Speaking and listening – interbrain communication

So I’ve been writing a lot of ‘these things bug me’ posts lately. I figured I’d put up something cool today, and save my latest rant for another post.

One of my profs sent me a cool new article on speech imaging. It’s a study conducted at Princeton, by Stephens et al.

One of the big topics in speech research is communication. I know this seems obvious, but there are a lot of studies devoted to how people perceive speech – how phonemes make words, how words have meaning, how words fit together to make a grammatical sentence; and to production, with how people pick appropriate words, pronounce the phonemes, construct grammatical sentences, and convey meaning through prosody. Already I’ve left a lot out, and made a bunch of assumptions about hotly debated topics.

Now, my lab is big on the motor theory of speech. That’s a topic for another day, but suffice to say we are very interested in how people go from perceiving to producing. Because speech is not static. We hear things and need to be able to respond very quickly, almost at the rate of unconscious action. We only speak as though we were picking words out of a lexicon and parsing them syntactically when we’re speaking an unfamiliar language, have some injury or disorder, or are in a debilitated condition. That last is why I’m holding off on a delicious whisky sour until after I’m done writing this post.

There are a bunch of ideas explaining in different way how we are able to communicate so effectively, seamlessly picking up our side of a conversation in real time, and following along with a spoken narrative even under noisy conditions or confusing accents.

Stephens et al recorded functional MRI from a participant who related an unrehearsed story in English, about an experience during a high school prom. They also recorded a similarly unrehearsed personal story from a native Russian speaker, also while recording functional MRI. This was done a few times to acquaint the participant with the procedure, and then a single story for each speaker was picked.

MRI machines make a lot of noise, so they used a clever technique with two microphones that allowed them to remove the scanner noise from the story in post-processing, without making the speech sound artificial. I expect we’ll be seeing this technique more often, as it’s useful to be able to record verbal responses.

After all that, they played the story to a bunch of listeners, and recorded their brain activity using fMRI while the listeners listened to the stories in both Russian and English.

Now, here’s the cool part. Using a moving window of -4 to -1.5 to 0 to 1.5 to 4 seconds, they compared brain activity in the speaker to brain activity in the listeners during the entire length of the story. Afterwards, the listeners were tested on their recall and comprehension.

There was, excitingly, a large overlap between active regions in the speaker and the listeners. This is cool because a number of theories of speech postulate that the same regions involved in producing speech are also involved in perceiving it. Further, they found that much of this activation in the listeners lagged behind the speaker by a few seconds, implying that there was a causal relationship – that the regions active in the speaker were, via the speech, causing the same regions to become active in the listeners. In this way, a spoken narrative can be thought of as a method for one brain to induce specific activity in another (see my previous post on us being our brains).

But even cooler, was a few regions which in the listeners were active a few seconds ahead of the speakers. There were mostly frontal regions involved in planning and other executive functions. The authors suggest this is due to anticipation on the part of the listeners, a sort of heuristic predictive action to facilitate comprehension. Indeed, those listeners which had more activity in advance of the speaker’s showed improved comprehension and recall after the experiment.

Furthermore, this was all dependent on actual understanding of the story. The only speaker-listener coupling during the Russian story was in the primary auditory regions, implying that while the listener’s brains were being activated by the sounds being heard, there was no further processing specific to the story.

Even more fun than that, when they asked the speaker to relate a new story while being scanned, and compared their brain activity patterns to this listeners from the original story (to see if there is simply a regular spatial-temporal pattern of activity while relating and listening to a narrative), they found very little activity coupling. It turns out that while the generalities of activation are there, actual activity coupling only seems to occur during shared communication.

I really look forward to seeing these results replicated. The actual analysis sounds a little tricky, but the experiment itself is simple and elegant, and if the results bear out it has some interesting implications for the study of coupled speech perception and production.

In proper service.

So, what responsibilities do scientists have?

I’ve been thinking about this, since we’re right between the anniversaries of the bombings of Hiroshima (August 6, 1945) and Nagasaki (August 9, 1945).

First, I strong suggest reading the general Wiki page on the bombings.

Second, take a look at this film footage.

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That’s the underwater detonation of either Able or Baker, 23 kiloton nuclear fission bombs.

The creation and implementation of the nuclear weapons used in WWII, and those after, would not have been possible without the collusion (I use the term intentionally) of civilian scientists with the military. People like Oppenheimer or Luis Alvarez, while being patriotic Americans, partly viewed the creation of the bombs as an intellectual challenge. Others, such as Edward Teller, were more enthusiastic.

