Seeing red (lines)

The story about the lady who painted her Kensington townhouse with red-and-white candy stripes to annoy her neighbours - and who has been ordered by the authorities to paint the stripes out - recently caught a lot of people's eyes, mine included.

Why, indeed, is a stripy house so eye-catching? And would anyone have taken any notice if she had just painted it all bright red instead? 

As far as the first question is concerned, there is a surprisingly neat neurological explanation for this. Our strong response to stripes, and particularly stripes with sharp, high-contrast edges, is, on several levels, quite literally hard-wired into our brains.

I found out about the science involved here a little while ago, researching for a book I'm writing which touches on the psychology of vision (and so of architecture), and this came to mind when I heard about this story. It is a really fascinating area.

Edges

"Eyes that do not see", Le Corbusier was fond of saying.  He was right.  You don't see everything that your eyes are pointed at.

The picture of the world that is focused on your retina by your eye contains an awful lot of information, which is constantly being updated.  Your brain doesn't need, and actually doesn't have space to keep, the vast majority of this.  So, in effect, it bins a lot of the picture. In fact, much of the information is quietly chucked away before the signal generated by the light-detecting cells in your retina has even left your eyeball. 

How so? Well, there are nerve-cells in your retina - so-called "ganglion cells" - who do this work by getting excited by some things, and not by others.

Each one of these cells is wired up to a group of photo-receptors in a particular patch of your retina. That patch is called the cell's "visual field": it is the area that it 'sees'.

If the light across all of the visual field is all of the same intensity - all bright or all dark - the cell will shrug its shoulders and stay quiet. What really interests a ganglion cell - what makes it go a bit mental with electrical excitement - is when one bit of its receptive field is lighter/darker than another bit: in other words, if there is a contrast at play. 

There is an explanation of how ganglion cells achieve this edge-detection trick in this Wikipedia passage (and a better one in Basic Vision, a really well-written beginner's guide to the subject), but, in simple terms, all they are doing is dividing their receptive fields into two areas, namely a spot and a surrounding area in the shape of a doughnut, and responding in an opposite way to it being light in one of these two areas to how they do if it is light in the other.

(http://www.cns.nyu.edu/~david/courses/perception/lecturenotes/ganglion/ganglion.html)

The diagram above shows that some cells are wired up so they get excited when it is light in the central spot, but are inhibited when it is also light in the surrounding 'doughnut' ("on-centred" cells). Some behave in the opposite way ("off-centred" cells).  In either case, the cell doesn't fire when there is the same level of light across the whole of its receptive field. This would be the case if the receptive field lined up with, say, an area in the middle of a blank piece of paper. But when the receptive field is aligned with a contrast between light and dark - for example, the edge of the piece of paper - there will be a difference between the centre and the surrounding doughnut, and the cell may get activated, depending on where the edge falls on its receptive field.

The upshot is that much of the signal that gets fed to your brain by the nerve cells in your eyes is information about contrasts - typically, the edges of objects. In other words, at one level, your brain is 'seeing' something like the image at the right, below, and probably using a fair amount of inference to 'fill in' the rest of the picture:

(http://upload.wikimedia.org/wikipedia/en/8/8e/EdgeDetectionMathematica.png)

Thus, in a sense, we can only respond to change in colour or lightness.  Our brain just doesn't react to unchanging blocks of the same colour.  As the great vision scientist David Hubel puts it, when we look at a solid-coloured object, "... our perception of the interior as black, white, gray, or green has nothing to do with cells whose fields are in the interior—hard as that may be to swallow". As Hubel suggests, this finding is, perhaps, a bit disconcerting, as that's not what the experience of vision is like: it feels like we are seeing the whole picture, not just the outlines of stuff.  But that perception is almost certainly just a comforting illusion.

One consequence of this brain architecture is that line drawings are very legible. Cartoonists just draw the edges, which, for the visual brain, are the essential parts of the world. So cartoons are easy to make sense of and tend to grab your attention.

Another aesthetic consequence is that if the eccentric Kensington home-owner had simply painted her house in one solid block of colour - even if that was a bright, garish red - there is a good chance she would have failed to attract much attention. Solid blocks of colour, the research on retinal ganglion cells establishes, cause less activity in the 'early' part of your visual system than areas with lots of contrast. It is almost literally true to say that high-contrast patterns can get on your nerves; at least, they certainly make for more excitement of the nerve cells in your eyes than blocks of colour.

The studies on ganglion cells and receptive fields date from the 1950's.  But the psychological fact just described - that a blank expanse has less impact than a patten - was, it seems, spotted as far back in 1757, by Edmund Burke. 

Edmund Burke - mercurial C18th writer, usually associated with inventing political conservatism, 
but who also wrote a fun, slightly space-cadet-y book about the psychology of aesthetics 
in his yoof ("Philosophical Enquiry into the Origin of  our Ideas of the Sublime and Beautiful") - http://en.wikipedia.org/wiki/Edmund_Burke#/media/File:EdmundBurke1771.jpg

Burke was seeking to identify what the essential ingredients of impressiveness (what he called the "sublime") were. Impressive, awe-inspiring things, Burke observed, were usually big (such as a mountain), often involve uniform repetition (as with the beating of a war drum), and often have the quality of apparent boundlessness (like, say, the heavens). But if that were the case, why should, Burke asked "... a long bare wall ...not be a more sublime object than a colonnade; since the succession is no way interrupted; since the eye meets no check; since nothing more uniform can be conceived?"  

Despite the wall's uniformity, a row of columns will, Burke suggested, tend to be more "grand" than a blank wall of the same size, for in the case of the wall "... the eye runs along its whole space, and arrives quickly at its termination; the eye meets nothing which may interrupt its progress; but then it meets nothing which may detain it a proper time to produce a very great and lasting effect".  Burke's idea here, namely that the human visual perceptual apparatus skips over stretches of blankness and that contrast is required to create an "effect", is exactly what the modern science of vision tells us actually happens inside our heads.

At any rate, the first thing that your visual system picks up about the stripy house is that there are a number of very sharp contrasts between light and dark.  This generates quite a "loud" signal (lots of firing of neurons) from the get-go.  This is probably a good idea if you want to get people's attention and you are, like the owner in this case, for some reason limiting yourself to doing so by painting an abstract pattern on your house.  (If she really wanted to give her neighbours a hard time, why she didn't paint on an enormous silhouette of a disgusting insect head or something like that, I don't know).  

Stripes

However, contrast is only the start of the story.   Retinal ganglion cells are, recall, not even in your brain, but inside your eyeballs.  From there, the signal is ultimately sent all the way through your brain, to a region, at the back, called the "primary visual cortex", or area "V1". This, together with neighbouring regions (named "V2", "V3", "V4", etc) , is where the brain gets to work processing the picture, identifying features in it, and eventually (it is thought) interpreting what we see.   "V1" is the initial processing unit, and serves as a gateway to the rest of the visual cortex.

It turns out that there is one particular feature that the cells in "V1" get excited by: straight lines.

The scientists who got the Nobel Prize for this discovery were David Hubel (quoted earlier) and Torsten Wiesel.  As they explain, in the following video, they made the break-through more-or-less by accident.  They were showing pictures to a cat and measuring the response of the cells its primary visual cortex, without an awful lot of luck.  One day, they realised that the only thing that was causing a reaction was the edge of the slide as they were inserting it into the projector:

Now, the second clip, below, is really cool.  It shows one of the scientists actually mapping out the position and orientation of the line that each neuron is tuned to, by playing about with the position and direction of the line and literally drawing on rows of crosses over the projected image.  It is awesome to be able "hear" the brain cells responding, as represented by the beeps into which the equipment translates their electrical activity.

There are all sorts of interesting aspects to this research.  For instance, different cells are tuned to different sizes and orientations of line.  Hubel and Wiesel found that the cells in this area of the brain are arranged so that there are little stacks of cells covering all possible orientations within each area of the visual field.

They also found that whereas some cells in V1 only respond to lines in very specific positions and orientations, other cells are more flexible about where the line is placed so long it is in the right orientation.   We apparently don't know for sure how these cells ("complex cells") work, but David Hubel guesses that they must receive their inputs from a bunch of other cells whose receptive fields have the same orientation but are spread out in space.  So long as one of these cells gets excited, the complex cell also gets activated.

The possibility that some line-detecting cells can be wired to receive inputs from other line-detecting cells would logically suggest that you (or, rather, nature) could easily design cells that only get activated if multiple lines of the same orientation are seen.  So whereas complex cells are switched on if this "OR" (in the Boolean-operator sense) another line-detecting cell with the same orientation-preference is activated, these cells would be activated (only) if this "AND" a group of other line-detecting cells with the same orientation-preference were activated. In other words, such cells would be activated by a stripy pattern. And cells like this were, indeed, discovered in the 1990s: so-called "grating" or "periodic-pattern" cells.

