Fall prevention in older people — Stephen Lord at HCSNet

Sway meter, subject on foam

Daniel isn’t the only guy at Neuroanthropology who gets to go to good conferences; last week, while in the throes of a cold brought on by fieldwork with the 15-and-under Sydney city select rugby team, I got to go to the HCSNet Workshop on Speech, Perception and Action held at Western Sydney University.

HCSNet is funded by the Australian Research Council to promote research on human communication. I only got to go to the second day of the two-day conference (because I was cooking meals for 20 hungry rugby hopefuls the first day), but I saw a number of great presentations, including talks by Catherine Best, MARCS Auditory Laboratories, UWS, Beatriz Calvo-Merino, University College London, and Stephen Lord, Prince of Wales Medical Research Institute. I’ll blog soon on Dr. Calvo-Merino, one of the high points of the day, but today I want to make some notes on Prof. Lord’s fascinating research and talk.

Prof. Lord heads the Falls and Balance Research Group. Visit the group’s website for publications and some great information about risk factors for falling. At the conference, Lord discussed the group’s extensive applied research examining different factors that contribute to older people falling and experimental interventions to decrease the contribution of any single factor. The project has created a screening procedure for use by general practitioners to evaluate an older person’s likelihood of falling.

As regular readers know, I’m particularly interested in the way humans maintain equilibrium (see earlier posts, Kids falling down and Equilibrium, modularity, and training the brain-body, and Daniel’s post of some great parkour video, Free Running and Extreme Balance). In the longer of these posts (Equilbrium, modularity…), I specifically discussed how the ’sense of balance’ is actually a much more complex synthesis of multiple sensory inputs, both exteroception (perception of the world) and interoception (perception of the self).

Synesthesia & metaphor — I’m not feeling it

Wired online carried a story recently on a talk by ‘neuroscientist extraordinaire’ V.S. Ramachandran, one of the folks responsible for a lot of creative thinking in the brain sciences. Brandom Keim writes on a recent talk Ramachandran gave at the World Science Festival in a story, Poetry Comes from Our Tree-Climbing Ancestors, Neuroscientist Says. While I typically find his stuff both fascinating and resonant, this particular piece left me unpersuaded.

Normally, I might take issue with the sloppy logic of the title (’poetry’ coming from ‘tree-climbing ancestors’ being a dangerous conflation between non-proximate contributing factors and eventual effects — you could just as logically say that ‘poetry comes from spinning disk of post-stellar material in proto-solar system’…), but I’ve got bigger fish to fry: synesthesia.

Rmachandran’s work on synesthesia is excellent; for example, his piece with in Neuron on synesthesia is essential reading, and the piece he co-authored on the condition in Scholarpedia is my source for a fair bit of what I will write. The problem is that I don’t think that synesthesia is a good metaphor for, well, metaphor.

Although there may be some ways that metaphor is like synesthesia, when we add up the pros and cons, synesthesia as a metaphor for metaphor may not help us too much to understand the latter, and I seriously doubt that the two are linked in a more profound causal fashion (like a ‘gene’ for both synesthesia and metaphor). Similarly, attention-based failure to perceive something may be like blindness, but using one to try to explain the other is futile. In other words, not all metaphors are equally useful, and I’m concerned that the synesthesia metaphor for metaphor might do more harm than good.

Lessons from sarcasm (so useful…)

The New York Times ran a story on brain imaging studies of sarcasm, The Science of Sarcasm (Not That You Care), by Dan Hurley. That’s right — that favourite rhetorical tool of the snarky adolescent has been subjected to brain imaging studies. The Pearson Assessment video — of an actor delivering the same lines twice, once sincerely, and once dripping sarcasm — is fun. I found myself thinking that I could have been MORE sarcastic.

Hurley, the author of the NYTimes article, does a pretty good job of explaining things, although I think that the idea that perceiving sarcasm requires a ‘theory of mind,’ alluded to in the article, is a bit of a problem — but I have that issue with a lot of the ‘theory of mind’ material because I think it ‘over-cognizes’ social perception (that’s my own issue, so I won’t dwell on it). Hurley discusses the research of Katherine P. Rankin, using MRI scans and the Awareness of Social Inference Test, or Tasit. I have looked on the website for the Memory and Aging Center of UCSF, and through PubMed and EurekAlert, but I can’t find the original report on this research (please post a comment if you know where it is).

