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Tuesday, March 31, 2009

I was not expecting that...

I'm busy fighting the suicidal urges of my robots, so in the meantime, here is an incredibly odd video I rather enjoyed:

I mean, who saw that coming? And I thought having wild turkeys wake me up by pecking at their reflection in our basement door a few summers ago was a fun story to tell... but it doesn't hold a candle to this.

Sunday, March 29, 2009

"It's Alive"

I know I've been mentioning a plan to do some posts about my fourth year project for a while now but have yet to actually put something up. Well, this still won't be anything substantive, but I did want to make a guardedly excited post to commemorate the "It's alive" moment my simulated robots had tonight when I finally integrated their control network with the main environment function (effectively turning their brains on). There are clearly still some bugs to work out since, so far, five of the seven simulations I've run have seen the single robot awkwardly wobble toward the wall before finally running into it and 'dying'. I would upload some videos if it weren't so sadly pathetic (and I still haven't gotten around to learning how to use the software I downloaded the other day to turn a series of jpeg images into a video). Anyway, over the next couple weeks I need to finalize my work on the project and write my final report on it (a mini dissertation), so during that time I'm unlikely to be feeling up to spending even more time on the bloody thing writing about it here (other than the occasional "I did it!" posts that will hopefully occur). However, once all that is complete, I should be up to the task of finally explaining just with what exactly I have been whittling away the hours for the past two semesters. At that point, too, I should have some results other than some twitching leading up to ignominious suicide, so wish me luck.

A Return of Quotations

It has been some time since I regaled you with snippets of thought from people more consequential than I. It is time to remedy the situation.

"Women love scallywags, but some marry them and then try to make them wear a blazer." - David Bailey, English photographer, 1938-

"Money, it turned out, was exactly like sex, you thought of nothing else if you didn't have it and thought of other things if you did." - James Baldwin, American novelist, 1924-87

"It is unfortunate, considering that enthusiasm moves the world, that so few enthusiasts can be trusted to speak the truth." - Arthur James Balfour, British Conservative statesman and Prime Minister, 1848 - 1930

"If I'm not a genius, I'm done for." - Honore de Balzac, French novelist, 1799-1850

After reading the remark by David Bailey, I wonder if any of my readers can guess who it makes me think of. As a hint, it is a character in a television show I have referenced before.

Wednesday, March 25, 2009

"Kids say the darndest things"

Monday morning I had my first Brain Day experience in which a friend of mine from my neuroscience lab course last semester and I went into a classroom of children in grades 3 and 4 and taught them about the brain (primarily with the intent on brain and spinal cord injury prevention, although we had a lot of extra 'just because it is interesting' material in there too). It was an interesting experience. While I will wait until after my second Brain Day presentation to write about the events themselves, there was one cute anecdote I wanted to share now while I procrastinate studying for my pair of midterms this evening.

When I was living in Pennsylvania, my German teacher in grade 8 had an amazing collection of ties. As far as anyone could tell, he wore a tie every day and did not ever repeat a tie over the course of the school year. After such an impressive display of tie wearing, sporting a tie and teaching young children now go together in my head. To that end, I informed my presentation partner that I intended to wear a tie for our presentation (I have one my mom bought me a few years ago that is covered in mathematics equations and simple diagrams), so she decided she had better dress up a little too. To that end, I showed up in a dress shirt and tie, and she showed up in nice clothes and high heels. As we neared recess, I was talking to the class about the auditory system when one of the little girls in the class raised her hand and called my partner over. Instead of asking a question about the brain, however, she informed my partner that she and I must be married, since I was wearing a tie and she was wearing high heels.

While I presume my partner explained the difference between a married couple and academic peers (or something to that effect), I enjoy the story because I find it interesting how often young children make these seemingly bizarre leaps in logic. What is even more interesting is quite often, if asked, the children can give quite a coherent, if misguided, outline of the logical steps they took to reach the given conclusion. I never got the chance to ask this little girl how she arrived at the conclusion that tie and high heels meant marriage, so I remain curious.

