This is a mixture of Martingale and Insurance systems. Bets are raised one unit after each losing bet and lowered one unit after each winning bet. The sequence and amount raised or lowered can be varied to suit particular games and odds.
The negative progression system requires that you to bet more when you're losing. This type of system also occurs in the investing industry and is termed 'The Martingale Sysytem', just as it is in gambling circles. The principles of betting more or taking greater risks whilst losing are the same in both industries.
The D'Alenbert system, the Labouchere and the Martingale systems all belong under the negative progression sytems category. These sytems requires more capital and are far riskier than the positive systems.
Insurance betting systems are where you decrease the amount of your bet when you win, usually following a high initial bet or following short 'let-it-ride' progressive wins. This system is technically playing it safe and is a good compromise.