Among the many characteristics examined in forensic handwriting identification, Line Quality is, in my opinion, one of the most significant, and at the same time one of the most underestimated.
Why is it underestimated?
Because the human eye is naturally attracted to Pictorial Appearance.
When people compare two signatures, they instinctively look at the visible image before them. They compare the overall appearance, the shape of the letters, the size of the writing, the slant and the general pattern of the signature. From those obvious observations they begin searching for similarities and differences.
Those characteristics are undoubtedly important, and I shall discuss Pictorial Appearance in a separate article.
However, they do not answer the most important forensic question:
Was the writing produced naturally?
In many cases, the answer lies not in the appearance of the handwriting itself, but in the quality of the movement that produced it.
That quality is known as Line Quality.
What Is Line Quality?
Handwriting is the physical expression of a remarkably complex neurological process.
The brain activates the nervous system, which coordinates the muscles of the shoulder, arm, wrist, hand and fingers to produce writing movements that have become deeply established through years of repetition.
The formation of letters, connecting strokes, symbols and signature movements are physical expressions of mental patterns that have become habitual.
These patterns are repeated so frequently that they are executed automatically, without conscious attention to the formation of individual strokes.
Every writer gradually develops a unique way of holding the pen, moving it across the paper and coordinating those movements.
The result is a personal writing style that becomes remarkably consistent throughout life.
When Drawing Becomes Habit
A child first learns to write by consciously drawing letters.
Every stroke requires attention.
Every movement is deliberate.
With repetition, those carefully constructed drawings gradually become automatic writing habits.
Eventually, the writer no longer thinks about how each stroke is formed.
The writing simply flows.
A signature develops in much the same way.
Although a signature may eventually appear as a complex design or even as an abstract scribble, it is no longer consciously drawn. It has become an unconscious motor habit.
Ironically, a person attempting to imitate another person's signature often reverses this natural process.
Instead of writing habitually, the forger begins to draw the signature.
The result may resemble the genuine signature in appearance, but it frequently lacks the natural movement that characterises genuine writing.
What Creates Good Line Quality?
Good Line Quality is the visible result of natural writing movement.
It is characterised by smooth, spontaneous and uninterrupted pen movement.
Among its principal characteristics are:
- natural fluency and rhythm;
- smooth, continuous movement;
- appropriate writing speed;
- natural coordination;
- consistent pressure patterns;
- absence of hesitation;
- absence of tremor;
- absence of patching;
- absence of unnecessary pen lifts; and
- absence of slow, carefully constructed stroke formation.
Good Line Quality reflects natural writing.
Poor Line Quality reflects interference with that natural process.
What Produces Poor Line Quality?
Poor Line Quality develops whenever the natural writing movement is interrupted.
Sometimes the explanation is entirely innocent.
At other times it may indicate simulation or forgery.
Among the possible causes are:
- slow or hesitant execution;
- tremulous movement;
- tracing;
- patching;
- disguise;
- excessive conscious control;
- nervousness or emotional stress;
- neurological or medical conditions;
- fatigue;
- alcohol or drugs;
- unsuitable writing instruments; or
- poor writing surfaces.
For this reason, poor Line Quality should never be interpreted in isolation.
Its significance must always be evaluated together with every other handwriting characteristic.
Why Forgers Struggle
A person attempting to imitate another person's signature usually concentrates on its visible appearance.
The objective is obvious, and understandable.
The forger tries to reproduce the shape of the genuine signature as accurately as possible.
The difficulty is that handwriting is far more than shape.
No former, however skilled, can completely reproduce another person's unconscious writing habits.
Indeed, even the genuine writer cannot consciously reproduce every unconscious movement that occurs during the natural execution of his or her own signature.
Those movements belong to the writer's habitual motor system rather than to conscious thought.
For this reason, two signatures that appear almost identical may have been produced by entirely different writing processes.
Conversely, two genuine signatures that appear noticeably different may nevertheless display the same natural Line Quality.
This is often where the most significant forensic evidence is found.
Looking Beyond Shape
Many handwriting comparisons begin with the question:
"Do these two signatures look alike?"
That is a reasonable starting point.
It should never be the final question.
Professional forensic document examination seeks to determine not merely what the writing looks like, but how it was produced.
Pictorial Appearance forms only one part of the available evidence.
The writing process that produced that appearance is frequently of even greater forensic significance.
Beyond the Obvious
The obvious observation is:
"These two signatures look similar."
The professional question is:
"Were they produced in the same natural manner?"
The obvious observation is:
"The letters are different."
The professional question is:
"Do those differences represent natural variation, or do they possess evidential significance?"
Professional forensic document examination is not simply the comparison of shapes.
It is the interpretation of the writing process that produced those shapes.
An experienced examiner does not merely identify handwriting characteristics.
The examiner determines and explains their evidential significance.
Looking Beyond the Obvious begins when attention shifts from what was written to how it was written.
If Line Quality explains how the writing was produced, another two questions arise: How important is the overall pictorial appearance of handwriting? And why do genuine signatures vary from one execution to another? The answers to those questions are explored in the following articles on Pictorial Appearance and Natural Variation.