Category: Crossmodal brain plasticity

Sensory adaptation

smackenz/ / Crossmodal brain plasticity, Crossmodal correspondences, Haptic touch, Movement, Multisensory, Posts, Proprioception, Vestibular

When sighted people ask about being blind, they often wonder:

Is it like seeing black all the time?

My favourite conversation about this took place on the metro in Oslo. I was doing research on blindness. And the person who asked seemed to be sleeping rough. I answered, ‘No, because there is nothing there to see black with’. She lifted her index finger into the air and cut straight to the chase: ‘So, like seeing with my index finger. Or my big toe.’

Is it better to have had vision or to be born blind?

But people seem to know, intuitively, that there is no single answer to this. My response is usually: ‘It depends.’ Then people, often spontaneously, talk about recognising friends by their faces; yet they soon realise that voices are just as important – as are the skills needed to identify them. Some also talk about the smell of colours, mostly ocean blue and grass green. (See our blog for the scientific approach, the crossmodal correspondences between the senses, Crossmodal brain plasticity and empowering of sensory abilities, and Multisensory processing.)

How long does it take to adapt to being blind?

Again, my answer usually is: ‘It depends’ – on when and how vision was lost, the use of other senses before and after, and overall health. The brain must adapt to recognise sensory information without vision. And new habits take on average 66 days to become automatic. (See our blog for Decay and maintenance of sensory memories, Visual memories and sensory experiences, Reading braille in colour, and My vision, my identity.) I wonder, therefore, if it would be better to ask not how long it takes to adapt, but rather: how to adapt?

In an attempt to explore this question – how do people adapt to new sensory information? – I started brushing my teeth with my left hand instead of my right. Doing this meant adapting to new sensory information, especially from proprioception, touch, and the vestibular sense (see our blog for Growing into one’s own body). Drawing on previous research on people who have lost vision, including some of my own work, I expected to:

– Do well on my first attempt, then struggle to adapt to sensory information from my left hand

– Have slip-ups – old habits die hard – that would set me back in my progress

– Try different routines before fully adapting to sensory information from my left hand

My first attempt went well, but then came the second and the third – and they felt strange. Holding the brush was awkward, and I did not really know how to move it properly. It felt as if the brush was sliding around with no clear purpose. And I was certainly not convinced my teeth were clean afterwards, but I resisted the temptation to go back to using my right hand.

Then, attempt five – and my first slip-up. I suddenly realised that my movements with the brush were different, and next came the feel of it against my gums. Judging from the position of the brush this was my usual right-hand brushing routine, I had at least caught my slip-up early.

For the next attempt, I reminded myself – even said it out loud – to use my left hand. I was expecting this brushing to be more difficult, but I did not notice any real setback. And I wondered if this was because I had not yet formed a routine for brushing with my left hand.

young child smiling and brushing teeth
AI-generated illustration for SmartSense

To stay on track, I decided to pay close attention to what I was doing from the moment I applied toothpaste to the brush. I noticed the difference in how I used my two hands. With my right hand, I used a full-hand grip to hold the brush. My wrist was often stiff, and the pressure on my gums was quite hard. With my left hand, I flexed the brush in my grip: I held it almost as if I were holding a pen, sometimes adding my middle finger; I gripped it between my index finger and thumb, again sometimes bringing in the middle finger, and my wrist bent, stretched, and turned. The pressure on my gums was much lighter than with my right hand.

Over the next three to four weeks, I began to establish a routine for how I brushed – moving from the left upper teeth, across to the right, then down to the right lower teeth, and over to the left, before returning to the middle for an extra clean. My grip on the brush became firmer, and the pressure on my gums more constant. It no longer felt as if the brush was sliding around with no clear purpose. And I was almost convinced my teeth were clean afterwards. I had had three slip-ups, but I caught them early and carried on brushing with my left hand. It was time to try a deliberate right-hand brushing again.

Week seven, day one: return to right-hand brushing. At this point, I had a consistent routine for my left-hand brushing: the movement and feel of the brush were the same every time. Returning to my right hand was a bit of a shock. My right hand now felt inferior to my left: the handling of the brush was less flexible, the pressure on my gums was harder, and my teeth did not feel any cleaner than with my left-hand brushing. Next time, I brushed with my left hand again, without noticing any setbacks in my progress. In fact, left-hand brushing now felt more natural to me.

I have continued with my left-hand brushing, and if you asked me which hand I used this morning, I would not be able to tell you. But it was most likely my left.

