In Reply to: Put on my thinking cap posted by Alan Bradshaw on November 22, 2008 at 08:57:
: Can anyone confirm the widely held belief that the origin of the phrase "put on my thinking cap" comes from an Oxford University undergraduate common room where the fellows would sit and mull over some problem and were constantly having their train of thought interrupted, so they devised the simple rule that if one were sitting ruminating with a cap on, then they were not to be disturbed. The caps used became known as thinking caps - thus was the phrase born.
That's a possibility, although I can't find any evidence to support it. If Oxford students did wear such caps they would have been under the name of 'considering cap', rather than 'thinking cap. See: