Monthly Archives: May 2016

Identifying cognitive phenotypes for the reading deficits in dyslexia

This post has been contributed by Max Coltheart

I am not starting at the behavioural level to define the reading deficits in dyslexia. I would get lost in a maze where cause and effect can hardly be distinguished.

Behaviour is determined by so many factors that a glitch in just one of these factors is incredibly hard to discover. It’s like being in the midst of climate change and generally rising temperatures, while being confounded by a cool summer. Like the observed cool temperatures, observed behaviour is potentially misleading if we want to learn something about what causes the behaviour.

Therefore I am starting at the cognitive level. I will only later go to the behavioural level when I know what signs to look out for. At the cognitive level I can let my thoughts range freely around the imagined mental machinery. I would like to poke into different bits and take them apart. I would like to see what would happen if a particular piece were missing or not working properly. Would the projected outcome resemble the real reading problems that are experienced by dyslexic people? Continue reading Identifying cognitive phenotypes for the reading deficits in dyslexia

What parts? What mental machinery? Well, it is just a metaphor, and it may be better to talk of apps, perhaps. But here are some ideas. I believe learning to read involves acquiring a number of gadgets and these enable us to become the skilled readers that many adults are. When any of them goes wrong, reading deficits should result (acquired dyslexia). When any of them are never acquired properly, reading deficits should also result (developmental dyslexia).

If we can find clues to the gadgets and what can go wrong, we are on the way to understanding what the gadgets that make up the reading system are. Progress! But how many are there? Can they each go wrong, separately or together? Here I am speculating and limit myself to 7 hypothetical mechanisms.F1.large (1)

Perhaps any of the 7 mechanisms can be broken in dyslexia. This leads to different forms of dyslexias and hence different cognitive phenotypes and explains the heterogeneity of the dyslexia condition. It can also explain different degrees of severity – the more the worse, obviously. Testing different mechanisms separately has led us to form subtypes of the dyslexia condition.

How then do you identify cognitive phenotypes?  You need to devise behavioural tests to capture the hypothesised cognitive deficit. We have tests for identifying how well each of the seven components in the Figure are working.

It has been beautiful to discover reading specific architecture, a whole city of familiar, yet different, patterns of impairments and preservations of the components of this architecture.

Time we identified cognitive phenotypes for the social deficits in autism

Social deficits? Their not the same as everyday difficulties in social situations. We all have experienced such difficulties, because the social world has as much potential for suffering as for happiness. But when we talk of social deficits in autism it’s about not being quite part of the social world. Yet, it’s not about deliberately withdrawing from this world and not about being antisocial.

I am not starting at the behavioural level to define the social deficits in autism. I would get lost in a maze where cause and effect can hardly be distinguished. For instance, there are people who often feel rejected, while others find them unbearably aggressive. Which comes first, the rejection or the aggression?

sociability_tup_wanders_flickr

Continue reading Time we identified cognitive phenotypes for the social deficits in autism

Behaviour is determined by so many factors that a glitch in just one of these factors is incredibly hard to discover. It’s like being in the midst of climate change and generally rising temperatures, while being confounded by a cool summer. Like the observed cool temperatures, observed behaviour is potentially misleading if we want to learn something about what causes the behaviour.

Therefore I am starting at the cognitive level. I will only later go to the behavioural level when I know what signs to look out for. At the cognitive level I can let my thoughts range freely around the imagined mental machinery. I would like to poke into different bits and take them apart. I would like to see what would happen if a particular piece were missing or not working properly. Would the projected outcome resemble the real social problems that are experienced by autistic people?

What parts? What mental machinery? Well, its just a metaphor, and it may be better to talk of apps, perhaps. But here are some ideas. I believe evolution has endowed us from birth with a number of gadgets and these enable us to become the social creatures that we are. When any of them goes wrong, social deficits should result, – not to be confused with everyday social difficulties.

If we can find clues to the gadgets and what can go wrong, we are on the way to discover their neural basis and eventually their genetic origin. Progress! But how many are there? Can they each go wrong, separately or together? Here I am speculating and limit myself to 7 hypothetical mechanisms. Lets call them start-up kits, since they are subject to learning and development.

