Monday, 11 January 2010
Friday, 13 March 2009
Much of our understanding of mind-reading comes from two remarkable scientists, a teacher and his pupil: Silvan Tomkins and Paul Ekman. Tomkins was the teacher.
He was born in Philadelphia, at the turn of the last century, the son of a dentist from Russia. He was short, and thick around the middle, with a wild mane of white hair and huge black plastic-rimmed glasses. He taught psychology at Princeton and Rutgers, and was the author of "Affect, Imagery, Consciousness," a four-volume work so dense that its readers were evenly divided between those who understood it and thought it was brilliant and those who did not understand it and thought it was brilliant. He was a legendary talker.
At the end of a cocktail party, a crowd of people would sit, rapt, at Tomkins's feet, and someone would say, "One more question!" and they would all sit there for another hour and a half, as Tomkins held forth on, say, comic books, a television sitcom, the biology of emotion, his problem with Kant, and his enthusiasm for the latest fad diets, all enfolded into one extended riff.
During the Depression, in the midst of his doctoral studies at Harvard, he worked as a handicapper for a horse-racing syndicate, and was so successful that he lived lavishly on Manhattan's Upper East Side. At the track, where he sat in the stands for hours, staring at the horses through binoculars, he was known as the Professor. "He had a system for predicting how a horse would do based on what horse was on either side of him, based on their emotional relationship," Ekman remembers. If a male horse, for instance, had lost to a mare in his first or second year, he would be ruined if he went to the gate with a mare next to him in the lineup. (Or something like that-- no one really knew for certain.) Tomkins believed that faces--even the faces of horses--held valuable clues to our inner emotions and motivations.
He could walk into a post office, it was said, go over to the "Wanted" posters, and, just by looking at mug shots, tell you what crimes the various fugitives had committed. "He would watch the show 'To Tell the Truth,' and without fault he could always pick the person who was lying and who his confederates were," his son, Mark, recalls. He actually wrote the producer at one point to say it was too easy, and the man invited him to come to New York, go backstage, and show his stuff." Virginia Demos, who teaches psychology at Harvard, recalls having long conversations with Tomkins. "We would sit and talk on the phone, and he would turn the sound down while Jesse Jackson was talking to Michael Dukakis, at the Democratic National Convention. And he would read the faces and give his predictions on what would happen. It was profound."
Paul Ekman first encountered Tomkins in the early 1960's. Ekman was then a young psychologist, just out of graduate school, and he was interested in studying faces. Was there a common set of rules, he wondered, that governed the facial expressions that human beings made? Silvan Tomkins said that there were. But most psychologists said that there weren't. The conventional wisdom of the time held that expressions were culturally determined--that we simply used our faces according to a set of learned social conventions.
Ekman didn't know who to believe. So he traveled to Japan, Brazil, and Argentina--and to remote tribes in the jungles of the Far East--carrying photographs of men and women making a variety of distinctive faces. To his amazement, everywhere he went people agreed on what those expressions meant. Tomkins was right.
Not long afterwards, Tomkins came to visit Ekman at his laboratory in San Francisco. Ekman had just tracked down a hundred thousand feet of film that had been shot by the virologist Carleton Gajdusek in the remote jungles of Papua New Guinea. Some of the footage was of a tribe called the South Fore, who were a peaceful and friendly people. The rest was of the Kukukuku, who were hostile and murderous and who had a homosexual ritual where pre-adolescent boys were required to serve as courtesans for the male elders of the tribe. For six months, Ekman and his collaborator, Wallace Friesen, had been sorting through the footage, cutting extraneous scenes, focusing just on close-ups of the faces of the tribesmen, in order to compare the facial expressions of the two groups. Ekman set up the camera. Tomkins sat in the back. He had been told nothing about the tribes involved; all identifying context had been edited out. Tomkins looked on intently, peering through his glasses.
At the end, he went up to the screen and pointed to the faces of the South Fore. "These are a sweet, gentle people, very indulgent, very peaceful," he said. Then he pointed to the faces of the Kukukuku. "This other group is violent, and there is lots of evidence to suggest homosexuality." Even today, a third of a century later, Ekman cannot get over what Tomkins did. "My God! I vividly remember saying, "Silvan, how on earth are you doing that?" Ekman recalls. "And he went up to the screen and, while we played the film backward, in slow motion, he pointed out the particular bulges and wrinkles in the face that he was using to make his judgment. That's when I realized, 'I've got to unpack the face.' It was a gold mine of information that everyone had ignored. This guy could see it, and if he could see it, maybe everyone else could, too."
Ancient brain circuits light up so we can judge people on first impressions
'Its almost instantaneous and you can't stop doing it': neuroscientists match scans to human decision making
Ancient neural circuits - the amygdala and posterior cingulate cortex - are active when people form first impressions of new acquaintances.
Photograph: Daniela Schiller/New York University/Nature Neuroscience
Scientists have recorded the gentle flicker of activity that lights up the brain when we form our first impressions of people. The study shows how age-old brain circuitry that evolved to make snap decisions on the importance of objects in the environment is now used in social situations.
Brain scans taken while volunteers formed opinions of new acquaintances found activity surged in an ancient neural circuit that helps us make a rapid assessment of a person's character.
"Humans have always been engaged in making decisions on what's important and what's not, and social decision making is taking advantage of these primary systems in the brain," said Daniela Schiller, who led the study at New York University.
"Whenever you need to assign value to something, you use the same mechanism, whether it's an inanimate object or a person. It's like there's one common currency in the brain."
Previous work by neuroscientists has shown we form our first impressions well within 30 seconds of meeting people. Often, our opinion changes very little after knowing them for longer.
