Inflation expectations play a crucial role in how effective monetary policy is during a liquidity trap. Different ways of forming these expectations can impact the outcomes of monetary policies like the Taylor rule or price-level targeting. When a central bank follows the optimal commitment policy, how inflation expectations are formed matters less. However, for other rules, like the Taylor rule, it becomes critical. In the Japanese economy, the effects of monetary policy on economic dynamics change significantly based on how inflation expectations are shaped under different rules.