SupK3

Start-up kits for a thoroughly social human being

  • Agency recognition (prey, predator, mate, friend, enemy
  • Affiliation (recognising kin, bonding, attachment)
  • Alignment (mimicry, resonance, contagion)
  • Belonging (identity, trust, loyalty, ingroup/outgroup distinction)
  • Hierarchy (knowing one’s place, dominance/submission, alliances)
  • Mentalising (mental state tracking, persuasion, deception, reputation)
  • Morality (fairness, equity, altruism, punishment)

I imagine these start-up kits run on the fuel of social emotions to regulate social behaviour (think guilt, shame, jealousy, pride, contempt). They depend on other social signals too, as displayed in eye gaze, voice and body language. For my money, its the last two, mentalising and morality, that have some claim for being uniquely human and being shaped by cultural learning. They also have some claim  for being broken in autism.

Perhaps any of the 7 mechanisms can be broken in autism. Perhaps this leads to different forms of social deficits and hence different cognitive phenotypes. This would go some way to explain the heterogeneity of the autism spectrum. It might also explain different degrees of severity – the more the worse, obviously. Perhaps testing different mechanisms separately would lead us to form subgroups in the autism spectrum. As far as I know this has not been done in any systematic way.

If they’re not broken, these hypothetical mechanisms work spontaneously and effortlessly, and are active throughout an individual’s life. This is reminiscent of instincts. They respond to a certain set of stimuli with a certain set of flexible responses. However, the responses can be suppressed or modified via conscious control.

To what extent these mechanisms are independent , or interacting with each other, is a matter for debate. If they were separate then, when one of them wasn’t working, a ‘hole’ in the mental architecture would appear, but the rest might function well. Do holes matter? It depends. Compensatory learning is a wonderful thing. If it works then the hole can be covered up to make it almost invisible in behaviour.

How then do you identify cognitive phenotypes?  You need to devise behavioural tests to capture the hypothesised cognitive deficit. Sadly, we don’t have the tests. This is not because they are impossible to design, but because nobody has made the necessary major effort to devise a systematic battery of tests that are reliable and sensitive.

Most of the tests we have so far give you a score that estimates a level of performance, but they don’t tell how that score was achieved. We need tests that can do precisely that. Moreover, we need to be able to detect how a score was achieved. It could be low, because of fatigue. It could be high, because of compensatory training. So, constructing valid and reliable tests is not a trivial task, they need a lot of man power and, of course, funding.  I expect this is why we haven’t got them yet..

All the experimental tests we have at present are precarious. This is why I am not impressed when somebody tells me that, on tests in the lab, their autistic child is no different from any typically developing child, and hence there is no difference in underlying mental architecture. I think it would be beautiful to discover autism specific architecture, a whole city of familiar, yet different, structures.Urville18

 

Image credits:

Tup Wanders Flickr creative commons http://bit.ly/25k4odQ                                                          Chris Frith                                                                                                                                                            Gilles Trehin, Urville http://bit.ly/1XzJu84

 

 

This cognitive thing

Five years ago I wrote an opinion piece for the SPECTRUM (then SFARI) Autism website. I doubt that the message I wanted to get across  – did.

So I am trying again.Framework5With this simple framework I think we can declutter our thoughts about autism.

Continue reading This cognitive thing

What’s the problem with our current thinking about autism? If you have a Post-it note handy, we can start by drawing some lines to create spaces for what we already know and what we don’t. Framework1

We’ll reserve the top space for facts about the remote biological causes of autism. You could list an impressive number of risk factors here, such as susceptibility genes, and differences at the cellular level and differences in the size, activation and connectivity of brain structures, for example.Framework2

The space at the bottom is for all the behavioural observations,and performance on neuropsychological or psychometric tests. Behaviours reported by parents, behaviour assessed by questionnaires or interviews would be listed here as well. There is a huge amount of data: for recognition of faces alone, there are hundreds of papers.Framework3

The middle space between the two lines is the interesting one. It’s the ‘cognitive thing’.  This is for ideas about what is different about the mind of someone with autism — and the core of my obsession. Framework4

Here’s a hard question: How does an individual find meaning in the world and act on the world? Answer: Through cognitive mechanisms that allow the individual to learn and to adapt in its environment. These mechanisms have a basis in the brain and have been honed by evolution over millions of years. For the individual they come for free as  as start-up kits and they are active right from birth.

By the way, in this framework the term ‘cognitive’ describes everything that the mind does, consciously and unconsciously. It does not just refer to perception, attention, memory, reasoning. It refers to all aspects of mental life.  And this certainly includes emotion, motivation, reward learning.

The cognitive level is also the space for imagination and controversy. Here we can’t observe and measure facts; we can only propose hypotheses. Of course they have to be amenable to being tested both on the biological and the behavioural level. It seems to me that in our state of ignorance, we might as well be bold. I have already inserted two of my favourite hypotheses to explain what is different about the autistic mind, mentalising and detail focus.  I hope you will put forward your own hypotheses.