Tuesday, March 24, 2009

Visceral Emotions

I have had a request to write about the physiological basis for emotional reactions to be felt in other parts of the body, namely the sensation of heartache and gut feelings, both of which fall under the category of visceral emotions (perhaps not officially, but within my own individual vernacular they at least do). There are several possible reasons for such sensations, so what I am going to discuss in this post is a great deal of conjecture and, though I expect it is fairly reasonable, might of course be refuted by careful scientific study.

There are three main aspects of our physiology that I think best explain the sensation of visceral emotions. The first is that our body is essentially formed segmentally (an evolutionary throwback to the days of worms) with a series of dermatomes (I've linked to the Wikipedia article on them for those that don't know what I'm talking about). While dermatomes are fairly well defined (though with some overlap) on the surface of our skin, things get somewhat less organized when it comes to our insides. Organs might form embryologically with one segment of skin but then get pushed and shifted around to end up somewhere else. Combined with the fact that many of our somatic sensations are not nearly as well localized as we sometimes assume they are (if you have ever done the test where, while blindfolded or looking away, someone simultaneously pokes you on the back or leg with a pair of pointy sticks separated by only a few centimetres you might know what I mean. It is very difficult (provided the poke comes simultaneously) to tell whether you have been poked in one spot or two), this can sometimes lead to a misallocation of sensation. One common example of this (at least for men) is the horrifying sensation in the pit of one's stomach after a blow to the testacles. Also, while I've never experienced them myself, other examples of misleadingly localized visceral pain include appendicitis and a hernia. Even heartburn is a misallocation of indigestion to pain in the heart.

The second major aspect of our physiology which leads to visceral sensation of emotions is the widespread autonomic responses we experience corresponding to shifts in our mental state. As we enter states of alertness, our sympathetic responses tend to be recruited and our heart-rate increases. The sympathetic nervous system is most famously known for its role as the 'fight or flight' response system, but it is engaged by other stimuli as well. Thus, while you have no intention of fighting a pretty girl or handsome guy whom you would like to go on a date with, the presence of your crush still elevates one's alertness and results in many of the same responses that result from stress and fear. I'm not actually sure the physiological reason, but acute action of the sympathetic nervous system can sometimes lead to vomiting and nausea (if anyone has ever been in an exam room in which a test taker was so nervous he lost his lunch, you have an idea of what I am talking about), which might help explain the (much more pleasant but similar) sensation of 'butterflies in the stomach'. A fairly cute psychology study was done a number of years ago in which an attractive lady stopped men for a survey in two different situations. In the first, she waited on a foot-bridge over a rather severe drop, and in the second she simply stopped men on the street. Part of the survey asked for takers to follow-up with a phone call to the researcher. Significantly more of the men who encountered the attractive lady over the gorge made the follow-up call. This was interpreted (debatably, of course, like a lot of psychology research) to mean that the men who encountered the lady in a dangerous situation found her more enticing due to a conflation of their physiological response to the fear (quickened heart and elevated alertness) with a similar response to an attractive member of the opposite sex. While I don't think the study was in any way conclusive, I bring it up now because I do think it provides some supporting evidence for the fact that there is not a unique set of physiological responses to every emotion. Rather, there is a messy and often confused interplay.

The third aspect of our physiology involves the setup of our reward pathways and their strong connection to our viscera. After all, when you think of people as survival and propagating machines, obtaining and consuming sustenance and having sex are pretty much the two main functions (we are, of course, slightly more complicated than that, but those are integral aspects of our species). One of the favourite "brain facts" espoused by clever people who sometimes like to repeat relatively inane facts in lieu of conversation is that eating chocolate provides some of the same pleasurable sensations as sex. While true, the statement is still rather misleading because virtually all food does (particularly when one is excessively hungry), since food and sex are both largely driven by the reward pathways of the limbic system. Chocolate just happens to be an especially rewarding food, and thus sounds better than, say, broccoli and cheese. Chocolate also seems to be a favourite with women, and thus using chocolate in the sentence has a greater chance of garnering a wry smile and snide response, "Oh, I think it's better," from a lady in the group as she gives her boyfriend obviously coy eyes, at which point everyone gets a good chuckle (except, perhaps, for the poor fellow with the slighted sexual prowess).

Taking these three physiological aspects together, I think we may now make a reasonable conjecture as to the nature of both heartache and gut feelings. I will start with heartache, which I am interpreting for the purposes of this post to mean a deep ache felt in the lower chest following a break-up, loss of a loved one, or some other sense of emotional loss. This sensation, I believe, mainly combines aspects of the first two physiological facts discussed. Emotional loss can be deeply distressing, thereby vastly increasing a person's stress levels and forcing a powerful response from the sympathetic nervous system. Unlike in the case of the attractive lady on the bridge discussed above, there is no positive stimulus upon which one can distract and project their feelings, and thus they are interpreted as wholly unpleasant. With an increase in heart rate and mild nausea from increased stress, I surmise that the brain interprets the sensation as an ache centred upon the heart.

A gut feeling, on the other hand, seems to involve the third aspect more than the other two. For me, at least, gut feelings are not particularly localized in the gut, but are rather a sensation that something feels like the right solution from the core of one's being. One thing which many people do not realise about the brain is that the emotional parts of the brain (which tend to be concentrated around the limbic system) actually do quite a bit of information processing and decision making (it is not all rational thought processing and planning from our frontal cortex). This is actually one of the favourite topics discussed by Jonah Lehrer, particularly since it is the subject of his latest book. I plan to write a post about it myself going into more detail, but I hope the aspects of our physiology I discussed in this post can at least give one a general idea for a possible physiological basis for gut feelings and viscerally felt emotions in general.

Sunday, March 22, 2009

Tomorrow and Friday are Brain Days

Tomorrow and this coming Friday I am going with a friend from some of my neuroscience courses as a Brain Day volunteer to teach some elementary school kids about the brain. The primary emphasis of the event is to teach about brain and spinal cord injury prevention, but we actually cover quite a bit more than that. I don't know if this is just an Ontario thing or maybe my hometown in BC was just too small (and obviously lacked university students studying the brain), but I don't remember this when I was in school. Anyway, I am surprisingly nervous about doing this, mainly because I sometimes get flustered by young children. I am a strong believer in not talking down to children, but at the same time I'm not sure how that will translate into a classroom setting. Well, I just wanted to put up a quick note. I should be doing some lesson plan preparation and then I have to go meet my partner and practice. I will try to put up a post to mention how this goes. Hopefully the young children will not be too scary.

Wednesday, March 18, 2009

The tragedy that is our current government

As many of my readers are likely aware, the current Canadian Minister of Science, Gary Goodyear, recently horrified many by responding to a question of his belief in evolution (granted, a poorly worded question) with what is possibly the worst and most unsettling dodge possible:
I'm not going to answer that question. I am a Christian, and I don't think anybody asking a question about my religion is appropriate.
That response is highly troubling because the Minister of Science should not think a question about evolution is a question about religion. Apart from the troublesomely loaded word 'believe', the question had no religious content whatsoever, and it was Mr. Goodyear himself who invoked the religious aspect by conflating a 'belief' in evolution with questioning his Christianity. This has been well and thoroughly discussed, however, so I won't elaborate on this part of the story... what horrifies me is his attempt at a clarifying response:
We are evolving every year, every decade. That's a fact, whether it is to the intensity of the sun, whether it is to, as a chiropractor, walking on cement versus anything else, whether it is running shoes or high heels, of course we are evolving to our environment. But that's not relevant and that is why I refused to answer the question. The interview was about our science and tech strategy, which is strong.
His response continues to show only a shaky grasp at best of what evolution actually means. Reading further into this fellow's views, he also seems to think it is proper to solely undertake scientific research with a clear practical goal in place. This man is a terrible candidate for a Minister of Science.

From whence came the word "propulgate"

Just a quick note: if my memory serves me correctly, no one guessed and I never revealed the source of the titular reference to the fake word "propulgate" in my previous post on ignorance. The term comes from the enjoyable political show The West Wing, in the episode "Disaster Relief". The vice president Bob Russell, who is not the sharpest member of the political cabinet, uses the term in a meeting to the chagrin of those on his side and confusion of those to whom he is speaking.

Note: I have also started labelling posts with titular references with the tag "Reference Game". While I have not gone back and retroactively labelled all those posts that came before, perhaps I will get around to it at some point. In the future, it should make things a little more organized.

Puzzle Number Two

Since the last puzzle was (rightly) pointed out to be relatively straightforward (though tedious), I thought I would go with a fairly challenging problem for this one. This is actually one of my favourite problems from the probability course I took last year. I should warn you that it is a fairly challenging problem, though, unlike most puzzles, doesn't really take any tricks or subtleties of the language. Instead, solving it will require some skill with calculus and probability theory as well as some relatively straightforward reasoning.

So, without further rambling, the problem is as follows:

You have a floor made up of parallel boards of width D (like a typical hardwood floor) and a uniform metal rod of length L, where L < D. Assuming that when one drops the rod it will land with uniform probability in any position and orientation on one of the floorboards (and, obviously, position is independent from orientation), is it possible to derive an empirical estimate for π through repeatedly dropping the rod and counting the number of intersections with cracks between floorboards? If so, how?

Tuesday, March 17, 2009

Applications, Deadlines, and My Emotional Well-Being

Some may have noticed (especially those who have made recent topic requests) a slowing down of activity around here in the last week or so. I have been having a rough time getting around to attending this blog as the weight of the impending future bears down upon me. I underestimated the time involved not just in finding places to apply to and doing the applications (mostly because I find the task extraordinarily unpleasant, as I have so eloquently mentioned before), but also in securing funding (I should have seen this coming, seeing as how money is involved, but silly me just thought financial packages came as part of the graduate school acceptance thing). This is especially true for applications to Europe, where I am seriously considering due to their extensive work in computational neuroscience and artificial intelligence (particularly in Germany, but EPFL in Switzerland and Edinburgh both have very good schools for robotics). Anyway, as I decide my future, I have found it difficult to motivate paying attention to the blog. I apologize. I am working hard on forcing myself to worry less and function more, but it is a difficult task. New content is in the process of being produced, but my posting frequency might slow down for the next couple of weeks.

Friday, March 13, 2009

A Course I'd Like to Take

The other day while I was walking to school my mind was wandering between the uncertain future and reflections on my undergraduate education. As I find myself more and more drawn toward an interest in robotics and computational models of intelligence with my neuroscience background serving in a more supplementary role, I was thinking about how the neuroscience courses I have taken have served my educational development. At a university there tends to be a few aspects of a subject which are more popular with the majority of professors, and this tends to be reflected in the available courses. Here at the University of Toronto (U of T), there are approximately three ways to study the brain: behavioural psychology, microbiology and genetics, and systems neurophysiology. Of those three, I find I prefer the systems approach despite the fact that it tends to be less research-oriented than the microbiology approach (as one may guess, behavioural psychology I have the least time for). The reason I prefer the systems approach is that it tends to take a more global look at the brain and understand how it performs (though it tends to come at this from a more clinical diagnostic perspective than a theoretical modeling one), while the microbiology approach I find frustrating in its excessive detail. Thus, while the microbiology approach tends to be more research oriented, it is in avenues of research which I find to themselves be far more clinically oriented (not that clinically oriented biomedical research is a bad thing - in fact, I am expecting it at some point to likely save my life. It is simply I find the research itself mostly tedious and uninteresting).

I have gotten myself off on a tangent, however. What I intended to do was outline a course which does not exist (as far as I know) but which I would have found fascinating to take. As I mentioned, I find the systems approach to be the most appealing, but most of that approach is done at U of T with a clinical mind. When non-human animals are discussed, it is almost always in the case of a specific study with a mind to extrapolate the information to that which is applicable to understanding and diagnosing deficits in the human brain (despite the fact that we understand many of the widely used model organisms' nervous systems far better than our own). What I would find fascinating would be a course on comparative neurophysiology. For example, our cerebral cortex is, as I understand it, a mammalian novelty (and this is where most of our higher brain functions are found). Despite the avian lack of a neocortex, many birds have an odd similarity to primates in terms of cognitive function (with many extremely visual and social species). A course that examined in detail how the visual system, for example, of predatory birds compared to that of primates might be extremely illuminating in understanding visual processing techniques. Likewise, there are many non-humans which show remarkable manual dexterity and spatial reasoning (elephants with their trunks and confounding cephalopods come to mind). While I would guess that the elephant motor cortex would likely closely resemble our own due to our shared mammality, looking at the motor control mechanisms of invertebrates as dexterous as an octopus could be quite fascinating. So, if any professors happen to be reading this and know someone who might be interested in setting up a course like that, I think it would be quite worthwhile ( I just hope there are other students out there who would find the same thing if someone goes through the trouble of setting it up).

