diff --git a/src/graphomotor/core/models.py b/src/graphomotor/core/models.py
index 34aaa61..73dccc1 100644
--- a/src/graphomotor/core/models.py
+++ b/src/graphomotor/core/models.py
@@ -189,7 +189,6 @@ class LineSegment:
     points: pd.DataFrame
     is_error: bool
     line_number: int
-    ink_points: np.ndarray = dataclasses.field(default_factory=lambda: np.array([]))
 
     ink_time: float = 0.0
     think_time: float = 0.0
@@ -203,6 +202,7 @@ class LineSegment:
     hesitation_duration: float = 0.0
     velocities: List[float] = dataclasses.field(default_factory=list)
     accelerations: List[float] = dataclasses.field(default_factory=list)
+    ink_points: pd.DataFrame = dataclasses.field(default_factory=pd.DataFrame)
 
     def valid_ink_trajectory(
         self,
@@ -230,7 +230,7 @@ def valid_ink_trajectory(
             end_circle: CircleTarget representing the end circle.
 
         Returns:
-            Tuple of (ink_start_idx: int, ink_end_idx: int) if valid
+            Tuple of (ink_start_idx: Optional[int], ink_end_idx: Optional[int]) if valid
             trajectory exists, else (None, None).
         """
         ink_start_idx = None
@@ -248,7 +248,6 @@ def valid_ink_trajectory(
             ):
                 ink_end_idx = idx
                 break
-
         if (
             ink_start_idx is not None
             and ink_end_idx is not None
@@ -292,16 +291,15 @@ def calculate_path_optimality(
             self.path_optimality = optimal_distance / self.distance
         return
 
-    def calculate_velocity_metrics(self, ink_points: pd.DataFrame) -> None:
-        """Get distance, velocity, and acceleration metrics of a LineSegment.
+    def calculate_velocity_metrics(self) -> None:
+        """Get velocity metrics of a LineSegment.
 
         Args:
             self: LineSegment object to calculate velocities for.
-            ink_points: DataFrame of ink points with 'x', 'y', and 'seconds' columns.
         """
-        dx = np.diff(ink_points["x"].values)
-        dy = np.diff(ink_points["y"].values)
-        dt = np.diff(ink_points["seconds"].values)
+        dx = np.diff(self.ink_points["x"].values)
+        dy = np.diff(self.ink_points["y"].values)
+        dt = np.diff(self.ink_points["seconds"].values)
 
         distances = np.sqrt(dx**2 + dy**2)
         self.distance = np.sum(distances)
@@ -316,3 +314,41 @@ def calculate_velocity_metrics(self, ink_points: pd.DataFrame) -> None:
             self.accelerations = np.diff(velocities).tolist()
 
         return
+
+    def detect_hesitations(self, threshold_percentile: int = 20) -> None:
+        """Detect hesitations as periods of significantly reduced velocity.
+
+        This function defines a hesitation as any period where the velocity falls below
+        a certain threshold, which is determined by the specified percentile of the
+        velocity distribution. It counts the number of distinct hesitation periods and
+        adds 1 if the line starts with a hesitation. It also calculates the total
+        duration of hesitations based on the number of points that fall below the
+        threshold and the time interval between points.
+
+        hesitation_count defaults to 0 and hesitation_duration defaults to 0.0 in the
+        LineSegment object if there are less than 3 velocity points. This function also
+        assumes uniform sampling.
+
+        Args:
+            threshold_percentile: Percentile to determine the velocity threshold for
+                hesitations (default is 20, meaning the bottom 20% of velocities are
+                considered hesitations).
+        """
+        if len(self.velocities) < 3:
+            return
+
+        dt = np.diff(self.ink_points["seconds"].values)
+
+        threshold_velocity = np.percentile(self.velocities, threshold_percentile)
+        hesitations = self.velocities < threshold_velocity
+
+        hesitation_changes = np.diff(hesitations.astype(int))
+        hesitation_count = np.sum(hesitation_changes == 1)
+
+        if hesitations[0]:
+            hesitation_count += 1
+
+        self.hesitation_count = hesitation_count
+        self.hesitation_duration = np.sum(hesitations) * dt[0]
+
+        return
diff --git a/tests/unit/test_models.py b/tests/unit/test_models.py
index 00875ac..d78ee1a 100644
--- a/tests/unit/test_models.py
+++ b/tests/unit/test_models.py
@@ -3,7 +3,6 @@
 import datetime
 from typing import Dict, cast
 
-import numpy as np
 import pandas as pd
 import pytest
 
@@ -256,15 +255,16 @@ def test_uniform_motion() -> None:
         points=points,
         is_error=False,
         line_number=1,
+        ink_points=points,  # Pre-assign ink_points for velocity calculation
     )
 
-    segment.calculate_velocity_metrics(points)
+    segment.calculate_velocity_metrics()
 
     assert segment.distance == 3.0
     assert segment.mean_speed == 1.0
     assert segment.speed_variance == 0.0
-    assert np.all(segment.velocities) == 1.0
-    assert np.all(segment.accelerations) == 0.0
+    assert segment.velocities == [1.0, 1.0, 1.0]
+    assert segment.accelerations == [0.0, 0.0]
 
 
 def test_accelerating_motion() -> None:
@@ -282,13 +282,14 @@ def test_accelerating_motion() -> None:
         points=points,
         is_error=False,
         line_number=1,
+        ink_points=points,  # Pre-assign ink_points for velocity calculation
     )
 
