Riddle Me This

I read an interesting blog post on the web. I didn't save the url. Fortunately, I didn't read it at a funeral. Google sends me to Snopes which debunks the claims copied and pasted below. It appears that they are made up and not based on any evidence from interviews of serial killers.

The alleged test

This is a genuine psychological test. It is a story about a girl. While at the funeral of her own mother, she met a guy whom she did not know.

She thought this guy was amazing, so much her dream guy she believed him to be, that she fell in love with him there and then … A few days later, the girl killed her own sister.

Question: What is her motive in killing her sister?

DON’T Scroll down until you have thought what your own answer is to this question!

*Answer: She was hoping that the guy would appear at the funeral again.

If you answered this correctly, you think like a psychopath. This was a test by a famous American psychologist used to test if one has the same mentality as a killer. Many arrested serial killers took part in this test and answered it correctly. If you didn’t answer correctly – good for you. If your friends hit the jackpot, may I suggest that you keep your distance. (If you got the answer correct, please let me know so I can take you off my distribution list…)

I had 3 guesses

1) We are talking about a murderous family. Maybe the girl finds out her sister killed their mother and killed her for revenge. the part about the dreamy guy is a coincidence.

2) Why kill a sister ? Maybe the sister is in a coma. The mother couldn't accept that she isn't waking up. With mother dead, the girl becomes next of kin and orders doctors to pull the plug. Here "killed" doesn't mean "murdered" as it was passive euthanasia. The dreamy guy is irrelevant to the killing

3) Girl finds out the dreamy guy is her sister's boyfriend and kills her sister as a romantic rival. New fact added & mother's funeral a coincidence.

So according to the test, I am not a serial killer (score one for the test -- I have never ever killed anyone).

However, I am a totally irriating twit who objects almost whenever he is told his answer isn't correct. I object that we can't know why real people really did things and certainly can't know why this hypothetical girl killed her hypothetical sister. The word "correctly" reveals something I find mildly interesting about the conventions of riddles.

The conventions include that the question does not describe irrelevant facts and that highly relevant unlikely facts are all described. My answers all assume that one of the facts (funeral or dreamy guy) is an irrelevant distraction. They aren't allowed in riddles (even if they are almost required in mystery stories). Also I always had to introduce an unlikely fact to get an explanation.

I think the phrasing of the question such that there is a correct answer is "how could these events cause the girl to murder her sister". The word "cause" implies they are each necessary (none an irrelevant distraction) and together they are sufficient (no need to think of another murder, relationship or health problem). I'm pretty sure I wouldn't have answered the correctly phrased riddle correctly.

I think the conventions of riddles are mildly interesting (so now I am not talking about murder or morality at all but about riddles). I think the conventions might explain results in congnitive psychology. Kahneman Tversky and many followers have discovered many ways in which people appear to be irrational. I know I am irrational, but I always worry if what they had there was a failure of communication

(an aside. this is a reference to Cool Hand Luke which is related to psychopaths, because the Luke character has all the superficial symptoms of a psychopath but isn't a psychopath and the warder has none of the symptoms and is a psychopath -- sorry will get back to congnitive now).

For example, I suspect that persistently bizarre statements about probabilities and choices among simple lotteries may be understood if we imagine two dialects -- English as spoken by probability theorists and ordinary English. So, in one sub dialect (frequentism) "90% probability" means if the experiment is repeated many times, the fraction of positive results will be close to 9 in 10. In plain English "90% probability" means supported by evidence but not proven. The dialect theory explains two anomalies. When people are asked for a 90% confidence interval about a measurement (say the area of lake Superior in hectares) about 50% of the intervals include the correct answer. Limited information should imply a very large 90% interval which is, nonetheless, a 90% interval. Also People pay too much attention to small probabilities of extreme events (cumulative prospect theory). Both make sense if ordinary English "90 % sure" corresponds to formal probability theory "50% sure".

So also, I think that errors of thought occur, because people assume the conventions of riddles. I call these errors, because I think they occur in real life, but when subjects treat a quiz question asked in a laboratory as a riddle, it isn't clear whether the subject or the psychologist is making a mistake. They have failed to communicate.

An example (from memory): there are 100 people in a room 90 lawyers and 10 engineers. Joe likes toy trains and is smart but not creative. Is it more likely he is a lawyer or an engineer". The typical answser is "engineer". I trust the honest psychologist actually checked that in a large sample the statements apply to more lawyers (must be self reported). Here the story is that people find numbers boring & respond more to words (especially ones which evoke images like "toy trains"). Another explanation is that, by the conventions of riddles, knowing the facts about trains, intelligence and creativity must be necessary to correctly answer the question.

Also damn Snopes. I think it would be interesting to actually evaluate the one question psychopath test.