Towser`s explanation is very good, Also on the Embraer the spoilers help the fly by wire, fly the aircraft at a more comfortable attitude. With out it the nose would be pointing down at at a greater angle and it would feel uncomfortable in the cabin. The spoilers are also very clever on the Embraer and are active during the approach. If you watch them on a bumpy day they go in and out alot in reaction to the pitch of the aircraft to keep everything in balance.