Two old friends, Fred and Ted, had managed to work a party piece that no one could figure out. Fred would go out of the room, and Ted would invite the guests to select an item. They were then asked to continue to think of it so that Fred could read their minds. Fred would be blindfolded so that there could be no possibility of visual clues. Ted would then start to ask Fred questions:

On one occasion Ted asked:
"Did we think of the word sock?"
"Absolutely not." replied Fred.
"Well, was it an ashtray?"
"No."
"OK, is it the word plate?"
Again the answer was negative.
"So, are we thinking of the word china?"
"No." replied Fred.
"Are we thinking of the word carpet?"
"No," replied Fred, " the word you are thinking of is chair."

Everyone gasped. He was right.

How did Fred and Ted work their party piece?