And of course, the same was true on all sides of the wars, from the atrocities of the German scientists to the Soviets. Even Canada, whom we Canadians like to think of as generally well-intentioned, contributed substantially via the Chalk River laboratories.

Today, too, military conventional and WMD research and production would not be possible without the active contribution of scientists.

Now, science is an entirely neutral tool. It is a means of knowing – nothing more or less. As with other neutral tools, though, the uses to which it is put are rarely neutral. I like to think they are frequently positive – vaccination, for example, or space exploration. The further enlightenment as to how our minds and brains function.

But much of what scientific discovery has produced is problematic at best. Nuclear weapons are a clear and obvious example. But what about fossil fuel engines and the technology required for their fuel’s extraction? The use of psychology in developing harsh interrogation and torture techniques? Bioweapons liked weaponized anthrax or sarin nerve gas?

I like to think science will be used to solve many of these problems. By this, I reject the primitivist solution, especially to environmental problems, which would ask us to dismantle everything and return to the lifestyles of our early ancestors. There is nothing to be gained by that, to my mind. I think the benefits of the modern world outweigh any sort of vague ‘harmony with nature’ that lifestyle would bring us.

Instead, I think genetic engineering, the development of alternative forms of energy, and green technologies will solve many of the problems which science has also been used to bring about.

But this leaves one big problem left – scientific participation in military technologies. Such technologies, unlike nuclear or coal power, are not two-edged swords. They are intended for a single purpose which ought to be anathema to a civilized society.

Doctors and lawyers and other professions have formal codes of ethics. These are fairly lax – doctors and psychologists have assisted in torture in American prison facilities, for example. These codes also hold no bounds over military doctors or psychologists – they only have effect if such people wish to work in a civilian setting.

True, enforced ethics codes are a fairly recent invention. Nothing formal guiding research ethics existed prior to the Nuremberg Code or the Declaration of Geneva. The Declaration of Helsinki, which codified the proper ethics involved in conducting research with human subjects, was originally drafted in 1964 and not really implemented until the revision in 1975.

Think about that. Given the length of time it takes for policy changes, especially things like a code of conduct, to become a part of the culture they’re concerned with, one could reasonably say there was no strong base for ethics in human research until the late 1970s. Problems still occur today – imagine what it was like then, when there was no formal concern for individual self-determination, when there was no concern for informed consent.

But other scientists still have no formal code of ethics dealing with the outcomes of their research, unless they deal with human or animal experimentation. True, there are codes of conduct dealing with plagiarism and misconduct, but none dealing with questions like ‘will this be used to kill people?’ or ‘will this poison this ocean?’

I’m not trying to lay a lot of blame at the feet of scientists. Much of the time the products of research have multiple applications, some of which may not be intended by their discoverers. Scientific findings are frequently misused, misunderstood, misstated, or made up to support particular political, social, or ideological positions (See Bad Science for some good examples).

My point is that scientists have a great deal of power through their findings. Anyone holding power needs to be careful how they wield it. Should Oppenheimer and his colleagues have refused to develop nuclear weapons?

It’s not an easy answer. They felt they were in a race with the Soviets and the Nazis, with the fate of the free world at stake. They lived in an age where the claims of nationalism and racism were not questioned in the way they are today. But I think they should have questioned themselves more than they did – the decision to drop the second bomb on Nagasaki was partly theirs.

Science can be, I believe, one of the greatest tools for good that humans possess. It can grant us independence from the vagaries and vicissitudes nature, from disease, from decrepitude. I think the scale of its view can help deliver us from petty intraplanatary regionalism. That the international communication and collaboration which facilitates it can be used to break down political barriers.

But scientists need to think about it. We do not have the luxury, any more than do soldiers or doctors, of simply going along with things. We must think about the uses to which our discoveries will be put, and work to make sure they are not misused.

Plasticity and Popular Science

So I’m reading “The Brain That Changes Itself” by Norman Doige. I’m liking it more now I’m getting into it, but there’s a few things bothering me about it and I thought I’d share, since at least some of them are things that bother me about popular science in general.

In the interest of fairness I’ll admit to being biased against the author from the start. He’s got a degree in psychoanalysis and apparently has a practice in it too. I didn’t even know you could get degrees in that anymore, but he seems to be on the older side. Psychoanalysis is a good part of the reason scientists often don’t take psychology seriously – even psychologists, while acknowledging how it really got their discipline going, hate the fact that it colours their entire field.

