on the internet, immediately made me check whether it was or not. With many of these sorts of illusory motion images, you can ‘stop’ the motion by […]

Pink slip, feeling blue

Ben Goldacre over at Bad Science has written a great analysis of a recent study that suggested we have the traditional ‘pink for girls, blue for boys’ because of evolutionary differences in colour preference. However, it seems not only are the study’s findings not strong enough to make an evolutionary claim, but that the ‘pink […]

Spinning silhouette illusion

I’ve just found this ‘spinning silhouette‘ visual illusion which took ages to take effect but when it did it was so striking I thought at first it was faked. The idea is that you keep looking and the woman suddenly ‘flips’ and seems to spin in the opposite direction. It’s very impressive when it happens, […]

An artistic impression of alcoholic delirium

The picture is from this month’s British Journal of Psychiatry and is entitled ‘Memory image of acute alcoholic delirium’. It was included in a 1919 book of cases studies of people with alcoholic delirium, otherwise known as delirium tremens or the DTs, and was drawn by a patient to communicate their hallucinatory experiences. Delirium is […]

Striking perspective shift illusion

I’ve just stumbled across a remarkably simple yet fiendishly effective visual illusion that seems to give flat images the illusions of 3D depth. It works by quickly shifting between two images of the same scene taken from slightly different perspectives. As we’ve noted when discussing other illusions, our brain generates the experience of seeing a […]

Single gene gives mice new sense of colour

The journal Science reports a study showing that mice given a single gene can develop full colour vision. Mice, like most mammals except primates, are normally colourblind. The implanted gene, which is found in humans, is responsible for making a photopigment, a light-sensitive protein in the photoreceptors of the eye. The researchers from the Howard […]

Movies and the McGurk Effect

HacksZine is hosting a video by Brian Sawyer who riffs on the Mind Hacks book entry on the McGurk Effect and shows how this is used in movies. The McGurk effect is, for example, where when you hear the sound of someone saying ‘Ba’ at the same time as you see them saying the sound […]

Faces, faces everywhere

The New York Times has a brief article on why we have a tendency to see faces in chaotic or almost random visual scenes. The tendency to see meaning in essentially random data is variously known as apophenia or pareidolia, and statistically would be known as a Type I error – a false positive. Although […]

Beauty and the average girl

Flickr user Pierre Tourigny has created a series of composite images from popular portrait rating website Hot or Not? that nicely demonstrates our bias for perceiving average faces as beautiful. He’s made average images from a series of female faces but divided them up into the scoring categories, so there’s an average of faces rated […]


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