diff --git a/metagpt/roles/product_manager.py b/metagpt/roles/product_manager.py
index bc6771829..966115c0f 100644
--- a/metagpt/roles/product_manager.py
+++ b/metagpt/roles/product_manager.py
@@ -50,3 +50,6 @@ class ProductManager(Role):
         else:
             self._set_state(0)
         return self._rc.todo
+
+    async def _observe(self, ignore_memory=False) -> int:
+        return await super(ProductManager, self)._observe(ignore_memory=True)
diff --git a/metagpt/roles/role.py b/metagpt/roles/role.py
index 1c9da7e6c..fe121ed1a 100644
--- a/metagpt/roles/role.py
+++ b/metagpt/roles/role.py
@@ -218,12 +218,12 @@ class Role:
 
         return msg
 
-    async def _observe(self) -> int:
+    async def _observe(self, ignore_memory=False) -> int:
         """Prepare new messages for processing from the message buffer and other sources."""
         # Read unprocessed messages from the msg buffer.
         news = self._rc.msg_buffer.pop_all()
         # Store the read messages in your own memory to prevent duplicate processing.
-        old_messages = self._rc.memory.get()
+        old_messages = [] if ignore_memory else self._rc.memory.get()
         self._rc.memory.add_batch(news)
         # Filter out messages of interest.
         self._rc.news = [n for n in news if n.cause_by in self._rc.watch and n not in old_messages]