Note: I made the word mammality up. Is there an actual word that means what I was trying to say? Mammalianity?

Tuesday, March 10, 2009

Naughty humour with the cranial nerves

Warning: This post has some racy humour in it. Reader beware.

Wednesday I have my first (and hopefully only) university bellringer exam. This is a daunting examination technique popular in medicine and anatomy in which students are sent into a room around which multiple stations have been set up. Each station has a bit of tissue (either preserved or fresh) or some sort of medical image (an fMRI slide or some other such image) that has been marked in some way (a toothpick sticking out of the tissue or an arrow sticker on the slide) and then the student is asked to either simply name the structure or answer some sort of clinical question about the structure (for example, a blood clot in what artery would lead to loss of function in this structure?). One of the things which I have to learn for this exam is my old nemesis - the cranial nerves. For some reason, remembering the names and locations of those twelve stupid nerve fibres coming out of the brainstem eludes my memory more than any other part of neuroanatomy. I am clearly not the only person who has this problem, as there are dozens of mnemonic devices designed to help people remember the cranial nerves. These range from the rather tame, "On old Olympus' towering top a finely vested German vaults and hops" to the decidedly disturbing, "Oh, oh, oh, to touch and feel virgin girls' vaginas and hymen". Of course, while the latter mnemonic might be more memorable simply due to its shocking lewdity, it does run its own special risks as one girl in my neuroanatomy class related in our last lab. You see, the cranial nerve corresponding to the word vagina is the tenth cranial nerve called the vagus nerve. It thus shares the first three letters with its mnemonic counterpart, dramatically increasing one's risk when writing quickly on a test of starting with the 'vag' part and doing a mental flip to finish off the answer with an 'ina' rather than an 'us'. While the girl relating this story realised her mistake and rectified it, the moral of the story is clear. Filthy humour may be a wonderful memory aid, but you use it at your own risk.

Note: For the record, the cranial nerves are:
I. Olfactory
II. Optic
III. Occulomotor
IV. Trochlear
V. Trigeminal
VI. Abducens
VII. Facial
VIII. Vestibulocochlear
IX. Glossopharyngeal
X. Vagus
XI. Accessory
XII. Hypoglossal

Sunday, March 8, 2009

Puzzle One Solution

It took me longer than I had planned to get around to posting this solution, but here it is. If you recall, puzzle number one was concerned with finding the starting pair of numbers from 0 to 9 which provided the most iterations before reaching zero of taking the new number pair from the digits of the product of the previous pair. While I invented this puzzle as an aid to falling asleep (in which case brute force mental computation was actually the desired outcome), I was curious to see if anyone would come up with an elegant solution based on numerical logic rather than simply trying every single combination. While Scott (whose blog I just discovered is not on my "Places of Interest" list... I could have sworn it was!) mentioned he did spend some time mentally contemplating the solution, both he and Wisefly ended up doing the same thing I did to confirm the answer - write a short computer program that simply tried every starting combination and looped through the iterations. Wisefly used Excel, Scott used python, and I used MatLab. If anyone is curious about the specific code used to find the solution, either leave a comment or send me an email and I can send you my .m file. Roughly, the pseudocode is as follows:
maxCount = 0, maxStart = 0
for i = 1 to 99
count = 1, x = floor(i/10), y = mod(i,10)
while(x*y > 0)
count++, iter = x*y
x = floor(iter/10), y = mod(iter,10)
end while
if(count > maxCount)
maxCount = count, maxStart = i
end if
end for

Of course, for some reason I cannot get white space to stick around even within block-quotes, so my pseudocode comes out looking like crap. Please forgive its lack of spacing. Also, if you are not used to my pseudocode (which is entirely possible), floor yields the rounded down integer value of the value passed to it (for example, floor(5/3) = 1) and mod is the modulus (or remainder) of the first number by the second (for example, mod(10,4) = 2).

