Wednesday, 4 May 2016

Blindness & Dreaming

Blindness & Dreaming
One of the questions I often see posed on lucid dreaming and dreaming forums is: how do blind people dream? Some people have questioned whether blind people dream at all...

One study which was conducted at the University of Hartford (1999) undertook an analysis of 15 blind people and 372 recorded dreams from this sample. The results showed that those people with congenital blindness, or who lost their sight before the age of 5 years, did not experience visual dreams. This is because our dreams are largely made up of waking life experiences (as well as our desires, wishes, fears and anxieties), and therefore, those who have no experience (or memory) or visual or light perception will not manifest visual imagery in their dreams. 

Many people who become blind in later life tend to report that the faces of familiar people (who they saw when their sight was intact) become gradually more blurry in dreams over time and do not 'age' in the dreamworld - they appear exactly the same as they were at the time the blind dreamer was able to see them in waking life.

People who lost their sight later in life report that they experience visual dreams for longer periods, post-blindness. Of the subjects who lost their sight between the ages of 5 - 7 years, some reported visual dreams and other did not. However, there seems to be no link between the intensity, richness and imaginativeness of dreams and visual content. 

It is assumed that blind people experience some form of sensory compensation; like those of sighted people, dreams are composed of, and representative of, their real-life experiences and sensory perception, meaning dream content is likely to involve sound, smell, taste and touch. 

According to a study published by researchers from the University of Copenhagen and Glostrup Hospital in Denmark in Sleep Medicine (2014) supports this theory, claiming that the dreams of blind people contain the sensory perceptions which they use to navigate their waking lives. Among congenitally blind volunteers, 93% heard, 26% tasted and 40% smelled in at least one dream. The study involved 50 adult volunteers; 11 who were blind from birth (or congenitally blind), 14 who became blind after age 1, and 25 sighted controls. The study lasted 4 weeks, during which dreams were recorded and sensory perceptions/emotional themes analysed. As expected, all the sighted subjects reported seeing visual imagery in at least one dream, while none of the congenitally blind subjects reported any. Amongst those who lost their sight after age 1, the subjects who lived with blindness the longest reported the fewest visual impressions in their dreams. 

Blind participants experienced other senses more intensely than subjects in the sighted control group. About 86% of blind subjects reported hearing in at least one dream, but only 64% of the control group subjects did. About 18% of the blind subjects tasted versus 7% of controls and 28% of the blind subjects smelled in at least one dream, compared with 15% of the control group subjects. A huge 70% of the blind subjects reported that they experienced touch in their dreams, in comparison to 45% of the control group subjects. Distinguishing between congenitally blind subjects, 93% heard, 26% tasted and 40% smelled in at least one dream, while 67% experienced touch. Blind subjects’ dreams were just as bizarre as those of their sighted counterparts. Both groups’ dreams also featured similar amounts of successes, failures and social interactions, and the same frequency and intensity of each emotion.

Studies have also shown that blind people seem to experience more nightmares that people with sight. In the 2014 study, it was found that About 25% of congenitally blind participants reported that at least one of their dreams was a nightmare, versus 7% of the later-onset blind group and 6% of the sighted control group subjects. This may be due to the evolutionary theory of dreaming, which suggests that our dreams and nightmares are 'threat simulations' - mental rehearsals for potentially distressing life events, which prepare us and help us develop or practice coping or survival mechanisms. Common themes of nightmares experienced by blind people tend to involve getting lost, being hit by a car or losing their guide/seeing eye dog. 

Similar trends in a study published in Neural Plasticity (2015), in which 14 congenitally blind and 14 sighted individuals sniffed sweat samples from volunteers who had watched film clips which evoked emotions of amusement, fear, disgust or sexual arousal. Congenitally blind subjects did better than control group subjects at identifying fear and disgust. Ron Kupers, a faculty member at the University of Copenhagen’s Department of Neuroscience and Pharmacology, who led both the Sleep Medicine and Neural Plasticity studies, explains: 'If you don’t have any visual input, you have to get information from other sources'.

