Hacker News new | past | comments | ask | show | jobs | submit login

"Four cards were placed on a table: [D K 3 7] The participants were given the following instructions: Here is a rule: “every card that has a D on one side has a 3 on the other.” Your task is to select all those cards, but only those cards, which you would have to turn over in order to discover whether or not the rule has been violated. The correct answer is to pick the D card and the 7 card,..."

Wait a minute, this is wrong! You have to check the K card also, since it could have a D on the hidden side. Only if you were given the instruction, which is done later, that all cards have a number and a letter on one side, you know that the K card must have a letter on the hidden side.




I think it's given that there is a letter on one side and a number on the other side if every card and implicitly, that that rule hasn't been broken, otherwise you have to check every card to see that there's no emoji there


We have to make sure, that if there is a "D" on one side, there must be a "3" on the other side. If we see a "3", we are done, otherwise if there is not a "3" we have to check that there is no "D" on the hidden side. Hence we have to check exactly all cards facing a "3".


No, because the framing of the problem includes a statement that if there is a letter on one side then there is a number on the other and vice versa. The K can't have a D on the other side unless they're lying in the problem statement (which would defeat the purpose of the experiment, so why would they and why would you assume they are?).


I now how the experiment was conducted. That wasn't the question either. Read carefully what i have cited. There is nothing about what you have said. If you specify something, you ought to be very precise :-)


> Participating subjects were shown a selection of cards, each of which had a letter on one side and a number on the other.

You skipped that part just above your quote. There is no ambiguity. In both this experiment and the original experiment they were given that information before their selection.


Quoted sentence does not support your claim.


beyondCritics was attempting to be pedantic, and failing due to not reading, that the problem in this linked article was not presented with the context that the cards were always letter/number pairs and never letter/letter pairs (in which case you'd need to check the K card). Just a few sentences earlier in the article from what they quoted, though, it presents what I quoted, that the cards are letter/number pairs.

To support my claim though:

From the experiment in the linked article:

> Four cards are placed on a table in front of you. Each card has a letter on one side and a number on the other.

That statement is included in the text provided to participants.

From the original experiment:

> The subjects were told that cards with letters on their front had numbers on their back and vice versa.

Subjects were tested only after being given this information. Satisfied?

https://web.mit.edu/curhan/www/docs/Articles/biases/20_Quart...




Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact

Search: