 After checking the circuit breakers for the source of the warnings, the crew reduced thrust to lower the speed of the plane.This action immediately triggered the 757's stick-shaker stall alert, warning the confused pilots that the aircraft was flying dangerously slow, just seconds after the indicators had warned them that the speed was too high.The co-pilot and the relief pilot both seemed to recognise the approaching stall and tried to tell the captain, but did not intervene directly, possibly out of deference to the captain's age and experience.