Suit Preference Signals
The third type of defensive signal is called a Suit Preference Signal. These are the most elegant method of signalling, and have been used in bridge since the very beginning. They come into the picture when attitude and count signals don't apply. Knowing when to use which type of signalling is the hard part, but if you don't know what signal partner is trying to give you, you won't defeat many contracts. Certain times of the defence call for different signals, but one card can only give one signal, so don't try to make one card mean too many things.
There are times when you can see that partner needs your help in the defence, and suit preference signals work a treat here.
You're East, defending 4♥. Partner leads the ♦A and when you see the singleton in dummy, there are obviously no more tricks from that suit:
Partner needs your help to know what to do now. A guess about whether to switch to a spade or a club may work badly. If you play the ♦J on the ♦A (it's obviously not a true card), you're asking partner to switch to the higher-ranking suit, spades. If you'd played the ♦3 you would have been asking partner to play the lower-ranking suit clubs.
The ♦J can't be an attitude signal, and there's no reason to give a count card, so it must be a suit preference signal, and a high card asks for a shift to the higher-ranking of the two obvious suits, spades and clubs, i.e. spades. If partner switches to a spade, you'll take three quick tricks, but a club switch would be disastrous. However, if you change the layout to this:
Now you'd like a club returned, not a spade, so you should play the ♦3 on partner's ♦A, to ask for the lower-ranked suit.
Sometimes your partner needs to know how to reach your hand later in the play, i.e. where’s your entry. This is important when giving partner a ruff, or to know how to reach partner’s hand to take long suit winners at no trumps. Your card will ask partner to return either the higher-ranked suit, or the lower-ranked suit. Here's a hand:
North South are in 2♥. West leads the ♠A, and East plays the ♠9. West now plays the ♠K. East shows out, and West plays the ♠2, which is a suit preference signal for the lower remaining suit, clubs, rather than diamonds. After ruffing a spade, East returns a club to West's ♣A, and gets another ruff. Had West played the ♠10 for partner to trump, it would have asked for a diamond, the higher-ranked suit.
Signals are great tools, but they need to be combined with common sense, and we need to give partner a signal which will be the most useful one for the given situation. If you're thinking of what partner will need most in any given situation, you're working well in your defensive partnership.
Test your knowledge
The quiz below may not work properly on some mobile devices. If you are having trouble using it, please click here to open the quiz in its own wind