Wider than a page

You should have noticed from the exercise at the end of the previous chapter that your peripheral vision is very wide. When working vertically, did the hand above your head disappear closer than the one below? This is usually the case as your brow gets in the way.

It makes sense that we have a wider field of vision horizontally as our eyes are arranged side by side on our heads rather than one above the other. From an evolutionary point of view, it was important for our hunter-gatherer ancestors to be sensitive to potential predators such as sabre-toothed tigers stalking them from either the left or right. It was far less likely that they would be attacked from above by an eagle swooping down from the sky.

If you look at a rabbit’s eyes, you will notice that they are on the sides of its head. This gives it almost 360-degree vision. Rabbits are very vulnerable to predation by foxes, cats, dogs and even weasels and ferrets, so need to react very quickly to run from danger. On the other hand, predators’ (such as cats’) eyes face forward, offering a wide field of overlapping sight. In the area of binocular vision, depth perception and distance assessment their vision is greater than any other carnivore’s, which contributes to their remarkable hunting skill. However, a fearful cat’s pupils will be fully dilated to create a wider field of vision and take in as much of the surroundings as possible.

The fact that your field of vision is much wider than a page has important consequences for reading.

The science of seeing

The optics of your eye act a lot like a camera. Light initially passes through the cornea, a clear cover that protects the eye, before entering through the pupil, an opening a little like a camera’s aperture. The iris regulates pupil size. This is the coloured part of the eye that expands and constricts to allow more or less light in. It is interesting that the iris not only responds to intensity of light but it also reacts to emotions. If you see something interesting or attractive your iris will constrict to widen your pupil. Chinese jade traders used this fact to gauge customers’ interest in particular stones and hence quote an appropriate price.

Once light has passed through the pupil it enters the lens. This changes shape to focus nearby or distant objects upside down on the retina, a series of light-sensitive cells lining the back of the eye. These are predominately of two types: the rods and cones. Rods function mainly in dim light and provide black-and-white vision, while cones support daytime vision and the perception of colour. Cones are more densely packed in the centre of the macula region of the retina in a small pit called the fovea. This is responsible for sharp central vision, necessary for reading. If an object is large and thus covering a large angle, the eyes must constantly shift their gaze to subsequently bring different portions of the image into the fovea (as in reading with a book close to your eyes).

Although I have used a camera analogy this is far from the reality of how the eye and brain work in combination with each other. Seeing takes place primarily in the brain. The visual cortex at the back of the brain is divided into regions that specialise in processing different aspects of the image. What the eyes actually deliver is a very sharp, coloured central image with less sharp but very wide peripheral vision. This includes two ‘holes’ that correspond to the blind spot where the optic nerve joins the retina in each eye and where there are no photoreceptors. The brain fills in the blanks and gives us a perception of the world. Most so-called ‘optical’ illusions actually occur in the brain rather than the optics of the eyes. Segall et al. (1966) found that people from Zulu tribes were unable to perceive the Müller-Lyer illusion, devised by the German sociologist in 1889 (see Figure 5.1 below). This is probably because their visual environment contains few rectangles, straight lines and regular corners and so their brains are not sensitised to these.

When you consider what an amazing job the brain does with limited information, you shouldn’t worry about missing the odd word when reading!

So what does this practically mean for reading?

One consequence of the eye’s optics is that, if you hold a book, or digital device, too close to your eyes, you are not making the most of your visual system.

Imagine holding a book a couple of centimetres from your eyes, almost touching your nose. You will just about be able to focus on it and see perhaps one or two words.

Now imagine the book at a typical distance of about 20 centimetres. You have no trouble focusing on the page but because the book is further away the text appears smaller. A larger area of the page is projected onto the central area of your retina by the eye’s optics. You will hence be able to read groups of words.

Finally, if you hold the book at a distance of 50 centimetres you can focus on a much larger area of the page and still see it clearly. Taking in groups of words is far easier and you will be able to take in larger ‘visual gulps’. Because of the increased distance of the book, the eyes have to move far less to track across the width of the page. The geometry makes a great improvement to all areas of focused reading.

If you find it uncomfortable to hold your arm out when reading, especially if you have a heavy book, you can use a bookstand (often sold for recipe books) or even a music stand. If you are reading using an iPad the cover can be folded so that it will stand upright without the need to physically hold it.

What use is peripheral vision?

It is remarkable to think of the ramifications of something as simple as holding the book at a greater distance, but it doesn’t stop there. Holding the book at arm’s length has the secondary benefit that your peripheral vision is able to work more effectively.

Although not in sharp focus, your peripheral vision still gives your brain useful information. You need your central focus to read each group of words, but peripheral vision can identify paragraph structure, layouts, large headings, the position of illustrations and even some words, as we will see in the exercise at the end of this chapter.

Of the 130 million photoreceptors in each eye, over 80 per cent are devoted to peripheral vision. Have you ever been reading one column of a newspaper or book and noticed that there is a particular word elsewhere on the page or even on the opposite page? You have a sense that it is there but then have to hunt to find it. It will be something important to you that your peripheral vision has spotted and to which your subconscious has been alerted.

Comprehension is improved if you have a general idea of the structure of a page. The main headings and paragraph structure helps create a framework into which the detail is placed. As your peripheral vision can easily take in a whole page, it acts as a scout, previewing what is coming up and helping to provide this framework before you read with your central focus. It gives your brain a starting point upon which to build meaning.

Peripheral vision not only lets you ‘see ahead’ but also you literally ‘re-view’ what you have just read. Reviewing is one of the prime keys to memory so making use of peripheral vision also helps you remember what you read.

Another added benefit is that you do not have to focus so hard. This can reduce some of the most common ailments associated with reading such as fatigue, eyestrain and headaches. Holding the book at a distance will help you avoid hunching forward or bending your head down to read. Bad posture and neck stress are almost guaranteed to cause neck and back pain and reduce your focus, concentration and the amount of time you can read.

As well as taking in groups of words on a single line you will eventually find that your focused vision is able to take in more than one line at a time. This may sound counterintuitive but when you consider just how much processing the brain does merely to see an image, it is not unreasonable to expect it to make sense of bigger chunks of information. Each group of words works like a jigsaw piece that the brain slots together to make sense of the text. Using a pointer to guide the eyes facilitates this process. We will cover guiding in detail in Chapter 7.

Try to make sure that your reading material is as clear as possible. Avoid old, cheaply printed books where the paper has oxidised and gone yellow. With eBook readers, go for the largest and clearest display you can. Apple’s ‘Retina display’ on the new iPad has 3.1 million pixels, so close together that your eyes can’t discern individual ones at a normal viewing distance. Try to read in natural daylight or, if this is not possible, position a light shining over the shoulder opposite the hand you write with to avoid glare and shadows. Try not to have a big difference between overall illumination in the room and lighting of your desk or reading area.

STOP YOUR TIMER NOW (word count 1,826)

Comprehension questions

1. Is your field of vision greater horizontally or vertically, and why would this make sense in terms of evolution? [2]
2. Which light-sensitive cells in your retina are responsible for colour vision and where are they most densely packed? [2]
3. How far away from your eyes should you hold a book? [1]
4. What percentage of the photoreceptors in your eyes is responsible for peripheral vision? [1]
5. Name three benefits of using peripheral vision. [3]
6. With practice, focused vision can take in more than one line at a time. True or False? [1]

Check your answers in Appendix 1.