Anyway, running the program yields the correct answer of 77 (or x = 7, y = 7) as your starting value. 7*7 = 49, 4*9 = 36, 3*6 = 18, 1*8 = 08, 0*8 = 0. Thus, there are five iterations before the value becomes 0. As was pointed out to me, this was a relatively straightforward puzzle when one wrote a computer program to solve it (and even without the computer program it was feasible to solve by some relatively simple number crunching). Wisefly suggested modifying the puzzle such that instead of being in base 10 (ie. taking starting integers from 0 to 9), it would be interesting to see what the results were for a base n system, where n is anything greater than 2 (taking a base 2 system yields the trivially obvious solution of both x = 1 and y = 1, as the three other starting choices go to 0 immediately). This is relatively easy to do by just replacing the values of 10 in the above code by n and running the for loop from i = 1 to n*n-1. One can then look at the results of this and see if some sort of pattern emerges which would allow one to pick the appropriate best starting digits for a given base n without having to resort to brute force methods. I have completed the modifications to my own program and run it for values from 2 to 6 without spotting any sort of discernable pattern. I do plan on doing some actual work this afternoon, so I have tabled this for now but might explore it in the future. If anyone decides to explore this themselves and comes up with some interesting ideas, feel free to send me your results.

Note: I made the mistake this time of not keeping an accessible list of those who solved the puzzle and sent me solutions. While I think it was just Wisefly and Scott, if my memory has failed me and I forgot someone, please send me an email or leave a disgruntled comment, and I will make the appropriate changes to this post.

Edit: Thanks to Paul's helpful comment, my pseudocode looks a little more readable now.

Wednesday, March 4, 2009

A quick shot of humour at the expense of Conservapedia

As some of you may recall, I have previously discussed that rancid cesspool of blinkered insanity known as Conservapedia, so I thought it might be interesting to point out this enjoyable post in which the following quotation from the article on Earth's moon is brought to light:
Atheistic theories of the origin of the Moon, widely taught for decades despite lacking the falsifiability requirement of science (see Philosophy of science), have been proven false.
While Joshua Zelinsky discusses that quotation in more detail in his post, I just enjoy marvelling at the beautifully inane lack of logic.

A brief delay in posts

Despite the fact that I thought this would not be too busy a week, I have been earnestly working on finishing off graduate school applications and making progress on my fourth year project. That has resulted in neglect of this blog, which I thought might deserve some acknowledgement. Within the next two days I plan to post the solution to puzzle number 1 followed by the next puzzle. I have also been trying to figure out how to create a video out of the graphical display generated by my project to upload, but there is no guarantee that I will figure that out by the end of the week (getting the project actually working has a somewhat higher priority). However, even if I cannot upload a video, I should have a post discussing the project in general by the weekend (it's a neat one, with simulated robots).

Also, for those who have subscribed to this blog using an RSS service like Google Reader, you may have noticed a continued lack of advertisements. Clearly, something is wrong with my utilization of AdSense. It's unfortunate, because while I don't actually want to inundate you with ads, I was looking forward to reading the statistics generated by AdSense automatically on the number of people who subscribe to my site. Oh well, maybe I will get the problem figured out in the near future.

Sunday, March 1, 2009

One more administrative thing

Annoyed that another batch of images got slightly cut off in the display, I have fiddled around the with display parameters for the blog. Hopefully the changes should make it look more readable, but if they mess anything up for anyone or frightfully impinge upon your aesthetic sense, please let me know.

Top-down Processing in Visual Perception Part III: Artificial Edges

This was supposed to be the concluding chapter in my series on top-down visual processing started in part one and continued in part two, but it got quite a bit longer than I expected and will thus be expanded in an upcoming fourth part. In the first installment I introduced the concept of top-down and bottom-up processing and gave a low-level example of top-down processing in the Necker Cube. In the second part I discussed faces in the context both of anthropomorphizing objects through the visualization of faces as well as a preponderance of optical illusions involving faces.

