diff --git a/src/graphomotor/features/trails/time.py b/src/graphomotor/features/trails/time.py
new file mode 100644
index 0000000..4babc3e
--- /dev/null
+++ b/src/graphomotor/features/trails/time.py
@@ -0,0 +1,52 @@
+"""Feature extraction module for time-based metrics in trails drawing data."""
+
+from graphomotor.core import models
+
+
+def calculate_total_error_time(drawing: models.Drawing) -> dict[str, float]:
+    """Calculate the total time spent making errors.
+
+    A contiguous "error chunk" is any sequence of rows where df["error"] != "E0".
+    The start and end of each chunk is defined as the midpoint between the last
+    timestamp with a "correct" entry and the first timestamp of an "error". The total
+    error time is the sum of the durations of all error chunks.
+
+    Args:
+        drawing: Drawing object containing drawing data.
+
+    Returns:
+        Dictionary containing the total time (s) spent in error states.
+    """
+    mask = drawing.data["error"] != "E0"
+    if not mask.any():
+        return {"total_error_time": 0.0}
+
+    error_change = mask.astype(int).diff()
+    chunk_starts = error_change[error_change == 1].index.tolist()
+    chunk_ends = error_change[error_change == -1].index.tolist()
+
+    if mask.iloc[0]:
+        chunk_starts = [0] + chunk_starts
+
+    if mask.iloc[-1]:
+        chunk_ends = chunk_ends + [len(drawing.data)]
+
+    seconds = drawing.data["seconds"].to_numpy()
+    total_error_time = 0.0
+
+    for start_idx, end_idx in zip(chunk_starts, chunk_ends):
+        start_time = (
+            (seconds[start_idx - 1] + seconds[start_idx]) / 2
+            if start_idx > 0
+            else seconds[0]
+        )
+
+        end_time = (
+            (seconds[end_idx - 1] + seconds[end_idx]) / 2
+            if end_idx < len(seconds)
+            else seconds[-1]
+        )
+
+        total_error_time += end_time - start_time
+
+    return {"total_error_time": float(total_error_time)}
diff --git a/tests/unit/test_trails_time.py b/tests/unit/test_trails_time.py
new file mode 100644
index 0000000..fca1e1b
--- /dev/null
+++ b/tests/unit/test_trails_time.py
@@ -0,0 +1,73 @@
+"""Tests for trails time.py."""
+
+import pandas as pd
+
+from graphomotor.core import models
+from graphomotor.features.trails import time
+
+
+def test_total_error_time_no_errors() -> None:
+    """Test case with no errors."""
+    df = pd.DataFrame(
+        {
+            "error": ["E0", "E0", "E0", "E0"],
+            "seconds": [0, 1, 2, 3],
+        }
+    )
+    drawing = models.Drawing(data=df, task_name="trails", metadata={"id": "5555555"})
+
+    result = time.calculate_total_error_time(drawing)
+    assert result == {"total_error_time": 0.0}
+
+
+def test_single_error_chunk() -> None:
+    """Test case with a single error chunk."""
+    df = pd.DataFrame(
+        {
+            "error": ["E0", "E1", "E1", "E0", "E0"],
+            "seconds": [0.0, 1.0, 3.0, 5.0, 6.0],
+        }
+    )
+    drawing = models.Drawing(data=df, task_name="trails", metadata={"id": "5555555"})
+
+    result = time.calculate_total_error_time(drawing)
+    assert result == {"total_error_time": 3.5}
+
+
+def test_multiple_error_chunks() -> None:
+    """Test case with multiple error chunks."""
+    df = pd.DataFrame(
+        {
+            "error": ["E0", "E1", "E1", "E0", "E2", "E2", "E0"],
+            "seconds": [0, 1, 3, 5, 6, 7, 9],
+        }
+    )
+    drawing = models.Drawing(data=df, task_name="trails", metadata={"id": "5555555"})
+    result = time.calculate_total_error_time(drawing)
+    assert result == {"total_error_time": 6.0}
+
+
+def test_error_at_end() -> None:
+    """Test case with an error chunk that goes to the end of the drawing."""
+    df = pd.DataFrame(
+        {
+            "error": ["E0", "E0", "E2", "E2"],
+            "seconds": [0.0, 1.0, 2.0, 4.0],
+        }
+    )
+    drawing = models.Drawing(data=df, task_name="trails", metadata={"id": "5555555"})
+    result = time.calculate_total_error_time(drawing)
+    assert result == {"total_error_time": 2.5}
+
+
+def test_error_at_start() -> None:
+    """Test case with an error chunk that starts at the beginning of the drawing."""
+    df = pd.DataFrame(
+        {
+            "error": ["E1", "E1", "E0", "E0"],
+            "seconds": [0.0, 1.0, 3.0, 4.0],
+        }
+    )
+    drawing = models.Drawing(data=df, task_name="trails", metadata={"id": "5555555"})
+    result = time.calculate_total_error_time(drawing)
+    assert result == {"total_error_time": 2.0}