My life has changed in many ways since the start of the Coronavirus epidemic. Take, for example, how I relate to people in the street. Over the last nine months I have developed the keenest of eyes for spotting fellow pedestrians who are, or will be, too close for comfort.

In one circumstance, however, detection is difficult – it is a very different challenge when someone comes up from behind. This is a problem I have been working on and, although I can’t see all round like any decent footballer (see illustration), things are certainly getting better. First an ill-defined image appears in the corner of my eye. Then the image evolves into something I can identify – a jogger or a cyclist. Finally, and if I am lucky, I have time to turn my head away as they pass by exhaling trouble.

There is, however, always the possibility that such images are figments of the imagination and, with the heightened levels of anxiety associated with the pandemic, this seems possible. It is these corner-of-the-eye views – sometimes false and sometimes true – that prompted me to write this blog.

Sight is the most extraordinary of our senses. Compared with smell, touch, taste and hearing, the eyes are unmatched as they can tell us by means of precise visual images what exactly is going on close up or at a distance. Such capacity demands an awareness which involves several steps. The lens at the front of the eye focusses light patterns on to the cells in the retina. Information from these activated cells is sent to the occipital lobe. Once there, circuits are stimulated which give us the conscious capacity to see. Well, that is the process at its simplest, but there are other parts of the brain that have an input too.

Let me describe two phenomena; first visual inattention. On occasions we simply fail to see the obvious. In a now classic study, audiences were asked to watch a short film showing two teams of people walking around in a circle and throwing balls to their team mates. At one point in the film a ‘gorilla’ strolls amongst the players.

How audiences perceive what happened varies. Some spectators are asked beforehand simply to watch and report what they see; of these, all comment on the incongruous appearance of a gorilla. In contrast, other spectators are instructed to concentrate on, and count, how many times members of a particular team catch their ball. In this group, more often than not the gorilla goes unnoticed. Clearly, the mind can choose what it wants to see!

Now to the phenomenon of blindsight. It is now known that objects can sometimes be ‘seen’ by people who are otherwise blind. As a result of severe damage to their occipital lobes, such people have no conscious awareness of what is happening in front of them. Despite the damage some will take evasive action if challenged by something threatening such as an oncoming stone. For this to happen there has to be a section of the brain apart from the occipital lobe that can process what arrives on the retina. Accordingly, ‘seeing things’ does not rely entirely on there being a conscious element.

Examples of where the subconscious plays a part in how we see things are probably commonplace; here are just two – one comes from my sister, the other is mine.

Sarah is a renowned textile designer. When she has all but finished a design she will pin it on the wall away from her studio table ‘to let it settle’. While working, the design would be ‘under her nose’ and the focus of her attention. For a few days she will now see the design more in passing – ‘out of the corner of my eye’, as she says. In this less-focussed period imbalances will often reveal themselves and so suggest to her where the design might be improved. She believes that with the design at a distance her mind is able to work on what she has done at a subconscious, more intuitive, level.

The second example involves Wendy, a young researcher who worked along the corridor from my office at St George’s Medical School. She was very slim and always wore a long-sleeved black T-shirt and black tights. To set these off her face was powdery white. We were on nodding terms and one morning, out of the corner of my eye, I caught sight of her in her lab. As I walked by I said my good mornings but unusually there was no reply. I repeated my greeting and again silence. Puzzled, I turned around to discover that what I had taken to be Wendy was a five-foot tall oxygen cylinder with its standard colour-coding – white top and long, slim black body!

The corners of our eyes provide us with a wonderful service. Any subconscious element should be embraced, even celebrated.

The illustration shows a picture of the Manchester United player Marcus Rashford who at full speed is dealing with two opponents seen only out of the corners of his eyes.

For helping me write this blog, I would like to thank Sarah, Tom, Rohan and Vivien.