The  mentalising hypothesis is very bold. It proposes that  we are all born with a social GPS. The GPS tracks what others think and feel from moment to moment. This allows us to orient ourselves in social space without having to consciously think about it. Autism means not having this GPS, but instead having to rely on a map. This works, but is slower and more effortful. There are many tell-tale signs in behaviour and in the brain that seem to support this hypothesis.

Autism isn’t just about social communication. It is also about having a way of thinking, which can be described as ‘detail focussed’. The idea is that autism involves sticky attention to small parts at the expense of attention to the bigger picture. Thus local sensations can become overwhelming. This can be rephrased as giving less weight to prior expectations that prepare you to perceive a particular thing, and instead giving more weight to incoming information, both signal and noise. 

We need such bold hypotheses. Here’s why: Behavioural and biological data only become meaningful if they can be explained in terms of what the mind does. Understanding that a child lacks a social GPS is far more helpful to a teacher than knowing that he or she has a particular genetic abnormality (biological); or tends not to look at eyes (behavioural). Likewise a teacher can understand that a child who is overwhelmed by bitty information may be terrified by the smallest changes in his or her environment. 

We now have a structure that we can use to lay out what we have already learned about autism. I have drawn lines on Post-it notes, but if you want to insert all the facts that are already known, you will need a very large sheet of paper!

We can also use this simple layout to imagine how our knowledge might expand in the future. I have written about this with John Morton in 1995, and most recently in 2012.

The holy grail of autism research is to identify the commonalities of the autism spectrum. These commonalities should lead to defining cognitive phenotypes. Then it will be possible to trace causes of autism from genes to behaviour.

We know a lot already, but how can we pull the existing findings together? We need to find a common pathway — the critical part in the system that is always affected, no matter which of the numerous genetic and environmental risk factors have placed an individual  on the autistic spectrum.

Framework6

If we were to find a common pathway, this would define a distinctive property of the brain that is critically different in autism. The common pathway forms a node in a network of possible mappings: It pulls together all the strings from the data that are already available and from the data that are not yet available, but can be predicted.

If we can find a node at the cognitive level, animal models become more informative, for example. This is because one can look beyond behaviour, which is obviously very different in mouse and man.

To me there is something very appealing about pulling together the strings in a common pathway. No wonder I’m obsessed with this cognitive thing.

There is a thorny point here: The node would pinpoint both normal and abnormal function. But isn’t this too black and white? Isn’t everyone ‘a bit autistic?’

I happily agree with this at the behavioural level, where one thing always shades into another. A measure of amount of eye contact, for example, will vary continuously across different individuals — we can only make an artificial cut-off point to define what is ‘abnormal.’ The same goes for the biological level: If you assess neuro-chemical levels, you will get a continuous distribution, with clinical groups tending to lie at one extreme.

At the cognitive level, however, it is admissible to use categorical distinctions. We are free to theorise that there are functions that the typically developing mind automatically performs, which the mind of a person with autism performs in a qualitatively different way, or not at all — and vice versa.

So here’s my message: We shouldn’t despair of ever finding clarity in the ever more complex world of possible biological causes and dimensionally varying behaviours. If we focus on the mind, we can make sense of the enormous complexity by testing daring hypotheses that can pull the strings together.

The Encounter

Over the last couple of years, Uta & I have been meeting with Simon McBurney, director of Complicite as he prepared for his one-man show, The Encounter. Simon hoped that we might be able to tell him what neuroscience can reveal about the nature of consciousness.

The Encounter dramatizes the experiences of Loren McIntyre, as described in Amazon Beaming by Petru Popescu. When Simon told us about this book it was long out of print, but we managed to find a second hand copy. As a result of Simon’s work it was republished in 2015.

Loren McIntyre was a National Geographic photographer, and this is the story about his experiences when he was lost in the remote Amazon rain forest. His survival depends on the leader of a small group of Mayoruna people who he has followed into the jungle and then become hopelessly lost. But there is no common language through which they can communicate. He feels utterly isolated with ‘a psychological distance of 20,000 years’ between him and the people who are his only hope finding a way back. Eventually he starts to experience ‘communication’ from the leader of the group when he sits near him. He begins to understand some puzzling behaviour, for example, why the group keep destroying their villages and moving on. Remarkably, this communication doesn’t depend on language.

McBurneyIn The Encounter everyone in the audience wears earphones, which helps Simon to recreate and share all the strangeness and terror of McIntyre’s experiences through the wonder of acoustic technology.