In this installment I am going to discuss another artifact of top-down visual processing which I am going to call artificial edges (I'm not actually sure if there is a better or more technical term for it, so if anyone knows of one, feel free to let me know). I find this phenomenon interesting from both a physiological aspect (in terms of providing evidence for top-down processing) as well as a machine vision aspect (in terms of duplicating our object recognition abilities). The basic idea is that our brain is fairly good at joining edges which belong to the same object but which have been in some manner obscured (either through occlusion, camouflage, or illumination problems). What is interesting, however, is that our visual processing system is so good at this that we can actually create edges and object boundaries that are not there. Two classic examples of this are shown in figures 1 and 2.
Figure 1

Figure 2

There is not actually a white square in figure 1, but the pieces removed from the black circles give the illusion of a white shape occluding them. Our mind then fills in the boundaries of the square to separate it from the white background to the point where we are able to discern boundary lines that are not actually there (of course, those lines disappear when one focuses on them since there isn't actually a change in hue). Figure 2 shows a somewhat more complicated version of the same phenomenon in which the image of a dalmatian is hidden within the scattered ink blots. The artificial edges created in these images are a consequence of our ability to group objects together and differentiate foreground from background. Part of our ability to do this rests in our expectations of what objects are most likely to appear in an image as well as our expectation of how such objects might be arranged. If figure 2 were shown to an individual who had never seen a dog (or even a dalmatian or similarly coloured dog), he would most likely have a very difficult (if not impossible) time spotting it.

That said, I am going to make a brief digression and point out one of the things that makes psychology such an annoying subject - differences in individual processing. Just as some people mentioned they had a difficult time spotting the old lady in the previous part, my girlfriend told me she does not see four circles occluded by a white square in the first image, but rather she sees four Pac-men biting a square. At the least the square is still there so she doesn't completely spoil my premise.

This ability to group contours and blobs together into expected objects is a massive advantage when it comes to image understanding, and it is one of the biggest problems in machine vision. Outside of tightly controlled circumstances, object contours rarely display consistent properties. This is hard for people to even spot, because our mind automatically accentuates valid contours and minimizes invalid contours as shading and texture.

Figure 3

To demonstrate this, I have included a picture I pulled off the internet of a chrome stapler (figure 3). As one can see, there are plenty of strong and weak edges in this image (when I speak of the strength of an edge, I mean roughly the rate at which pixel intensity changes. For a more thorough explanation, see the Wikipedia article). People have no difficulty picking out the stapler in this image and could easily outline the object if one were to ask, despite the fact that this is a monochromatic image and several of the boundary edges are much weaker than internal edges caused by shadow and geometric variations in the object's surface. For example, if you look at the two rearmost edges of the stapler, you can see that the posterior edge is virtually nonexistent while the lateral edge starts fairly strong near the bulb at the front of the stapler but fades as one moves toward the posterior. Our minds have no problem mentally accentuating that lateral edge along its entire length, however, and recognizing that it is a continuous edge despite its vast variation in edge strength. If you looks at the opposite side, however, you see a continuous dark band that extends the length of the stapler, forming two powerful edges. Neither of these strong edges actually depicts one of the object's boundaries, rather they are an artifact of the object's geometry, the view angle, and lighting. Thus, even a computer system whose sole purpose is to determine if one has a picture of a stapler or not would have a great deal of difficulty with that task without some pretty hefty processing on top of the edge detection (even then it would highly unlikely to be as reliable as a person, and we can recognize far more objects than just staplers) or some ability to constrain the view angle, lighting, and object variation. A great deal of these concepts are actually discussed in Gestalt psychology (if you follow the link to the Wikipedia article, you will see some familar images too. It looks like I could have just acquired links from there rather than searching randomly through the internet if I had looked at Wikipedia earlier).

I had planned on speaking about the ramifications of what I have discussed, but I have already been working on this post on and off for several weeks and it is starting to get cumbersome in length. I will therefore be expanding this series into a fourth post to be published in the not too distant future.

Continue reading in Part IV: Ramifications.

Another minor change

For those who actually show up here to read my posts, this won't affect you at all. However, for those that subscribe to feeds, I decided I would try following Google's advice and add 'AdSense for Feeds' to my site. That means that (hopefully unobtrusive) advertisements should start showing up at the bottom of substantive posts (I set a minimum word length, so you shouldn't be getting them on minor posts like this one). If it is distracting or upsetting, though, please let me know and I can see about removing it.

