THOG problem
Encyclopedia
The THOG problem is one of Peter Wason's logic puzzles, constructed to show some of the weaknesses in human thinking.
You are shown four symbols
and told by the experimenter "I have picked a colour (black or white) and a shape (square or circle). A symbol that possesses exactly one of these properties, is a THOG. The black circle is a THOG. What can be said about the other symbols? Which one is the symbol I picked, or THOG, not-THOG, or undecidable?"
Presented in this form, the task is quite difficult, because many informations must be held in working memory
at the same time. A first step towards a solution is rephrasing the first sentence of the experimenter's statement to "I have picked one of the symbols". It cannot be the black circle, which, being a THOG, possesses only one of the required properties. The chosen symbol must be the black square or the white circle. The white square, being the "opposite" of the black circle, also has exactly one of the required properties, making it a THOG.
You are shown four symbols
- a black square
- a white square
- a black circle
- a white circle
and told by the experimenter "I have picked a colour (black or white) and a shape (square or circle). A symbol that possesses exactly one of these properties, is a THOG. The black circle is a THOG. What can be said about the other symbols? Which one is the symbol I picked, or THOG, not-THOG, or undecidable?"
Presented in this form, the task is quite difficult, because many informations must be held in working memory
Working memory
Working memory has been defined as the system which actively holds information in the mind to do verbal and nonverbal tasks such as reasoning and comprehension, and to make it available for further information processing...
at the same time. A first step towards a solution is rephrasing the first sentence of the experimenter's statement to "I have picked one of the symbols". It cannot be the black circle, which, being a THOG, possesses only one of the required properties. The chosen symbol must be the black square or the white circle. The white square, being the "opposite" of the black circle, also has exactly one of the required properties, making it a THOG.