“I was testing people’s ability to detect sarcasm based entirely on paralinguistic cues, the manner of expression,” Dr. Rankin said. What seems particularly interesting is that the part of the brain which seemed to be linked to sarcasm — damage to it by dementia impeded the ability to recognize sarcasm — was in the right hemisphere, not usually associated with language or social interaction (which are generally associated with the left hemisphere). Instead, sarcasm seemed to require activity in ‘a part of the right hemisphere previously identified as important only to detecting contextual background changes in visual tests.’

Children integrating their senses

Two of the pieces that I have wanted to discuss appear together in Current Biology, both on evidence of sensory integration in adults compared to their integration in children. Nature News carried a story about both articles, One sense at a time, by Matt Kaplan. As Kaplan explains, the research generally supports the idea that: ‘Adults readily integrate sight, sound, smell, taste and touch in their everyday lives without a second thought. But research is revealing that this is not the case with children. Two new studies hint that children under the age of eight only use one sense at a time to judge the world around them.‘

As I started to discuss in an earlier piece on human equilibrium (long ago — still working on parts two and three), adults learn how to weight different sensory information depending on context and the task at hand, evaluating one stream against another if they conflict. When confronted with two contradictory impressions from different senses — such as video of a person saying one thing and audio of a slightly different word — adult sensory systems figure out a way to integrate the sense world, sometimes creating ’sensory’ compromises or syntheses. The ability to integrate sensory information is fundamental to normal human functioning, but it tends to undermine certain conceptions of brain ‘modularity,’ as I argued in the earlier post.

But with these two articles, I want to explore something a bit different, so I’m going to tackle each one individually, and then reflect on one issue that I think is important: the tendency to see child development in a teleological framework, that is, as an incomplete version of an adult system rather than as a deployment of the child’s distinctive neural resources. Before you click on ‘read more’ below though, be warned; this piece is a bit long…

Perception and Politics

Do we really know what’s going on? Or do we just see what we want to see?

The Data

Larry Bartels, director of the Center for the Study of Democratic Politics at Princeton, has an op-ed Who’s Bitter Now? which shows us a stereotype of rural voters in action. His argument? “Small-town people of modest means and limited education are not fixated on cultural issues. Rather, it is affluent, college-educated people living in cities and suburbs who are most exercised by guns and religion. In contemporary American politics, social issues are the opiate of the elites.”

Bartels sets out to actually define the “small-town working class,” making less than $60,000, living in small towns or rural areas, never graduated from college. He compares them to cosmopolitan voters, college graduates who live in the suburbs or cities making $60,000 or more. The first group makes up about 16 percent of voters, the second 13 percent.

Small-town, working-class people are more likely than their cosmopolitan counterparts, not less, to say they trust the government to do what’s right. In the 2004 National Election Study conducted by the University of Michigan, 54 percent of these people said that the government in Washington can be trusted to do what is right most of the time or just about always. Only 38 percent of cosmopolitan people expressed a similar level of trust in the federal government.

Do small-town, working-class voters cast ballots on the basis of social issues? Yes, but less than other voters do. Among these voters, those who are anti-abortion were only 6 percentage points more likely than those who favor abortion rights to vote for President Bush in 2004. The corresponding difference for the rest of the electorate was 27 points, and for cosmopolitan voters it was a remarkable 58 points. Similarly, the votes cast by the cosmopolitan crowd in 2004 were much more likely to reflect voters’ positions on gun control and gay marriage.

Bartels finishes by telling us the larger pattern behind it all. “It is true that American voters attach significantly more weight to social issues than they did 20 years ago. It is also true that church attendance has become a stronger predictor of voting behavior. But both of those changes are concentrated primarily among people who are affluent and well educated, not among the working class.”

The Interpretation

So why the problem in perception? Is it because he clings to a stereotype, as Bartels seems to suggest?

Nicholas Kristof’s column today, Divided They Fall, offers us better than a yes/no. He wants to take on “how our biases shape our understanding of reality.” Of course the candidate you favor won the debate last time… Or did he or she?

‘Blind to change’ or just ‘mostly blind’?

The New York Times Science section has a recent article, Blind to Change, Even as It Stares Us in the Face, by Natalie Angier (you can access it without charge by signing up to their site). The article follows along some of the lines laid out by Jeremy Wolfe of Harvard Medical School, at a symposium on Art and Neuroscience.

Angier discusses Wolfe’s use of Ellsworth Kelly’s ‘Study for Colors for a Large Wall’ to illustrate what is typically called ‘change blindness’: ‘the frequent inability of our visual system to detect alterations to something staring us straight in the face.’ Kelly’s painting is an 8×8 grid of coloured squares, and Wolfe apparently showed repeatedly slides of the picture, sometimes with the colours of squares altered. When he first showed the slide, Angier writes: ‘We drank it in greedily, we scanned every part of it, we loved it, we owned it, and, whoops, time for a test.’ After the test, when the audience was thoroughly uncertain about its ability to recall even the basic patterns of colours; ‘By the end of the series only one thing was clear: We had gazed on Ellsworth Kelly’s masterpiece, but we hadn’t really seen it at all,’ Angier reports.

Change blindness is a fun phenomenon to put into research design. Researchers get away with some really amazing manipulations without their subjects recognizing them. Some experiments report that subjects fail to notice, as Angier details, whole stories of buildings disappearing or that ‘one poor chicken in a field of dancing cartoon hens had suddenly exploded.’

Dr. Wolfe also recalled a series of experiments in which pedestrians giving directions to a Cornell researcher posing as a lost tourist didn’t notice when, midway through the exchange, the sham tourist was replaced by another person altogether.

I’ve also seen discussions of experiments in which subjects watched a videotape and failed to notice a guy in a gorilla suit walking through the middle of the video because they were asked to pay attention to other details.

But is it that we’re blind to change, or that we just trust the world to remember for us, and we’re really good at getting the information we need?

Smell, fear and sensory learning

Wen Li, James D. Howard, Todd B. Parrish, and Jay A. Gottfried have a fascinating article in the most recent edition of Science, ‘Aversive Learning Enhances Perceptual and Cortical Discrimination of Indiscriminable Odor Cues.’ The researchers trained subjects to discern between the aroma of chemicals that initially were indistinguishable using electric shocks (!) coupled with one of the two aromas. The research is a great example of perceptual learning, a form of neural enculturation that I think is absolutely essential to understanding cultural difference but little appreciated in anthropology.

Subjects in the experiment were given a test of their ability to discern between very closely related chemicals: ‘On each trial, subjects smelled sets of three bottles (two containing one odorant, the third containing its chiral opposite) and selected the odd stimulus.’ Before the training, subjects selected the odd odor out 33% of the time — no better than random. After the repeated association of one chemical with shocks, subjects’ ability to discriminate the smells improved markedly, showing that negative reinforcement training could ‘enhance perceptual discriminability between initially indistinguishable odors.’ Moreover, the neural representation of the smells changed, as found with fMRI.

From their abstract:

We combined multivariate functional magnetic resonance imaging with olfactory psychophysics to show that initially indistinguishable odor enantiomers (mirror-image molecules) become discriminable after aversive conditioning, paralleling the spatial divergence of ensemble activity patterns in primary olfactory (piriform) cortex. Our findings indicate that aversive learning induces piriform plasticity with corresponding gains in odor enantiomer discrimination, underscoring the capacity of fear conditioning to update perceptual representation of predictive cues, over and above its well-recognized role in the acquisition of conditioned responses. That completely indiscriminable sensations can be transformed into discriminable percepts further accentuates the potency of associative learning to enhance sensory cue perception and support adaptive behavior.

Wednesday Round Up #4

Books

Dr. Ginger Campell and her Brain Science Store
Ginger provides a handy Amazon collection of the books covered in her podcasts

Greg Mortensen and David Oliver Relin, Three Cups of Tea: One Man’s Mission to Promote Peace… One School at a Time
Building schools amid the Taliban, Americans and more…  Recently covered in the Diane Rehm show.  800+ reviews on Amazon, averaging in at the max 5 stars 

Brian Fagan, The Great Warming: Climate Change and the Rise and Fall of Civilizations
Drought is our great historical enemy, especially in dense populations… Recently reviewed in the NY Times 

Sandra Blakeslee & Matthew Blakeslee, The Body Has a Mind of Its Own: How Body Maps in Your Brain Help You Do (Almost) Everything Better
One reviewer: “The brain and the body are not separate entities, but are intertwined, interdependent, and interfunctional. Understanding this fact is essential to understanding how and why body maps work. This book explains that lucidly.” 

