The study looked at how government spending is affected by changes in public debt and the business cycle in 18 OECD countries. They found that government spending multipliers are higher during recessions than in times of economic growth. When public debt increases during recessions, the impact on government spending is greater compared to debt accumulation during economic expansions. This suggests that in times of economic growth, increasing public debt may lead to lower government spending multipliers due to factors like higher expected interest rates and crowding-out effects.