The tiles of a typical modern Japanese mahjong set are made of nylon and the suits, winds and dragons are stamped or carved onto the tile faces. Not only can the different tiles be told apart from one another by a quick glance, they also FEEL different if you rub your thumb over them,
And rub his thumb across the face of the tile is what many an expert Japanese player of mahjong likes to do during the course of a game! Yes, many an experienced player has developed the ability to "read" tiles with his thumb by rubbing it across the tile face and feeling the indentations.
It takes hours of practice to get to the point where you can accurately distinguish each of the 34 different tile faces of a standard Japanese mahjong set with your thumb, and there seems to be little advantage in being able to do so. It is a diverting party trick and it also adds some kudos to a player's game if the player can pluck a tile from the wall, announce what it is and discard it without so much as glancing at it. Mahjong is most exciting when played swiftly, so being able to read a tile without looking at it may be said to help the cause of speedy play, but apart from that there does not seem to be much practical profit in taking the trouble to learn the skill.
However, in one instance that I can think of some small advantage could be gained about an opponent's tile by use of the "thumb-reading" technique. Experienced mahjong players enjoy playing a fast-paced game so if one player hesitates before discarding a tile, the player to his right is likely to have reached for "his" tile on the end of the wall before the first player has discarded. By placing his thumb under the tile in readiness to lift it off the wall, a competent "thumb-reader" would be able to read the tile while waiting for his turn.
But then, when the player on his left discards a tile, if another player claims it as a "Pon" the "thumb-reader" would not in fact draw the tile from the wall and it is more than likely that the tile will go to a different player. In that case the "thumb reader" will know what the tile is and will perhaps pay attention to where it is placed in the other player's hand.
Some people might object that such a practice is a form of cheating, but others counter that it is just part parcel of the Japanese approach to the game.
It might also be pointed out that there is nothing to stop the player who received the tile from practising some deception by placing it somewhere in his hand where it does not really belong in the hope that the "thumb-reader" will draw the wrong conclusions about the make-up of his hand.
Whatever your attitude towards players reading tiles with their thumbs may be, that it can be done at all shows you how sensitive the human thumb - or "oya-yubi" in Japanese - can be.
This is the place where I try to persuade you, my fellow Japanese mahjong fanatic, that you ought to hot foot it over to my website, Japanese-Games-Shop.com and blow a large chunk of your hard earned wages (or ill gotten gains) on a seriously expensive, exclusive, utterly exotic, Japanese mahjong set. I recommend the Nintendo Yakuman New Ivory Japanese Mahjong Set, possibly the most expensive Japanese mahjong set this side of the Milky Way.