Baby got black (and white…)

I have a brand new niece. Two, actually – although the other one has a full year’s life experience over the freshest one. Not having ever ‘known’ any other babies before, my two nieces have provided an amusing (and responsibility-free!) experience in human development and learning.  As I specialise in the degeneration of the brain and when it goes wrong, it’s been pretty fun and interesting to see those two little girls develop and begin to understand the world.

So I thought I’d write a post about one of the things I’ve recently learned about baby development – they LOVE looking at black and white things. This is apparently a very well-known fact to new parents, but why do babies like looking at black and white things so much, and how does it affect their brain?

I didn’t know, so I have tried to find out!

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A LOT is known about vision and the development of the visual system (by other people, not by me), so I have tried to really trim it down to specifically answer just the black and white question…

First things first…

At the back of your eye is your retina, which is the area that detects light and conveys information about that light down the optic nerve, which connects your eyes to your brain. The information then travels to the visual cortex – the region of your brain at the back of your head. It is here that we make sense of what the light entering our eyes means, and turns that information into what we perceive, or ‘see.’ This is our visual system.

We require visual input (i.e we need light and to be able to see things) for our brains to develop the ability to discriminate between objects and to tell the difference between colours and shapes. In the womb, there is no such input, so at birth the visual system is not yet fully developed.

It makes sense to assume that as a baby’s brain is less developed than an adult’s, then it would have less brain cells with fewer connections between them. However, this is not the case. In the visual system, babies have an excess of brain cells with many more connections. This is because during development in the womb, brain cells in the visual system will randomly fire (send signals) all over the place – this allows the brain cells to start growing, and prepares the visual system for that magical day when it gets to experience light.

However, there is not yet any structure or order to the system, and there would be a lot of meaningless communication (or noise) between cells, so it isn’t very efficient. The experience of light and vision in the first few months after birth are crucial for the strengthening of particular connections in the visual system and for the formation of a proper, organised structure. The connections and cells that are not used are lost (or pruned).

The development of the visual system in these first few months and years is known as the ‘critical period’ – this was described by Nobel Prize winners Hubel and Wiesel in the 1960’s. During this period, if there is no visual experience, the visual system will not develop properly, and normal sight will never be achieved.  

So babies don’t have a well-developed visual system, and they require visual experiences to fine-tune their vision for normal sight.

But why do they prefer black and white?

Well, it seems that babies pay more attention to things that cause greater brain activation than things that cause less brain activation.

I mentioned the organisation and structure of the visual system before – different brain cells respond best to different visual stimuli, and brain cells that respond to similar things tend to group together. For example, some brain cells will have their strongest response when a vertical line is seen. The response of the cell will decrease as the line moves away from vertical, and will not respond at all to a horizontal line. However, another cell will prefer horizontal lines and will respond best to these. As clear, well defined vertical and horizontal lines elicit the strongest cellular reactions, these are initially given the most attention.

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Similar preferences exist for colour saturation, hue and contrast. Black and white patterns have the greatest level of contrast, so will cause the largest response in the visual system – as lines become blurred together to form grey, there would be reduced contrast, which causes less of a response, so it is harder to discriminate and is therefore less interesting! The experience of seeing sharp lines and edges helps to shape the visual system and form important connections that will form the basis for understanding more complex shapes.

On top of this, the retina is still developing up until 3-4 months of age, and the cells that detect colour mature slower than those that detect light intensity or brightness. This means that babies are less able to tell the difference between different colours in the first few months of life. That means that a pattern of red and green is much less interesting than a pattern of black and white, which looks more like the presence and absence of light.

So that was a whistle-stop tour of my basic understanding of the development of the visual system!

My niece likes to look at black and white pictures because that’s what her visual system responds to best, and this kind of stimulation is helping to form strong, meaningful connections between her brain cells that lead to the development of her visual system.

If you have any questions, feel free to ask – but it will take me a while to respond as I’d have to look it up!

Also feel free to ask me about any neuroscience or biochemistry topic you are interested in or want to understand more about, and I’ll try to respond with a post about it!

 

The Biocheminist

 

 

References:

http://www.nainr.com/article/S1527-3369(08)00135-9/abstract

http://psycnet.apa.org/psycinfo/1979-23234-001

http://www.mitpressjournals.org/doi/abs/10.1162/jocn.1990.2.2.81?journalCode=jocn#.VATJbvldVNs

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