Science Book a Day Interviews Clive Gifford and Anil Seth


Special thanks to Clive Gifford and Anil Seth for answering 6 questions about their recently featured book – Eye Benders: the science of seeing and believing

Clive Gifford is a highly experienced journalist and author with over 150 books published and more than 800 features and stories written for adults and children. Clive is an unusual author who likes to work in both fiction and non-fiction. Perhaps this reflects his unusual life which, so far, has seen him travel to over 70 countries, be held hostage in Colombia, go parachuting, coach several sports and run a computer games company. – From Clive’s Homepage

I lead multidisciplinary research across neuroscience, psychology, and computer science, with a focus on understanding the biological basis of conscious experience – a key challenge for 21st century science. Via the Sackler Centre we emphasize the application of our research in the clinic through psychiatry and neurology. And we also develop statistical methods for identifying causal interactions in neural systems. – From Anil’s Homepage

Clive’s Homepage:

Anil’s Homepage:
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#1 – What was the impetus for Eye Benders? Who is it aimed at?

[Anil] Clive best to answer this. But from my perspective its great to make neuroscience accessible, and to show how wonderful the apparently effortless phenomenon of ‘seeing’ really is.

[Clive] We felt that although there are quite a lot of optical illusion books out there already, very few of them made any great efforts to answer the key questions of how and why each illusion works. Books for children on the subject were especially culpable – often being just a gallery of illusions without any explanation. I was delighted when Hazel Songhurst and Georgia Amson-Bradshaw of the publishers, Ivy Kids, indicated that they wanted much more from Eye Benders. I was very keen on showing as much of the varied range of illusions as possible to get across to readers how there are a surprisingly wide range of different ways that our brains and sense of vision trick us or fall short. But also to use the illusions as a stepping stone to explaining some of the more fascinating aspects of our brains and vision systems. It meant a lot more hard work but proved fascinating. The book was written for children but from some of the road testing of spreads I conducted with friends’ families, it quickly became obvious that adults were just as fascinated in how the illusions worked as much as their offspring.

#2 – Visual illusions have been around for some time. Can you give a brief (might be hard) explanation of how illusions work?

The history of visual illusions indeed dates back to the Greeks. Aristotle had something to say about them, as did Plato – these debates tended to revolve around whether the senses or the environmental were responsible for the ‘deceit’. Today, the prevailing idea is that optical illusions reveal the ‘faultlines’ in how the brain constructs perceptual scenes from the inherently ambiguous sensory signals that impinge on our sensory organs. The German physiologist and psychologist, Hermann von Helmholtz, was among the first to think of perception as a process of ‘unconscious inference’. This means that our perceptual experiences are the brain’s ‘best guess’ of the causes of sensory signals. This in turn means that the brain has (unconscious) assumptions about the relations between these causes and the sensory signals it receives. Optical illusions play on these assumptions to reveal some striking effects. For instance, the brain assumes that things get smaller as they get further away, and that light generally comes from above. Both these ‘assumptions’ can lead to strange illusions, as Clive shows in the book.

Illusions are still, today, playing key roles in cognitive neuroscience, since they allow us to tease apart brain processes that correlate with sensory input, from those that correlate with perceptual experience.

#3 – You feature each illusion on a double page with different examples. How did you source these examples? What is the oldest illusion you have in the book?

It came down to stacks and stacks of research and reading: books, journals, websites, academic papers and magazine articles as well as great suggestions from Anil. We quickly learned that there are some ‘classic’ or ‘ideal’ examples of a particular illusion type – leaders in their field such as the Kanisza Triangle illusion and, in terms of illusions based on perspective, the Ames Room (on pages 40-41 in our book). It felt remiss not to include these, but there was still plenty of space and opportunity to include some illusions or variations on illusions that were not so well known or were the results of more recent research. The book’s editor, Claire Saunders, was exceptional in contacting institutions and artists where we were are after a particular illusion and as a result I really think we managed to assemble a broad and varied collection of illusions.

I have to say that I am not certain which is the oldest optical illusion featured in the book. It may be that the forced perspective illusions have the longest history as the Ancient Greeks are known to have played with perspective in some of their architecture.

#4 – Some illusions that rely on scale might be easy to explain. Has it been difficult to explain the trickier ones? Are there any illusions where we don’t know how they work??

I think Clive did a great job of explaining some of the more counterintuitive illusions. For my money, illusions of colour are particularly challenging – like the ‘colour puzzlers’ on page 30. Partly this is because colour vision involves a lot of processing informed by the overall context of the visual scenes – colours can change appearance depending on other objects, and on overall luminance, and so on. And partly because colour vision is inherently mysterious – even Newton struggled to decide whether colours were ‘real’ or not.

Having said this, the illusions in the book can all be explained at least to some extent. At the same time many illusions – those in the book and others too – continue to deliver important new insights into how the brain generates our conscious visual experiences. And scientists are always coming up with new illusions that challenge our ability to explain them – see – some of these truly escape our current theories!

Anil’s very kind, but I must stress that his input was crucial as was editor, Claire Saunders, in ensuring that the explanations remained clear and not overlong. I never wanted to bog down the readers in vast amounts of scientific detail. This was not the purpose of this book. I think the first thing we wanted to convey was that most illusions don’t just pop up of their own accord or occur in a vacuum – they are a result of our brains, senses and processing, so the aim was to use the illusions as a way of detailing some key aspects of how we see, how we perceive and how we process signals from our eyes.

#5 – What has been the reaction to your book? From the public? Kids? Scientists?

[Clive] Even if you are proud of all the efforts put into a book, you never quite know what the reaction will be when it is published and released into the wild. I’ve been writing books for children for almost 30 years but have been stunned by the rave reviews and readers’ letters I have already received. People really seem to have appreciated our attempts to give a little bit of science underpinning to the great illusions they view. It’s very gratifying.

We recently received the wonderful news that Eye Benders has been shortlisted for the highly prestigious Royal Society Young People’s Book Prize. This is pretty much the biggest honour a children’s science book can obtain in the UK so we’re absolutely delighted. The winner will be announced by the President of the Royal Society (and Nobel Prize winner) Sir Paul Nurse at a ceremony in November this year so we all have our fingers crossed and I’m trying to lose weight to fit into my one suit to attend! But, to be honest, just to be nominated is a great honour and more than repays the efforts put in to create the book.

#6- Are either of you working on new books/projects?

[Anil] Yes! Brain Twist. Clive can explain!

[Clive] Yes. I was delighted when Ivy commissioned Brain Twists with Anil as consultant. The old band has been put back together! This will be in a similar format to Eye Benders but will be focusing on aspects of the human brain and how it works. Like Eye Benders, it will feature activities, experiments and ‘tricks’ that brains play on people as a springboard to conveying some of the brain’s extraordinary complexity and range of function. We’ll be looking at how the brain interprets data from our wide range of senses, how decisions are made and influenced, the role of emotions, memory and attention and many other things besides. It’s going to be an exciting ride and I cannot wait to get writing it over the summer.

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