Wednesday, September 26, 2012
Why texting while driving is a bad idea
Today I want to turn again to the issue of perception. Before I discuss the topic for today, I want you to watch this video. Then, below the fold I will discuss some of the interesting implications that this video has for our understanding of human perception.
Tuesday, September 25, 2012
Reality has a well-known liberal bias
Wishful Thinking is a fallacy in which on argues that something is true because she wants it to be true. As should be clear, this is a fallacy because the universe is generally indifferent to what we want. Reality is objective and wishing things worked differently is not going to make them happen. In my daily reading of the news I cam across this story on Salon.com about a website, UnSkewed Polls which claims to correct for liberal bias in all national polls. According to the author of this site, all national polls are skewed towards the democrats due to liberal bias among the pollsters. The author then claims to be able to correct for this bias, and when he does so, it appears that Romney is leading Obama by 7-10 points, a significant margin.
The basic "methodology" if we can call it that, is to assume that the votes of Republicans are under-counted, so the author simply reweights the polls so that, in his opinion, Republicans are no longer under-counted. For example, the author assumes that 34% of voters are Republicans. So, if a poll shows that only 24% of the respondents are Republicans, then the data must be skewed. So, the author reweights the data as if those 24% of respondents actually accounted for 34% of respondents. Basically he just gives more weight to the polling data of people identified as Republicans. Unsurprisingly, this reweighting seems to always lead to Republican dominance in the polling. Basically he is counting each Republican vote multiple times, which naturally leads to Republican dominance in the polling. If you don't believe that this is what the author is doing, you can read the details of this "methodology" here.
As should be obvious, this is a classic example of wishful thinking. The author doesn't like how reality is structured, so he just wishes up a new reality and assumes that to be correct. The problem, of course, is that the people who conduct the polling are really quite good at it, and very good at correcting for various biases. As Nate Silver of the NY Times notes:
The basic "methodology" if we can call it that, is to assume that the votes of Republicans are under-counted, so the author simply reweights the polls so that, in his opinion, Republicans are no longer under-counted. For example, the author assumes that 34% of voters are Republicans. So, if a poll shows that only 24% of the respondents are Republicans, then the data must be skewed. So, the author reweights the data as if those 24% of respondents actually accounted for 34% of respondents. Basically he just gives more weight to the polling data of people identified as Republicans. Unsurprisingly, this reweighting seems to always lead to Republican dominance in the polling. Basically he is counting each Republican vote multiple times, which naturally leads to Republican dominance in the polling. If you don't believe that this is what the author is doing, you can read the details of this "methodology" here.
As should be obvious, this is a classic example of wishful thinking. The author doesn't like how reality is structured, so he just wishes up a new reality and assumes that to be correct. The problem, of course, is that the people who conduct the polling are really quite good at it, and very good at correcting for various biases. As Nate Silver of the NY Times notes:
First, the polling by this time in the cycle has been reasonably good, especially when it comes to calling the winners and losers in the race. Of the 19 candidates who led in the polls at this stage since 1936, 18 won the popular vote (Thomas E. Dewey in 1948 is the exception), and 17 won the Electoral College (Al Gore lost it in 2000, along with Mr. Dewey).If the author of UnSkewed Polls was correct that polls have a statistically significant liberal bias, then why are they accurate predictors of the winner of the popular vote 94% of the time? If such liberal bias was infecting the polls, we wouldn't see them as accurate predictors of the winner so often. Thus, the only way the author of Unskewed Polls can object to polling data is by making up his own methodology that tells him what he wants to hear. As Stephen Colbert famously remarked concerning George W. Bush's falling approval ratings:
Now, I know there are some polls out there saying this man has a 32 percent approval rating. But guys like us, we don't pay attention to the polls. We know that polls are just a collection of statistics that reflect what people are thinking in reality. And reality has a well-known liberal bias ...
Monday, September 24, 2012
Big Pharma Hides the Truth
The science columnist, author, and academic Dr. Ben Goldacre, has just written a new book about the pharmaceutical industry, Bad Pharma: How Drug Companies Mislead Doctors and Harm Patients. In connection with the publication of this book, The Guardian has published an excerpt. In this excerpt, Goldacre discusses a number of fallacies regularly committed by the pharmaceutical companies in their efforts to get their drugs approved for use by various government regulatory agencies. We can see these fallacies clearly exemplified in Dr. Goldacre's discussion of the anti-depressant reboxetine.
Friday, September 21, 2012
Two Dimensional Eyes, Three Dimensional World
Having taken a break from perception to discuss some of the latest political idiocy, I want to conclude my posting this week with a little more discussion of perception. My comments here are taken from the excellent, interactive website on the brain published by McGill University. They have an excellent section on perception which discusses vision from the molecular level all the way to the social.
One facet of the site that really caught my attention was the discussion one of the major sources of visual ambiguity, which is the fact that our visual system, specifically our retina, is only capable of taking in information about a two-dimensional world, yet our brain is able to create the visual impression of living in a three-dimensional world. Let me quote the explanation from the website:
This ties in nicely with the waterfall illusion I discussed earlier. The key there was that the impression of an impossible object was created through perspective. The artist was able to create what appeared to be an impossible object in the real world by exploiting the fact that our retinas can only receive information two-dimensionally. Thus, when we observe these different objects from the correct perspective, they appear to be one unified, impossible object.
A further illustration can be found on this interactive webpage.
One facet of the site that really caught my attention was the discussion one of the major sources of visual ambiguity, which is the fact that our visual system, specifically our retina, is only capable of taking in information about a two-dimensional world, yet our brain is able to create the visual impression of living in a three-dimensional world. Let me quote the explanation from the website:
One important source of ambiguity for the visual system is that the world is three-dimensional, but the images that it projects onto your retina are two-dimensional. Hence differing objects, depending on their distance and orientation, may occupy the same amount of surface area on your retina. Your brain therefore becomes confused, and tries to use other indicators to clarify the situation. Two such indicators are your own past experience with the object in question and the experience of the human species, which is encoded in your genes.They even include a helpful picture which shows how three different objects could produce the same image on our retinas:
This ties in nicely with the waterfall illusion I discussed earlier. The key there was that the impression of an impossible object was created through perspective. The artist was able to create what appeared to be an impossible object in the real world by exploiting the fact that our retinas can only receive information two-dimensionally. Thus, when we observe these different objects from the correct perspective, they appear to be one unified, impossible object.
A further illustration can be found on this interactive webpage.
Thursday, September 20, 2012
They're coming to cut your throat! And they have Korans!
On the September 18th edition of the Fox News show Your World with Neil Cavuto filmmaker Michael Lynch was interviewed about his new movie about illegal immigration. In the course of this interview Lynch commits a number of fallacies:
The most obvious fallacy is the use of Scare Tactics. Note that the video start with a news report about a prison break on the Mexican side of the US-Mexico border. Cavuto and Lynch then imply that all 130 of these prisoners are extremely violent and that they are making a beeline for the US. Note as well that we are told nothing about the prisoners. For all we know they may all have committed the Mexican equivalent of white collar crimes and are non-violent offenders. Even assuming that they are violent offenders, there is no evidence that every single one of them (or any of them) will head to the US. For all we know these escaped prisoners may make an effort to reunite with their families in Mexico. Furthermore, it is even possible that some of the prisoners are US citizens. We have no idea, the report gives us no information, but tries to scare us and make us afraid of all the murderous violent immigrants who are heading are way.
Lynch then almost immediately invokes 9-11, attempting to draw a link between illegal immigrants snaking across the US-Mexico border and terrorism. At this point it is worth noting that none of the 9-11 hijackers entered the US this way. All of them exploited legal means of entry. This is clearly an example of a False Analogy, as it is wildly inappropriate to invoke 9-11 when discussing the status of the US-Mexico border. Lynch doubles-down on this false analogy when he claims that someone is finding Korans and prayer rugs in the middle of the desert. I have no idea if this claim is true, but I find it highly suspicious. If in fact Muslim terrorists were sneaking across the US-Mexico border, I doubt that they would be scattering their holy book across the middle of nowhere.
From this Lynch then employs another Scare Tactic, claiming that not everyone is coming to the US to cut your lawn, some of them are coming to cut your throat. Again, no evidence or statistics are provided for this claim, Lynch just asserts it with the obvious intention of scaring the Fox News viewers into buying his movie.
We then see a nice example of Inconsistency when Cavuto asks Lynch why immigrants are coming to the US and Lynch responds, "Jobs," thereby directly contradicting his earlier assertion that at least some of the immigrants were coming to commit murder.
Lynch then transitions to an Appeal to Authority citing a positive review from some Fox News celebrity as evidence that his movie is worthwhile and important.
