that's the ebu position, hence i edited my original comment to say i consider the ebu's stance to be harsh. i think mostly around the world, the partner of the psycher is allowed to try and work out what's going on when it's obvious that something's not right, and if he thinks the most likely culprit for the nonsensical nature of an auction is partner, he's allowed to take whatever action he sees fit, as long as that assessment isn't based on prior knowledge. the ebu's position seems to assume prior knowledge whenever the partner of a psycher makes a successful judgement. there shouldn't be any need to make such an assumption though - we collect psyche forms (i don't know how these are handled, admittedly) so any prior knowledge should become evident. as for why i think south can work out what's going on here, east is very unlikely to be making a psychic double as it will too often end the auction and result in a large number of doubled overtricks being scored up. this is presuming the double wasn't conventional.