Follow-up Discussion

In my most recent post, I discussed both religion and suicide bombings. Both are subjects on which many people have quite strong opinions, so there were some responses to my post which I thought warranted some expansion. First and foremost is my discussion with Cornucrapia (conducted behind the internet's version of closed doors - a private chat. Therefore, if I make any mistakes in representing what he said, I apologize and hope he will set me straight). He made several points, the first of which was that he did not think my conclusion was as different from the article's as it appeared that I thought it was. Thus, I believe it is worth trying to more clearly elucidate just what conclusions I understood the article to have, and what my interpretation of the data entailed given my understanding and outlook on religion.

As Cornucrapia understood the article, it was saying that devotion to a religious institution is more indicative of suicide bombings than devotion to any particular god. In essence, I agree with that statement, but I interpreted the article more as saying that attendance and integration with a religious community was more indicative of suicide bombings than fervour of religious belief. Essentially, that is the same thing, just with a different emphasis. The way I read the article it seemed to be focusing on the community aspect irrespective of the beliefs held by the religion, whereas I thought that was an erroneous conclusion. To me, the dangers inherent in devotion to a religious community rest in the genuflection shown to those in charge of the community regardless of what they say or ask. As I tried to relate through my rambling discussion, in the vast majority of circumstances suicide bombings are a matter of manipulation, and religious organizations seem to be perfectly suited for recruitment into behavioural manipulation. Though I might have intellectual quibbles with personal spiritual beliefs, it is rare for an individually spiritual person to have drastic social ramifications for those around them. It is only when that person has others willing to rally to his call in some sort of organized religious opposition that one person's spiritual beliefs begin to have massive social ramifications. What I am basically trying to say is I think the increased support for suicide attacks following place of worship attendance rests primarily not in the increased social bonds, as the article seemed to suggest, but rather in the increased subservience to a small group of religious officials.

Which leads me to the second point which Cornucrapia mentioned which I full cede to him and should have mentioned myself. A far more powerful indicator of support for suicide bombings rests not in any test for religiosity, but rather in whether or not a region is occupied by a foreign military force. This then leads me to the other comment I wanted to address, which was Regan's. He thought my use of the words 'mentally unbalanced' was an unjustified value judgement, pointing out that the people who perform suicide attacks have usually led lives of terrible suffering.

There are two aspects to my response. The first is I just wanted to point out that though the way I said 'mentally unbalanced' was perhaps dismissive and marginalizing as it was within the bounds of a parentheses like an afterthought thrown out there, in that context it was not actually directed at suicide bombers in general. Instead, it was directed at those people who compose and enact suicide attacks on their own (sometimes with a friend, but the difference here is that they receive no external training or direct impetus driving them to perform their attack), for example the Columbine shooting. Despite the intention of the comment, however, I think that it is worth pointing out that anyone who perpetrates a suicide attack is mentally unbalanced. They might have good reason for being mentally unbalanced (such as having lived a horrifyingly awful life), but they are still deranged. A person driven insane by torture is still insane, and it should not be considered marginalizing to say so. It just happens that said person's insanity has a direct and understandable cause, but that does not mean that person does not most likely belongs in a mental health hospital. Regan makes an important point that is all too often unacknowledged in that one should be careful of falling into the trap of blaming the victim, but I think he oversteps the bounds of that point by objecting to any sort of assessment of suicide attackers' mental health based on the degree to which they have suffered prior to the attack. Much like war veterans who find they have difficulty returning to a nonviolent civilian existence and, as a result of their previous experiences, often end up commiting violent crimes against their fellow citizens, it is a messy issue. The people whose lives have been tragically and irrevocably disrupted by intense horror should not be dismissed out of hand, but so too should people not fear to assess their mental states. To deny that a person who is willing to blow himself up in order to kill others is mentally unbalanced out of pity for his past is dangerous both to him and those around him. To label him as mentally unbalanced should in no way be an attempt to marginalize him (though, like with all psychological problems, it will serve to do so for some people), but rather it should serve to acknowledge the horror of his prior experience and lead to future attempts to rectify that damage as much as possible.