"When you meet a person, they might say something, or look a certain way, or behave a certain way, but you have very little information on which to form an opinion, but it is almost instantaneous and you can't withhold from doing it," said Schiller.
In the study, published in Nature Neuroscience, Schiller and scientists from Harvard University took brain scans of 19 volunteers who were asked to form a first impression of a series of fictional characters.
The volunteers were shown faces of men on a computer screen, followed by six sentences that described a mix of good and bad aspects of their character. For example, the person might have picked up his room mate's post on the way home from university, or told a fellow student they were stupid. After reading all of the sentences, the participants were asked to rate how much they liked the person on a scale from one to eight, with eight being the most likable.
Schiller's team then looked through the images from the scanner to see what brain regions had been most active while people formed their first impressions.
The scans showed that two brain regions were involved in opinion-forming, the almond-shaped amygdala, which is linked to regulating emotions, and the posterior cingulate cortex, which is active in making financial decisions and putting values on the outcomes of situations.
"Even when we only briefly encounter others, brain regions that are important in forming evaluations are engaged, resulting in a quick first impression," said Elizabeth Phelps, a co-author on the study at New York University.
Understanding the biological circuits involved with opinion forming might help scientists learn what happens when they are disrupted or fail to activate properly. "It might affect the impressions you have of others, and that could feed into the basis of your relationship with them from then on," said Schiller.
Though, Gladwell captured it well without the mumbo-jumbo in his book, Blink.
Rapid cognition is the sort of snap decision-making performed without thinking about how one is thinking, faster and often more correctly than the logical part of the brain can manage.
Gladwell's discussion of 'thin slicing' is arresting: The secret is knowing which information to discard and which to keep. Our brains are able to perform that work unconsciously; when rapid cognition breaks down, the brain has seized upon a more obvious but less correct predictor.
There are things that can be done to redirect our mind along lines more conducive to accurate thin slicing: we can alter our unconscious biases; we can change products' packaging to something that tests better with consumers; we can analyze numerical evidence and make decision trees; we can analyze all possible facial expressions and their shared meanings, then watch for them on videotape; and we can evade our biases by blind screening, hiding the evidence that will lead us to incorrect conclusions.
Friday, 6 March 2009
... or thought reading (as they say)
For the basics about multivariate fMRI "mind-reading" techniques, see the video below. Some of it is based on this 2007 Haynes et al paper from Current Biology, described in more detail following the video.
What Haynes et al have done is to ask 8 subjects to freely decide either to add or subtract two numbers, and to select among 4 options an answer corresponding to the task they chose. After repeating this process many times, the authors ran a pattern classifier on the metabolic activity recorded in the brain.
This pattern classifier was run on the unsmoothed fMRI data - smoothing is normally applied because fMRI is thought to be a relatively noisy recording technique. Critically, the use of a pattern classifier allows the use of unsmoothed data (and in fact requires it) because buried within the noise is a distributed signal reflecting the distributed neural patterns encoding the subject's intention. Such data is presumably lost in averaging/smoothing operations.
Haynes et al trained their pattern classifier (a linear support vector machine) using a "multivariate searchlight" (described here) approach. This means that for every recorded voxel, they fed the classifier information about both that voxel and those surrounding it. The classifier was trained on 87.5% of the data (using 8-fold validation), and maps were produced of the classifier's accuracy at each voxel in the brain. These "accuracy maps" were averaged across subjects to produce the following figure:
As you can see above, the results showed that intention is decodable both prior to and during the intended response in numerous regions in the prefrontal cortex. In particular, the anterior & posterior medial prefrontal cortices as well as lateral frontopolar cortex, right middle frontal gyrus, and left operculum contained information that allowed the decoding of intentions at a level significantly above chance. Intentions prior to responses were also decoded based on activity in the temporo-parietal junction, although it is not illustrated in the above figure (see the supporting online material here). Much debate focuses on the precise roles of these regions, but their involvement here would be predicted by the majority of cognitive neuroscientists.
Conspicuously absent from these maps is the intraparietal sulcus (IPS), which has been argued to reflect numerical processing. An interesting possibility is that the numerical processing accomplished by this region cannot be distinguished based on the numerical operation (addition vs. subtraction), which would support a process-independent representation of quantity. Note that this conflicts with some theories of numerical processing in the IPS.
What's fairly amazing about this work is that they used a pretty standard scanner (only 3 tesla) with a reasonable sampling time (a TR of just over 2.7s). Peter Bandettini has suggested that this unsmoothed multivariate approach would benefit from higher resolution MRI, but Haynes et al have demonstrated surprising success with much more widely-available technology.
Thursday, 5 March 2009
To reduce the severity of his seizures, Joe had the bridge between his left and right cerebral hemisphers (the corpus callosum) severed. As a result, his left and right brains no longer communicate through that pathway.
Psychology quote of the day
"Common sense and a sense of humor are the same thing, moving at different speeds. A sense of humor is just common sense, dancing."
- William James, American psychologist and philosopher (1842 - 1910)
Letting my common sense do its bit ... new study shows this ! ( why do people even bother and take all that pain, I fail to grasp ?)
Friday, 27 February 2009
Sunday, 22 February 2009
Friday, 20 February 2009
If you want to truly understand something, try to change it.- Kurt Lewin (American Psychologist)
- Interact with the environment.
- Die. (Woah! Isn't it remarkably similar to our lives)
- Store our interactions & learn from them.
- I = genes (in algae) = genes + brain (in humans)
- Understanding an algae = understanding it's genes + it's environment ; Understanding humans = understanding our genes + brain + environment
- While I evolves over generations in an algae, it evolves continually in humans