Stephen Kern, A Cultural History of Causality: Science, Murder Novels, and Systems of Thought
Literary murder and social history—how we view the causes of ourselves

Melody Petersen, Our Daily Meds: How the Pharmaceutical Companies Transformed Themselves into Slick Marketing Machines and Hooked the Nation on Prescription Drugs
Pharmaceuticals killing people, and companies marketing them more.  See an illuminating review here  

Vision 

Cognitive Daily, Fun With Point-Light Displays—And What That Says About The Visual System
Creating order out of dots… includes some good QuickTime videos

Mixing Memory, Language, Neuroscientific Evidence for the Influence of Language on Color Perception
Critique of imaging, importance of evidence, and our visual system

General 

Cordelia Fine, Will Working Mothers’ Brains Explode? The Popular New Genre of Neurosexism
Critique of the at times popular view that gender differences are “hard wired”

Brandon Keim, Brain Scanner Can Tell You What You’re Looking At
Functional imaging and a good computational program can “decode” the different photographs people see, reconstructing the content.   Worth a look!

Wednesday Round Up #3

Race 

The New York Times, How Race Is Lived In America
Series of articles focused on how race relations are defined by “daily experience, in schools, in sports arenas, in pop culture and at worship, and especially in the workplace”

American Anthropological Association, RACE: Are We So Different?
“Looking through the eyes of history, science and lived experience, the RACE Project explains differences among people and reveals the reality – and unreality – of race.”

The New York African Burial Ground
“Return to the past to build the future”
Also check out the lead researcher’s report, “An Examination of Enslaved Lives, A Construction of Ancestral Ties”

Jennifer Eberhardt, Imaging Race (pdf)
American Psychologist article on brain imaging and the “social psychological responses associated with race”

Barack Obama’s Speech on Race
Full transcript here; Video, with comments across the spectrum, here
And for those people coming here, seeking more commentary on Obama’s speech, I now have a post on Obama and Race.

Embodiment & Sense Making

20/20, Blind People Who Interact with the World like Dolphins & Bats
Humans can echolocate!  Absolutely amazing.

Mind Matters, Thinking With The Body
Reading, Movement, and Embodied Cognition

CF Kurtz & DJ Snowden, The New Dynamics of Strategy: Sense-making in a Complex and Complicated World
Challenging three basic assumptions—order, rational choice, and intent—in decision making

Trust your hand, not your eyes

Daniel forwarded me a link to the story, The Hand Can’t Be Fooled, Study Shows, from Science Daily. The story is a short piece about research by Ben-Gurion University of the Negev Psychologist Tzvi Ganel and his colleagues on how the “Ponzo” illusion affects visual perception. The “Ponzo” illusion occurs when two equal line segments appear to be of different lengths because they are superimposed on a pair of converging lines; like two lines hovering over train-tracks disappearing into the distance appear to be of different lengths, as you can see from this illustration I took from the BBC.

Ganel and his colleagues ‘hooked participants’ index finger and thumb to computerized position tracking equipment and asked them to grasp the objects with their fingers. Even thought the object appeared to be larger (or smaller) than it really was, the size of their grasp reflected the object’s real rather than apparent size. For good measure, the researchers arranged the illusion so that the object that appeared to be the smaller of the two was actually the larger of the two.’

Ganel argues that the experiment provides compelling support for the ‘two visual systems’ hypothesis put forward by Mel Goodale and David Milner about a decade ago (see Goodale and Milner 1992; Milner and Goodale 1995; for an overview, see Goodale and Humphrey 2001). According to Goodale and Milner, one visual system processes input for object and color recognition, recognizes objects no matter what the perspective of the viewer, and uses conscious parts of the brain; another visual system judges spaces, movement and object trajectories in egocentric space in order to control body movement, and does not necessarily access conscious thought. I’ve written about the two visual systems hypothesis elsewhere in a book chapter that just came out (Downey 2008), so Daniel probably recognized that I’m a bit of a fan of the ‘tectopulvinar’ (motion control) visual system. (For a quick overview of the two systems, this is a good set of diagrams and explanation.)