fix error in posterior updates with multiple value children with unob…

…served values (ComputationalPsychiatry#208)

src/pyhgf/updates/posterior/continuous.py

@@ -348,21 +348,17 @@ def posterior_update_precision_continuous_node(
         # sum the prediction errors from both value and volatility coupling
         precision_weigthed_prediction_error = 0.0
 
-        # Value coupling updates - update the precision of a value parent
-        # ---------------------------------------------------------------
-        if edges[node_idx].value_children is not None:
-            for value_child_idx, value_coupling in zip(
-                edges[node_idx].value_children,  # type: ignore
-                attributes[node_idx]["value_coupling_children"],
-            ):
-                precision_weigthed_prediction_error += (
-                    value_coupling**2 * attributes[value_child_idx]["expected_precision"]
-                )
-
-                # cancel the prediction error if the child value was not observed
-                precision_weigthed_prediction_error *= attributes[value_child_idx][
-                    "observed"
-                ]
+    # Value coupling updates - update the precision of a value parent
+    # ---------------------------------------------------------------
+    if edges[node_idx].value_children is not None:
+        for value_child_idx, value_coupling in zip(
+            edges[node_idx].value_children,  # type: ignore
+            attributes[node_idx]["value_coupling_children"],
+        ):
+            # cancel the prediction error if the child value was not observed
+            precision_weigthed_prediction_error += (
+                value_coupling**2 * attributes[value_child_idx]["expected_precision"]
+            ) * attributes[value_child_idx]["observed"]
 
         # Volatility coupling updates - update the precision of a volatility parent
         # -------------------------------------------------------------------------
@@ -381,21 +377,17 @@ def posterior_update_precision_continuous_node(
                     "volatility_prediction_error"
                 ]
 
-                # sum over all volatility children
-                precision_weigthed_prediction_error += (
-                    0.5 * (volatility_coupling * effective_precision) ** 2
-                    + (volatility_coupling * effective_precision) ** 2
-                    * volatility_prediction_error
-                    - 0.5
-                    * volatility_coupling**2
-                    * effective_precision
-                    * volatility_prediction_error
-                )
-
-                # cancel the prediction error if the child value was not observed
-                precision_weigthed_prediction_error *= attributes[volatility_child_idx][
-                    "observed"
-                ]
+            # sum over all volatility children
+            # cancel the prediction error if the child value was not observed
+            precision_weigthed_prediction_error += (
+                0.5 * (volatility_coupling * effective_precision) ** 2
+                + (volatility_coupling * effective_precision) ** 2
+                * volatility_prediction_error
+                - 0.5
+                * volatility_coupling**2
+                * effective_precision
+                * volatility_prediction_error
+            ) * attributes[volatility_child_idx]["observed"]
 
         # Compute the new posterior precision
         # using value prediction errors from both value and volatility coupling