Neuroskeptic thinks he can fix science.... and I believe him.
The age at which scientists make important discoveries has been increasing.
Blue light for cognitive enhancement?
I did WHAT in my sleep??? The ethical complications of sleep disorders from Bering in Mind.
Campaign for the Future of Higher Education.
Tuesday, May 24, 2011
Tuesday, May 17, 2011
A reverse decline effect for RSVP?
Last week I attended the Vision Sciences Society annual meeting in Florida. Good times, good science. Although I don't use this blog for talking about my own research or field, I was struck by a talk from Molly Potter that was germane to this blog. (In full disclosure, Molly was the chair of my PhD committee, a personal hero of mine, and a large influence on my thinking).
In the 1960s and 1970s, Prof. Potter sought to study the temporal limits of complex visual processing. As our eyes move multiple times per second, the visual input we receive is constantly changing. To emulate this process, she developed the technique of rapid serial visual presentation (RSVP). In this method, one presents a participant with a stream of photographs, one after another, for a very brief time (half a second or less per picture). She found that when you give a participant a target scene (either by showing the picture or describing the picture), the participant can detect the presence or absence of this picture even when the pictures are presented for a tenth of a second each! Below is an example of one of these displays. Try to find a picture of the Dalai Lama wearing a cowboy hat.
Pretty cool, huh?
In her new research, Prof. Potter was trying to determine how much faster the visual system can be pushed by presenting RSVP steams that were only 50, 33 or even 13ms per picture. Here is a graph adapted from my notes at her talk:
Even at 13 ms per image, participants were performing at about 60% correct, and by 80ms per image, they were nearly perfect.
"Huh" I thought to myself during the talk, "this is really high performance. It seems even higher than performances for longer presentation times that were in the original papers".
So back in Boston, I looked up the original findings. Here is one of the graphs from 1975:
So, participants in 1975 needed 125ms per picture to reach the same level or performance that modern participants can perform with 33ms/picture.
I've complained a bit here about the so-called "decline effect", the phenomenon of effect sizes in research declining over time. The increased performance for RSVP displays can be seen as a kind of reverse decline effect.
Why?
In 1975, the only way to present pictures at a rapid rate was through the use of a tachistoscope. Today's research is done on computer monitors. Although the temporal properties of CRT monitors are well-worked out, perhaps these two methods are not fully equivalent. On the other hand, compared to 1975, our lives are full of fast movie-cuts, video games and other rapid stimuli, and so the new generation of participants may have faster visual systems.
In the 1960s and 1970s, Prof. Potter sought to study the temporal limits of complex visual processing. As our eyes move multiple times per second, the visual input we receive is constantly changing. To emulate this process, she developed the technique of rapid serial visual presentation (RSVP). In this method, one presents a participant with a stream of photographs, one after another, for a very brief time (half a second or less per picture). She found that when you give a participant a target scene (either by showing the picture or describing the picture), the participant can detect the presence or absence of this picture even when the pictures are presented for a tenth of a second each! Below is an example of one of these displays. Try to find a picture of the Dalai Lama wearing a cowboy hat.
Pretty cool, huh?
In her new research, Prof. Potter was trying to determine how much faster the visual system can be pushed by presenting RSVP steams that were only 50, 33 or even 13ms per picture. Here is a graph adapted from my notes at her talk:
Even at 13 ms per image, participants were performing at about 60% correct, and by 80ms per image, they were nearly perfect.
"Huh" I thought to myself during the talk, "this is really high performance. It seems even higher than performances for longer presentation times that were in the original papers".
So back in Boston, I looked up the original findings. Here is one of the graphs from 1975:
So, participants in 1975 needed 125ms per picture to reach the same level or performance that modern participants can perform with 33ms/picture.
I've complained a bit here about the so-called "decline effect", the phenomenon of effect sizes in research declining over time. The increased performance for RSVP displays can be seen as a kind of reverse decline effect.
Why?
In 1975, the only way to present pictures at a rapid rate was through the use of a tachistoscope. Today's research is done on computer monitors. Although the temporal properties of CRT monitors are well-worked out, perhaps these two methods are not fully equivalent. On the other hand, compared to 1975, our lives are full of fast movie-cuts, video games and other rapid stimuli, and so the new generation of participants may have faster visual systems.
Sunday, May 15, 2011
Growing PhDs "like mushrooms"
If you have been following this blog, it comes as no surprise that I frequently worry about the state of the university system. I believe there are structural problems in the system that are a disservice to students (both at the undergraduate and graduate levels) as well as staff (particularly adjuncts and non-tenure track faculty, but also to junior tenure-track professors as well).
Recently, Nature published a series of opinion articles on the over-production of PhDs in the sciences. We are producing too many people who are apprenticed in a career path that can accommodate only a fraction of them.
As a result, we are spending longer in graduate school and in our postdocs, but the number of people passing through the needle eye to professorship is shrinking as tenure-track jobs get replaced with temporary and adjunct positions. In 1973, 55% of US biology PhDs secured tenure-track positions within six years of completing their degrees, and only 2% were in a postdoc or other untenured academic position. By 2006, only 15% were in tenured positions six years after graduating, with 18% un-tenured. This largely fits with my perception: it has been seven years since I began graduate school, and considering my incoming class, we are evenly spread across remaining in school, having a post-doc and getting a job in industry. Not one of us currently has a tenure-track faculty position. Something must be very broken in the system for prospects to be this bleak for graduates of a top-five department.
So why doesn't the market change such that supply meets demand? Essentially, it's that the system runs on cheap graduate and postdoctoral labor. "Yet many academics are reluctant to rock the boat as long as they are rewarded with grants (which pay for cheap PhD students) and publications (produced by their cheap PhD students). So are universities, which often receive government subsidies to fill their PhD spots." In fact, faculty members who are reluctant to perpetuate this cycle are punished in grant review, writing in costs for a research scientist at $80,000 per year when others have the same work done by a postdoc at $40,000 per year.
So, how did we get here? Part of the issue has to be that more people are going to college than ever before and the university system does not properly scale to the demand. In the US in 1970, only 11% of people over the age of 25 had a bachelor's degree, but this number had climbed to 28% by 2009. So more graduate students, postdocs and adjuncts are being used to teach the courses to accommodate all of these new students. While some claim that it is just too expensive to have tenure-track faculty teaching all of these courses, one must also consider the recent trend towards massive salaries for university professors.
Actually, if anyone could explain university economics to me, I'd be grateful.
And where do we go from here? Personally, I love the suggestions made by William Deresiewicz in this fantastic article. Particularly, "The answer is to hire more professors: real ones, not academic lettuce-pickers."
Recently, Nature published a series of opinion articles on the over-production of PhDs in the sciences. We are producing too many people who are apprenticed in a career path that can accommodate only a fraction of them.
As a result, we are spending longer in graduate school and in our postdocs, but the number of people passing through the needle eye to professorship is shrinking as tenure-track jobs get replaced with temporary and adjunct positions. In 1973, 55% of US biology PhDs secured tenure-track positions within six years of completing their degrees, and only 2% were in a postdoc or other untenured academic position. By 2006, only 15% were in tenured positions six years after graduating, with 18% un-tenured. This largely fits with my perception: it has been seven years since I began graduate school, and considering my incoming class, we are evenly spread across remaining in school, having a post-doc and getting a job in industry. Not one of us currently has a tenure-track faculty position. Something must be very broken in the system for prospects to be this bleak for graduates of a top-five department.
So why doesn't the market change such that supply meets demand? Essentially, it's that the system runs on cheap graduate and postdoctoral labor. "Yet many academics are reluctant to rock the boat as long as they are rewarded with grants (which pay for cheap PhD students) and publications (produced by their cheap PhD students). So are universities, which often receive government subsidies to fill their PhD spots." In fact, faculty members who are reluctant to perpetuate this cycle are punished in grant review, writing in costs for a research scientist at $80,000 per year when others have the same work done by a postdoc at $40,000 per year.
So, how did we get here? Part of the issue has to be that more people are going to college than ever before and the university system does not properly scale to the demand. In the US in 1970, only 11% of people over the age of 25 had a bachelor's degree, but this number had climbed to 28% by 2009. So more graduate students, postdocs and adjuncts are being used to teach the courses to accommodate all of these new students. While some claim that it is just too expensive to have tenure-track faculty teaching all of these courses, one must also consider the recent trend towards massive salaries for university professors.
Actually, if anyone could explain university economics to me, I'd be grateful.
And where do we go from here? Personally, I love the suggestions made by William Deresiewicz in this fantastic article. Particularly, "The answer is to hire more professors: real ones, not academic lettuce-pickers."
Wednesday, May 4, 2011
(Just) soundbites
Touching article on the end of life and career of an ALS researcher who is succumbing to the disease of his own expertise.
A really great article on irrational affection for sports teams, written by someone who clearly understands that all human drama can be explained in terms of the 2004 Red Sox.
Speaking of sports, some insight into elite athletes who push beyond the limits of their bodies. On the less fatal side of things, dissociating oneself from current discomfort can be an effective strategy for top performance.
We have so much data! Can't we do something more interesting with it than get people to click on ads?
Over at the Statistics Forum, curious close replications are discussed.
A really great article on irrational affection for sports teams, written by someone who clearly understands that all human drama can be explained in terms of the 2004 Red Sox.
Speaking of sports, some insight into elite athletes who push beyond the limits of their bodies. On the less fatal side of things, dissociating oneself from current discomfort can be an effective strategy for top performance.
We have so much data! Can't we do something more interesting with it than get people to click on ads?
Over at the Statistics Forum, curious close replications are discussed.
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