There are lots of concepts from psychoanalysis that have been very hard to discard over the years, since they’ve been around enough to become ‘common sense’. Repressed memories, for example. There’s really little evidence for their existence. If anything, people with traumatic experiences tend to relive them through flashbacks and the like. The idea of repressed memories, and psychoanalytic techniques like guided recall under hypnosis, led to the whole Satanic ritual abuse phenomenon in the 80s. We know that those conditions are perfect for creating or changing existing memories. Some very simple studies have shown this, whereby people are asked leading questions about their memories.

“Do you remember hugging Bugs Bunny at Disneyland?”

Plenty of people will answer yes to this, despite it not being possible. It gets much worse when the question is being asked during moments of emotional stress, hypnosis, or other moments when we’re open to suggestion.

But because Freud went on about repressed memories it’s common wisdom that they exist. And that’s not even getting into his sexual stuff.

So I don’t like the way Doige constantly attributes ideas as original to Freud, like a Marxist would to Marx. But that’s not my primary complaint.

It’s that he wants a Narrative. And it’s that most annoying of popsci Narratives, the ‘plucky revolutionary scientist is belittled for his ideas but bravely makes life better for a few daring clients.’

Personally, I think Kuhn needs to take a share of the blame for this. His idea of the structure of scientific revolutions, that all advances are made by the existing paradigm being broken by a new paradigm promoted by a tiny minority of visionaries, has been the bane of every skeptical scientist’s existence. Every homeopath, every UFOer, every basement crank now thinks the only reason their brilliance isn’t being recognized is because the dominant paradigm resists change.

Science does have a certain amount of inertia. Any idea which challenges established ideas does have a bit of an uphill battle. This is not necessarily a bad thing. Many, if not most, ideas turn out to be wrong. The established ones have resisted change not solely due to hidebound scientists but because they’re fairly well-supported and the evidence against them is not sufficiently compelling to force a change.

I’ll give two examples that get bandied about a fair bit.

In 1982 Drs. Barry Marshall and Robin Warren of Perth discovered that H. pylori was the cause of peptic ulcers, not stress. There’s a famous story (true) about Dr. Marshall drinking a beaker of the cultured bacterium to prove it was the cause. So – plucky duo prove cause of illness in face of doubting Thomas scientific community.

Except that the groundwork was already there. Though a study in 1954 failed to find stomach bacteria, studies through the 1970s found evidence for pathenogenic stomach bacteria. While there was opposition to Marshall and Warren’s claims, after several other groups were able to replicate their findings independently (one of science’s major modern protections against cranks) they became generally accepted. Except among much of the public, of course, where the idea that ulcers are caused by stress is still pretty common.

A second example concerns continental drift. Even until the 1960s there was no real acceptance of the theory of continental drift or plate tectonics. As soon as fairly accurate coastal maps of the continents became available, various people noted how they looked as though they ought to fit together. Plants and animals on each continent, a number of which are closely related, supported the idea. Some people suggested the Earth was expanding, but this was not hugely difficult to falsify. Others stated that the continents had been pulled apart by gravity, or the force of the Earth’s rotation, or other forces.

Alfred Wegener came up with the idea of ‘continental drift’, and provided some evidence that it had occurred. But because he couldn’t explain how it had occurred, it remained a hypothesis not widely accepted. But people kept at it, evidence accumulated, and eventually there was enough physical knowledge of the continents and the discovery of oceanic crust and the churning of the mantle gave a workable explanation.

So it’s not as though lone geniuses came up with any of this. They worked hard, came up with evidence that meshed with other independent findings, and eventually their findings were accepted. But if they hadn’t had enough high quality evidence – if their findings had never agreed with the findings of others – then they wouldn’t have been accepted.

The book also takes some potshots at horrible localizationalists and their insistence that specific regions of the brain perform particular functions and goes on about how contrary to their dogmatic beliefs, the brain isn’t a machine or a computer. It’s something of a strawman. While there have certainly been a large number of people who have rejected brain plasticity up until recently, as Doige goes through the book he keeps providing accounts of a lot of scientists, including some of the giants of neuroscience like Wilder Penfield and Donald Hebb, who didn’t take that view. And he ignores some of the things he himself presents which show that under normal conditions there are local functional regions common to all humans, and that after childhood brains become comparatively hardwired.

He also seems to tell a lot of his stories starting in the 50s and 60s, and rarely talks about anything later than the early 90s. Given the book was written in 2007 this is a bit strange. The book’s thesis is that the brain is this great changeable organ, but this view is not really disputed among modern neuroscientists. He keeps taking swings at the ideas of decades past while presenting his scientists as modern-day mavericks, and it’s a bit strange to read.

The book’s set as a series of amazing vignettes showing the miraculous theories and inventions of various scientists, which is also not guaranteed to win my affections. Nor is the NYT blurb ‘the power of positive thinking finally gains scientific credibility’, the parsing of which would take me another post.

All that being said. If you can ignore the author getting in the way of the book, and the emotionally-tinged anecdotes, it’s actually a pretty interesting look at people working with brain plasticity and how it can be used to help people with cognitive of sensory problems.

But there’s better popular science writing out there, much of it written by actual scientists.

Libet and Dennett: Our brains and ourselves.

So. There’s this thing that bugs me whenever consciousness, the self, and free will come up in discussion or readings.

Let me explain using an old experiment by Benjamin Libet. There were two that commonly get talked about, but I’m going to focus on the second. In this study, participants were hooked up to electrodes and asked to watch a turning disc with a dot on it. Whenever they felt like it, they were to lift a finger and note the position of the dot.

What they expected to find was a burst of EEG activity at around the same time the participants made the decision to lift their finger. There’s some timing issues about intention -> motion transmission times, but that’s generally what they expected.

What they found was a burst of activity about 300ms before the participants consciously reported creating the intention to move. There’s a lot of dispute over the experimental setup, since it’s difficult to be sure of fractions of a second with this sort of self-report paradigm. But a lot of the discussion takes the findings as valid.

What does it mean? It seems like the decision to move was made independently of any intention on the part of the participants – their brains decided to move their finger, and only informed them shortly afterwards. It’s created a lot of talk about free will, and how free we are if our decisions are made before we’re aware of making them – if we are in fact subservient to our brains.

Of course we are.

It’s that sort of nonsense that ought to bother monists in general and neuroscientists in particular. There’s this strange insistence in our society, creating by centuries of dualism and the belief in an immortal soul riding a corporeal shell, that we’re somehow divisible from our bodies and brains. Our brains are us. You cannot say our brains have made the decision before we have, since we are our brains. The fact that you weren’t consciously aware of it makes little difference.

Think about when you speak. Unless you’re making an effort to be articulate, words just come out. How often are you consciously aware of each specific word you’re about to use in a sentence? If you’re speaking your native language, not very. This is why second languages often sound halting – because you’re actually having to consciously pick words rather than just letting them come out as appropriate. Speech is a strange thing, in that it’s consciously directed, and you can switch in and out of conscious control, but otherwise it’s largely unconscious. Sort of like driving after you’ve become experienced.

In fact, there’s a lot of evidence that expertise involves the gradual transfer of control to unconscious function. This is true of both physical skills, and to a certain extent knowledge/usage skills. Even something as typical as typing in a password becomes unconscious after while. Think of things where you have the same login but different passwords, one of which you use more. How often do you type in the more frequent password once you’re entered the less frequent username?

I’ll bring this up a lot, but I think Daniel Dennett has some valuable things to say here. He has written about the ‘multiple drafts’ theory of consciousness, in which information is shunted back and forth in parallel between different modules in a very messy, non-linear fashion. He feels Libet’s experiment is folly because it tries to lock down a single linear progression of action from intention to motion, when in fact things are not so straightforward. This combines with another idea of his, that the self is a ‘narrative centre of gravity’. You can’t locate the physical self, any more than you can locate the centre of gravity of a hoop – it exists, mathematically, and it has properties, but there’s nothing physical there. He sees our consciousness and sense of self as a sort of byproduct of complex mental events, a way to make sense of sensory input, mental manipulation of information, and direct output.

It’s a nice theory. I think Libet’s experiment doesn’t fit his critique exactly – people get tied down into timing issues, but as far as I can tell it doesn’t make much of a difference. Libet’s experiment and Dennett’s theory explain a lot about how we can be fooled by various illusions or cognitive errors, as different drafts of the story come together without any conscious direction. The metaphors may get a bit mixed, but it comes down to my initial point. We’re our brains.

People will say ‘my body’s out to get me,’ or ‘my body has a mind of its own.’ Nonsense. You are your body, and you are your mind. You just aren’t aware of it all the time.