When we first talked to Simon about the work he was developing around Amazon Beaming, he asked us whether we thought it was possible for two people to communicate without words. We said, absolutely.

And here is why.

Continue reading The Encounter

Communication is not simply about the transfer of information. You can do that with a cash machine. When we communicate we know that we are communicating, and we know that our partner knows that she is communicating. We have a subjective, conscious experience of communicating. This experience, we hypothesise, predates language.

This is what I would have said in a discussion planned after a performance of The Encounter at the Barbican. Unfortunately I couldn’t be there because I had to have an operation for a detached retina.

What is conscious experience?

When I look out into the audience, I am aware of innumerable faces. I have the subjective experience of seeing many faces. But this is an illusion. I don’t mean that you are all figments of my imagination. I am confident you are all out there, but, even so, some of you at least are figments of my imagination.

The problem is that my contact with you all seems so direct, when it is really very slight. The only clues I have about you come from the sparse signals that my eyes and ears are sending to my brain. From these crude signals, and from years of experience, my brain can make quite a good model of what’s out there.

elephantYou will remember the story of the blind men who come across an elephant. One feels its trunk and thinks it is a snake, another feels its leg and thinks it is a tree.

A single sighted man who comes across an elephant is doing the same thing. The elephant is too big to see with a single fixation of the eye. We have to look all over it. If our eye lands on the trunk, then it’s a good bet that it’s a snake. But, then, as the eye moves along it a head or a tail should appear. When this doesn’t happen, then the model has to be changed. It isn’t a snake. Perhaps it’s an elephant. The more evidence our eyes take in the more plausible it becomes that the thing is an elephant. Our eyes move very fast (4 to 8 fixations per second). Within a few 100 msecs we see the elephant. We are entirely unaware of all the work our brain has done and, of course, what we are seeing is not the elephant, but the model that our brain has constructed. This model is often incomplete with several missing bits that are filled in with guesses. This is why some of you are figments of my imagination. There is a well known youtube video, showing that a gorilla can walk by some basketball players without being noticed, if you are too busy counting the basketball passes.

But what is the point of all this vivid subjective experience?

HuxleyCapTH Huxley believed that our conscious experience has no function: ’Consciousness [is]completely without any power of modifying the working [of the body] as the steam-whistle which accompanies the work of a locomotive engine is without influence upon its machinery.’ I believe that Huxley was wrong and we can see this from the metaphor he chose. This is because the steam-whistle does influence the behaviour of other engines.

Our conscious experience is very vivid, but also very private. There is no way I can have your experiences. It even is possible that the colour experience that I call red is actually the one you would call green if you were to experience it. How could we ever know? But there is a paradox here. Our conscious experience may be private, but it is also the only aspect of our mental life that we can share with others. I can’t tell you anything about what my brain is doing. And I certainly can’t tell you about all those mental processes that never reach my consciousness.

enginesCap

 

What I can tell you about is my model of the world. And, at the same time, you can be telling me about your model of the world. So if we are like steam locomotives, we are certainly hearing each other’s whistles.

 

 

 

Conscious experience is for interacting

And, because we are sharing the same world and because we also have very similar brains, our models are also likely to be very similar. But they will not be entirely similar. Our models will also depend on all our past experiences including our interactions with others. Our models of the world will be strongly influenced by our cultural background.

But what happens when two people interact? Interacting with another person is different from interacting with a rock. Unlike a rock, the person I am interacting with is creating a model of me at the same time as I am making a model of her. The model I create of you helps me to predict what you are going to do, which also helps me to communicate with you. My model of you will have many different aspects. I will try to discover what sort of person you are. But in my view the most important aspect of you that I am trying to model, is your model of the world. That is the model of the world we are currently sharing.

brainsBecause we are sharing the same world, any differences in our models will reflect our different experiences and cultural backgrounds. So, when I know something about your model, I know something about you. But, if I need to communicate with you, then I should try to make my model similar to yours. And, at the same time, you will be trying to make your model similar to mine. Some believe that, if two devices interact while making inferences about each other, then they will eventually converge on the same model.

Language is extremely useful for discovering something about other peoples’ models of the world, but it is not the only way. Simply by watching how someone moves you can learn about how they see and understand the world about them. The more you spend time with someone else, the better you will get at predicting how they are going to move. You won’t know how you do it. It just happens.

To make this prediction you have learned about their model of the world and, inevitably, this has changed your own model. At some point the two models will be in almost perfect synchrony. At this point you will have the conscious experience of what seems like, and, indeed is, wordless communication.