My required adaptation was both minimal and reversible – only two to three minutes in the morning and evening, and it could be stopped at any time – and so should by no means be taken as representative of how people adapt when every aspect of their life has to change. For example, after total sight loss. There is also a little twist to my experience. I am “a leftie” who was trained to use my right hand. So, I wonder if my adaptation to new sensory information was facilitated by some pre-existing left-hand architecture in my brain. Still, I hope my experience offers a glimpse into how people adapt to new sensory information.

See our blog for Activities; especially 94-96.

Blog post author: Dr Torø Graven

Reading braille in colour

tgraven/ / Colour, Crossmodal brain plasticity, Crossmodal correspondences, Haptic touch, Multisensory, Vision

Previous research has found that people who have just started reading braille by haptic touch try to imagine the characters visually. For example, seeing black spots on a white background and associating the formation of these with regular print characters, objects they have seen, or both. When they become tactually more experienced, this stops. In contrast, people who are born blind recognise the braille characters through either their quantity and location of dots or their tactile global shape1. (See our blog for the scientific approach, Vision, haptic touch, and hearing, and Decay and maintenance of sensory memories.)

This time, I wanted to explore what happens when people stop trying to imagine the braille characters visually. To shed some light on this, I have invited I.A. to share her experiences. Born partially sighted, with about 5% vision in one eye, I.A. started reading and writing regular print. I.A. learned braille on her own at around 13 years old: first memorising the braille alphabet, using a combination of vision and haptic touch. Then reading materials published in both regular print and braille. About three years later, I.A. was no longer able to read regular print. She now knew all the braille characters by haptic touch, but needed help to perfect her reading technique. Today, I.A. has been reading and writing braille by haptic touch alone for more than 25 years. She has been teaching braille to people who have become blind for more than 10 years. And she is an appointed Board Member of the braille authority in her country. I.A. approved this text before we posted it on our blog. The journey she is taking us on is rather unexpected.

For the first two or three years of reading braille by haptic touch alone, I.A. saw the dots in each character as mini light bulbs in her mind’s eye. She concentrated on how many they were and where they were located.

Gradually, I.A. started perceiving the tactile global shape of short two and three letter words. For example, of ⠉⠁⠞ (cat) and ⠙⠕⠛ (dog). She still reads longer words letter by letter, but she has stopped seeing their dots as mini light bulbs in her mind’s eye.

Reading by haptic touch alone, I.A. recognises the braille characters through their quantity and location of dots. She recognises short two and three letter words by their tactile global shape.

As I.A. became more experienced in reading braille by haptic touch alone, the letters started appearing in colour – just as they had done in regular print. For example, a in red; b in dark blue, c in light yellow, d in dark yellow, e in pale blue; f in blue-grey; g in green; h in beige; i in translucent white, j in white, and so on.

And the numbers too: 1 in white; 2 in yellow; 3 in blue, 4 in light yellow; 5 in green; 6 in blue, 7 in white, 8 in red, 9 in brown, and 0 in silver grey. Some punctuations and signs also have the same colour as in regular print; like “division” (÷) which is yellow, while others gained a colour in braille, like “equals” (=) which is now mossy green.

I.A. experiences synaesthesia. She associates certain letters, numbers, punctuations, and signs with certain colours (see our blog for the crossmodal correspondences between the senses and the intriguing association between sounds and colours).

I.A.’s synaesthesia appears only when reading. She does not associate letters, numbers, punctuations, and signs with colour when writing. But, as soon as she checks her spelling, they appear in colour again.

When reading shorter words, like “cat” and “dog”, I.A. first detects the tactile global shape of the word and then associates it with colour. That is, the colour when combining all the letters. The word “dog” for example is a combination of (d) dark yellow, (o) silver grey, and (g) green. I.A. sees “dog” as a mossy green word.

According to I.A. the colour helps her distinguish between words with a similar tactile global shape. For example, ⠙⠕⠛ (dog) and ⠋⠕⠛ (fog). While “dog” has a mossy green colour, “fog” is light green; that is, a combination of (f) blue-grey, (o) silver grey, and (g) green.

Longer words, that I.A. reads letter by letter, are coloured by their first letter. For example, the word “braille” is dark blue and “crossmodal” is light yellow.

It seems I.A.’s subjective crossmodal correspondences are not sensory specific: they exist regardless of whether she is reading regular print or braille. Could they be linked to information that transfers between vision and touch? For example, shape. Or, are they rather linked to the sound of the letters, numbers, punctuations, and signs (see our blog for the scientific approach, the crossmodal correspondences between the senses and the intriguing association between sounds and colours)?

See our blog for Activities; especially 58-60.

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1Graven, T. (2015). How blind individuals discriminate braille characters: An identification and comparison of three discrimination strategies. British Journal of Visual Impairment, 33(2), 80-95.