-    segment.calculate_velocity_metrics(points)
+    segment.calculate_velocity_metrics()
 
     assert segment.distance == 9.0
     assert segment.mean_speed == 3.0
-    assert segment.speed_variance == pytest.approx(2.6666666666666665)
+    assert segment.speed_variance > 0.0
     assert segment.velocities == [1.0, 3.0, 5.0]
     assert segment.accelerations == [2.0, 2.0]
 
@@ -308,15 +309,16 @@ def test_velocity_two_points_only() -> None:
         points=points,
         is_error=False,
         line_number=1,
+        ink_points=points,  # Pre-assign ink_points for velocity calculation
     )
 
-    segment.calculate_velocity_metrics(points)
+    segment.calculate_velocity_metrics()
 
     assert segment.distance == 5.0
     assert segment.mean_speed == 2.5
     assert segment.speed_variance == 0.0
     assert segment.velocities == [2.5]
-    assert segment.accelerations == []
+    assert segment.accelerations == []  # No acceleration with only one velocity point
 
 
 def test_decelerating_motion() -> None:
@@ -334,9 +336,10 @@ def test_decelerating_motion() -> None:
         points=points,
         is_error=False,
         line_number=1,
+        ink_points=points,  # Pre-assign ink_points for velocity calculation
     )
 
-    segment.calculate_velocity_metrics(points)
+    segment.calculate_velocity_metrics()
 
     assert segment.distance == 9.0
     assert segment.mean_speed == 3.0
@@ -360,12 +363,113 @@ def test_stationary_motion() -> None:
         points=points,
         is_error=False,
         line_number=1,
+        ink_points=points,  # Pre-assign ink_points for velocity calculation
     )
 
-    segment.calculate_velocity_metrics(points)
+    segment.calculate_velocity_metrics()
 
     assert segment.distance == 0.0
     assert segment.mean_speed == 0.0
     assert segment.speed_variance == 0.0
     assert segment.velocities == [0.0, 0.0]
     assert segment.accelerations == [0.0]
+
+
+def test_no_hesitations_uniform_motion() -> None:
+    """Test with uniform motion where all velocities are equal."""
+    points = pd.DataFrame(
+        {
+            "x": [0, 1, 2, 3],
+            "y": [0, 0, 0, 0],
+            "seconds": [0, 1, 2, 3],
+        }
+    )
+    segment = models.LineSegment(
+        start_label="1",
+        end_label="2",
+        points=points,
+        is_error=False,
+        line_number=1,
+        ink_points=points,  # Pre-assign ink_points for velocity calculation
+    )
+
+    segment.calculate_velocity_metrics()
+    segment.detect_hesitations()
+
+    assert segment.hesitation_count == 0
+    assert segment.hesitation_duration == 0.0
+
+
+def test_hesitation_at_start() -> None:
+    """Test when the line starts with a hesitation."""
+    points = pd.DataFrame(
+        {
+            "x": [0, 0.1, 1, 2],
+            "y": [0, 0.1, 0, 0],
+            "seconds": [0, 1, 2, 3],
+        }
+    )
+    segment = models.LineSegment(
+        start_label="1",
+        end_label="2",
+        points=points,
+        is_error=False,
+        line_number=1,
+        ink_points=points,  # Pre-assign ink_points for velocity calculation
+    )
+
+    segment.calculate_velocity_metrics()
+    segment.detect_hesitations()
+
+    assert segment.hesitation_count == 1
+    assert segment.hesitation_duration == 1.0
+
+
+def test_multiple_hesitations() -> None:
+    """Test when there are multiple hesitation periods."""
+    points = pd.DataFrame(
+        {
+            "x": [0, 100, 100.1, 200, 200.1, 300, 400, 500, 600],
+            "y": [0, 0, 0, 0, 0, 0, 0, 0, 0],
+            "seconds": [0, 1, 2, 3, 4, 5, 6, 7, 8],
+        }
+    )
+    segment = models.LineSegment(
+        start_label="1",
+        end_label="2",
+        points=points,
+        is_error=False,
+        line_number=1,
+        ink_points=points,  # Pre-assign ink_points for velocity calculation
+    )
+
+    segment.calculate_velocity_metrics()
+    segment.detect_hesitations()
+
+    assert segment.hesitation_count == 2
+    assert segment.hesitation_duration == 2.0
+
+
+def test_less_than_three_velocities() -> None:
+    """Test early return when velocities length is less than 3."""
+    points = pd.DataFrame(
+        {
+            "x": [0, 1],
+            "y": [0, 0],
+            "seconds": [0, 1],
+        }
+    )
+    segment = models.LineSegment(
+        start_label="1",
+        end_label="2",
+        points=points,
+        is_error=False,
+        line_number=1,
+        ink_points=points,  # Pre-assign ink_points for velocity calculation
+    )
+
+    segment.calculate_velocity_metrics()
+    segment.detect_hesitations()
+
+    assert segment.hesitation_count == 0
+    assert segment.hesitation_duration == 0.0