Finally he concludes with the classic huckster's pitch claiming that he has secret information that "They" (whoever "they" are) don't want you to see. In this connection Lynch implies that there is some large-scale conspiracy devoted to suppressing the truths that he, as a normal, hard-working American, is trying to expose. In general, when someone cites a conspiracy as the reason why no one will show their movie, we need to seriously consider the possibility that no one will distribute or screen the film because it sucks, not because it reveals some uncomfortable truth.
h/t to Media Matters
The most obvious fallacy is the use of Scare Tactics. Note that the video start with a news report about a prison break on the Mexican side of the US-Mexico border. Cavuto and Lynch then imply that all 130 of these prisoners are extremely violent and that they are making a beeline for the US. Note as well that we are told nothing about the prisoners. For all we know they may all have committed the Mexican equivalent of white collar crimes and are non-violent offenders. Even assuming that they are violent offenders, there is no evidence that every single one of them (or any of them) will head to the US. For all we know these escaped prisoners may make an effort to reunite with their families in Mexico. Furthermore, it is even possible that some of the prisoners are US citizens. We have no idea, the report gives us no information, but tries to scare us and make us afraid of all the murderous violent immigrants who are heading are way.
Lynch then almost immediately invokes 9-11, attempting to draw a link between illegal immigrants snaking across the US-Mexico border and terrorism. At this point it is worth noting that none of the 9-11 hijackers entered the US this way. All of them exploited legal means of entry. This is clearly an example of a False Analogy, as it is wildly inappropriate to invoke 9-11 when discussing the status of the US-Mexico border. Lynch doubles-down on this false analogy when he claims that someone is finding Korans and prayer rugs in the middle of the desert. I have no idea if this claim is true, but I find it highly suspicious. If in fact Muslim terrorists were sneaking across the US-Mexico border, I doubt that they would be scattering their holy book across the middle of nowhere.
From this Lynch then employs another Scare Tactic, claiming that not everyone is coming to the US to cut your lawn, some of them are coming to cut your throat. Again, no evidence or statistics are provided for this claim, Lynch just asserts it with the obvious intention of scaring the Fox News viewers into buying his movie.
We then see a nice example of Inconsistency when Cavuto asks Lynch why immigrants are coming to the US and Lynch responds, "Jobs," thereby directly contradicting his earlier assertion that at least some of the immigrants were coming to commit murder.
Lynch then transitions to an Appeal to Authority citing a positive review from some Fox News celebrity as evidence that his movie is worthwhile and important.
Finally he concludes with the classic huckster's pitch claiming that he has secret information that "They" (whoever "they" are) don't want you to see. In this connection Lynch implies that there is some large-scale conspiracy devoted to suppressing the truths that he, as a normal, hard-working American, is trying to expose. In general, when someone cites a conspiracy as the reason why no one will show their movie, we need to seriously consider the possibility that no one will distribute or screen the film because it sucks, not because it reveals some uncomfortable truth.
h/t to Media Matters
Wednesday, September 19, 2012
Don't go chasing waterfalls. You just run around in circles.
Most people are familiar with this very famous optical illusion designed by M.C. Escher:
This illusion works because Escher is exploiting the way our brains perceive perspective in order to create a visual paradox. Most artists use these rules of perspective to create realistic three dimensional images on a two-dimensional piece of paper, but Escher is manipulating these rules to create this famous illusion.
Despite the fact that this illusion has its origins in the exploitation of rules of perspective in drawing, it turns out that one can actually build such an object in the real world! A video is below the jump.
This illusion works because Escher is exploiting the way our brains perceive perspective in order to create a visual paradox. Most artists use these rules of perspective to create realistic three dimensional images on a two-dimensional piece of paper, but Escher is manipulating these rules to create this famous illusion.
Despite the fact that this illusion has its origins in the exploitation of rules of perspective in drawing, it turns out that one can actually build such an object in the real world! A video is below the jump.
Tuesday, September 18, 2012
In the eye of the beholder
One of the coolest things about optical illusions is what they reveal about how human perception works. One of my favorite optical illusions in this respect is the Checkershadow illusion discovered and analyzed by Edward H. Adelson in 1995. Here is the illusion:
The trick here is to look at squares A and B. B obviously appears to be a much lighter shade of gray than A. However, if we isolate the two squares from the larger context, we can actually see that they are the same shade of gray. This gif below the jump illustrates that point:
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