The consequence of all this is that stripes are a very elemental features.  They get your visual system excited, because straight-lines (or 'bars', in the parlance of vision scientists) are the very first kind of features that your brain extracts from the image.  There are lots of specific neurons dedicated to doing this job.

A group of parallel lines are even more exciting still to the primary visual cortex because there are other cells dedicated to responding to groups of lines of the same orientation.

And to recall what was said above, the sharp contrast between the red and white stripes adds to the effect, because our retinal ganglion cells (which generate the signal that feeds the brain) respond more to hard contrasts.

So from the perspective of the science of basic visual perception the lady out to get her neighbour's attention totally hit the nail on the head when she decided to paint big red and white stripes on her house.  Stripes are striking.

Social psychology

Of course, just because something is striking does not mean that it is objectionable. 

I actually really like the stripy paint-job on the house in Kensington.  The design is smart, crisp and legible.  The parallel lines, obviously, add up to a pattern.  As well as reflecting each other, they reflect the vertical lines of the edges of the building, and indeed those of adjacent homes.  So whilst the house might be said to be no longer "in keeping" in a first-impression, stylistic sense with its surroundings it certainly makes pattern with them, something which, for my money, is rather more important.

The impression created by a striking pattern of this kind is appealing not just because it is geometrically intelligible, but also because it is suggestive, in an ultimately very comforting way, of the operation, at some stage in the design process, of a human mind - an impression which is tragically lacking in the case of the average Barratt Home with its desultory, random patches of shingling or whatever, and equally in the case of modern blocks of flats with meaningless curves designed into their roofs in a non-committal attempt to inject some 'interest'.

Judging by the reaction of a number of commentators (see for instance this Guardian piece, or this article in Architectural Review), I am not the only one with a sympathetic view of the work.  

So why the hostile reaction from the neighbours and the local authority? 

The reason is surely that painting one's house in red and white vertical stripes is not only striking, but it is very unusual too.  It is not the done thing to paint a house this way.

"We are", Burke observed, "... so wonderfully formed, that, whilst we are creatures vehemently desirous of novelty, we are as strongly attached to habit and custom." As this quote suggests, there is a market in life for both novelty and for familiarity. Equally, we can react badly to both: the novel may make us "uneasy", but the over-familiar, Burke acknowledged, often prompts "... a sort of weariness and disgust".

So far, so ying-and-yang. But things aren't necessarily so equally balanced in the way the manifestation of these responses are distributed over time. We know that our initial reactions to change are usually very negative (status quo bias) . Not only do these change-hating responses naturally fade after time, but, conversely, the creeping horror associated with the mundane takes a while to set in. We might not even notice a building as crushingly banal as the one pictured below when we first move to an area, but walk past it every day for a few years, it can really start to sap, if not your spirits, certainly your reserves of civil pride:

The evil of banality

Not only are our emotional responses over time to the ordinary and to the extraordinary asymmetric, but there appears to be a huge asymmetry in the social acceptability of complaining about these two things.

Whereas an objection to something because it stands out or fails to accord to custom essentially requires no further explanation to be intelligible - it is a recognised, virtually pro forma ground of complaint - an objection to a proposed design based on its blandness can be somewhat harder to articulate. And whereas the objection that "this doesn't fit in" appears to be automatically socially-sanctioned - an impression reinforced by swift response of Kensington & Chelsea Borough Council to the residents' complaints in the case of the stripy house - for some reason people seem to be less sure of their standing to object to something on grounds that it is just too dull. Perhaps this is because status-quo bias of the individual is somehow reflected in the social psychology of complaining. Perhaps it is because people are shy about being assertive before their peers over what are personal, aesthetic preferences: whereas objection to loud stripes can be dressed up as some sort of impersonal concern for the "character" of an area, it is perhaps harder to pretend this is the case when one is criticising a building's banality.

At any rate, this creates a very unfortunate dynamic. It explains why Britain's mass-development suburbs have such a soul-destroying appearance. The public, of course, reflexively blame the developers for that appearance, but this is unfair and rather self-serving. The developers are only responding to the asymmetric incentives that people provide with their own reactions. In a society where people will shrug their shoulders over a mind-numbingly bland design, but will shout very loudly indeed, as they believe to be their socially-sanctioned right, to anything that is the slightest bit unexpected, on which side do you honestly expect the developer to err?

Imagine, indeed, that the exact opposite were the case. Imagine how great this country could start to look again if people had a relaxed tolerance to the building of somewhat garish oddities, but went absolutely fucking ape-shit if anyone proposed to build something that showed a total lack of imagination. For me, that's where the red lines should be drawn.