Kupers is currently investigating which aspects of visual memory – the ability to visualize colour or faces, for example – fade first in individuals who suffer from late-onset blindness. Another ongoing study will compare the sleep patterns of sighted and congenitally blind subjects, some who have had their eyes removed. Kupers expects blind individuals (who lack so-called non-image forming retinal ganglion cells which are crucial to controlling sleep-wake patterns), to experience sleep disturbances, which are  also linked to a myriad of health problems, from obesity to Alzheimer’s disease. As the population steadily grows older and our life expectancy increases, these findings could also apply to people suffering from age-related eye diseases, like macular degeneration. 

Further research into blind people (who do not experience visual dreams) found that subjects do not tend to experience REM (rapid eye movement) sleep, even though they were capable of having vivid sensory dreams. This highlights one of the assumed functions of REM - our eyes may be moving during our dreams because we are scanning the visual environment of our dream world, much in the same way we use our eyes in our waking life. If blind people do not experience REM during dreaming because they are not experiencing a visual dreamworld or visual dream imagery, it seems likely that there is little other purpose for this phenomenon.

I have never asked - or heard reliable anecdotal evidence - from a blind person as to whether it is possible for blind people to lucid dream, but there is no reason why this is not just as possible for blind people as it is for those with sight. The method by which a blind person becomes lucid may differ: for me, I tend to recognise dreamsigns in a non-lucid dream, which triggers a mental or physical reality check and conscious awareness that this is a dream (lucidity via a DILD - Dream-Initiated Lucid Dream). Perhaps blind people are able to recognize non-visual sensory dreamsigns? This would be an extremely interesting topic for an empirical study.

Dream Under a Desert Sky  by Stella De Genova 
(Visually Impaired Artist)

Colourblindness & Dreaming
Studies into colourblind people also reveals the extent to which our dream perception is reflective of our waking experiences. It is predicted that around 8% of males and 0.5% of females with Northern-European heritage suffer from red-green colourblindness and research shows that this visual defect is also present in their dreams. Red-green colourblindness is the most common form of this defect, and accounts for around 99% of those diagnosed with colour-blindness or colour vision deficiency disorders. If a colourblind person loses their colour perception in later life, it seems that their dreams will have normal colour perception - as long as they have sufficient long-term memory of these colours.

People suffering from complete achromatopsia (total colour vision deficiency) since birth, only perceive visual imagery in shades of grey or monochrome (black and white). This is a very rare disorder which is thought to affect approximately 1 on 30,000 people worldwide. Persons with achromatopsia would not dream in colour as they have no perception of what colours look like, and no memories from which to fabricate colours in the dreamworld.

There has also been research into why some people report only (or mainly) dreaming in black and white. In the 1950s, dram researchers assumed that everyone typically dreamed in black and white, and to some extent, this idea has prevailed, with many people questioning if we do indeed dream in colour, or simply perceive our dreams in monochrome and then attribute colours to the memory of the dream upon waking. This theory was put to rest by study by Eric Schwitzgebel, a philosophy professor at the University of California at Riverside. The study published in Studies in History & Philosophy of Science (2000) and suggested that the prevalence of black and white dreams which were observed during the 1950s were likely to be the product of technological advancements during this era - movies and TV were of increasing significance in people's waking lives, and these were displayed in black and white.

One study at the University of Dundee (2008) was able to replicate these findings, claiming that people from the generations who grew up watching black and white TV tended to dream in black and white, despite experiencing the full colour spectrum in their everyday waking lives. Those who grew up post-1960s, when colour TV was more widespread, report dreaming in full colour. 

Deirdre Barrett, a psychologist at Harvard Medical School, states that nowadays it is not common for dreamers to report black and white dreams, unless they are heavily exposed to black and white movies or TV.

Sometimes we can't recall colours in dreams. This does not mean that we experienced a black and white dream, simply the colour element of the dream was not vivid or memorable enough to imprint on our memory. The more effective your dream recall is, the more likely you are to remember your experience of colour in a dream. Barrett notes that if you can't remember the colours of your dreams, it may be because you simply don't focus on them or pay attention to them -  this selective perception of sorts is similar to how different people perceive the real world.  Barrett states: 'If I asked you to describe something that happened 2 days ago, you might include no colour in the incident - or you might...If I asked you what colour someone was wearing, you might be able to tell me or not - color just isn't always a salient part of events. The events may be more about the interpersonal aspect, such as navigating or trying to get somewhere, while at other times, colour is significant to whatever we're doing and noticing'.

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