31 May 2010

O Brave New World

Two articles caught my eye recently. I paraphrase them briefly here, but read the linked articles if you haven't heard about this in the news already.

  • Oxytocin, when administered via nose spray, increased empathy in subjects in a study published in The Journal of Neuroscience. Discoblog has an interpretation of the findings.
  • Magnets can interfere with moral judgments, according to a study published in the Proceedings of the National Academy of Sciences. A technique called transcranial magnetic stimulation changed the way participants reacted to stories designed to provoke moral reactions about guilt or innocence. NPR has a summary.

You can probably, without thinking too hard, come up with half a dozen ways in which these techniques could be misused for nefarious purposes. The reported findings only represent "proof of concept," but I believe it's only a matter of time before these or similar techniques are commonly applied to unwilling subjects.

I, for one, was not really surprised to learn that scientists are getting closer to identifying a neurological/biochemical basis for relatively high-level mental functions. What's so amazing to me is the relative subtlety of these techniques. Time was when you had to jab someone in the arm or put something in their drink or apply blunt head trauma in order to compromise their mental faculties, and even then only you could only manipulate them in a very coarse-grained way (see, e.g. sodium pentothal). I am very worried that in twenty years you'll have to check under the tables for aerosolizers and neural stimulation devices every time you walk into a corporate board room or a courtroom or a car dealership.

16 May 2010

How not to misinterpret statistics

ScienceNews has an article by Tom Siegfried, titled "Odds Are, It's Wrong". Siegfried presents a pretty good analysis of a few common errors in statistics (just be sure to skip over the overdramatic introduction). The most major of these, in my mind, is misunderstanding the meaning of statistical significance.

If you've forgotten everything you learned in your last statistics class and are a bit hazy about what the difference is between these two statements,

Experimental data yielded a p-value of 0.03.

With 97% certainty, the observed difference between the groups was real (and not due to chance).

...then this article may help.

09 May 2010

Blacklists

From Sacramento Credit Union's FAQ:

Why are the Security Questions used?
The first time you login and enroll in Protection Plus, you will be asked to enter five Security Questions and corresponding answers. The Security Questions are used if you do not want to register the computer you are currently using. With the Security Questions, we can make sure it is you logging in when you use different computers, such as, a internet bar computer. The answers to your Security Questions are case sensitive and cannot contain special characters like an apostrophe, or the words "insert," "delete," "drop," "update," "null," or "select."
Why can't I use certain words like "drop" as part of my Security Question answers?
There are certain words used by hackers to try to gain access to systems and manipulate data; therefore, the following words are restricted: "select," "delete," "update," "insert," "drop" and "null".

I suppose that superficially this explanation is reassuring, but what it suggests about the underlying implementation is both saddening and terrifying.

(Blacklisting is often the wrong approach.)

04 May 2010

Rush Hour is PSPACE-complete

A friend got me playing the Traffic Jam game for Android, which is a clone of the children's game Rush Hour:

The object is to move the cars around so that the yellow car can exit the board; each car may move vertically or horizontally but not both.

I was amused (though not totally surprised) to learn that when one considers the generalization of this game to larger boards, it is NP-hard and PSPACE-complete to decide whether a configuration is solvable or not. Flake and Baum, in a 2002 paper (subtitle: "Why you should generously tip parking lot attendants"), prove this by showing how to emulate certain classes of digital circuitry in Rush Hour. This paper is worth a look even if you are only inclined to glance at the pictures of the constructions. The authors built freaking digital logic out of cars.

As with many good games, it seems there is more to Rush Hour than meets the eye.