“I know what I saw.” “That’s not the
way it happened.”
Witnesses can be convincing, consistent,
clear—and wrong. Most trial lawyers have
dealt with contradictory testimony or wit-
ness explanations contrary to the laws of
physics. Why? While some of this may be
attributed to dishonesty or self-serving
motivations, it turns out it is easier to fool
the human brain than one might think.
The triers of fact are often faced
with contradictory lay witness statements.
Expert witnesses, in attempting to recreate
an event scenario, are often challenged as
to why one witness’s testimony is viewed
superior to that of another witness.
The lay witness will incorporate stimuli
during the event with their experiences and
knowledge base. Visual, audible, olfactory
and even tactile clues will be used by the
brain, and a “story” will be developed. The
story that one puts together must be consistent with one’s experiences before the
event. However, the story may not be consistent with the known facts of the case—or
even with the laws of nature.
In one recent case, an injured young
woman testified convincingly that an
explosion occurred when she reached into
a recessed area to turn a switch to the OFF
position. However, as the first responders
documented upon arrival, not only was
that switch still in the ON position, but the
appliance (a fireplace) was still running.
What had actually happened is that the
young woman ignited leaking gas when she
used a cigarette lighter to check for spiders.
The deactivation of the switch required
a series of actions that she had done before
and that she had every intention of doing
again. On that day, she did not get to the
switch. However, the processes by which
humans convert memory from short term
to long term were interrupted. Falling back
on her experiences, she was sure that on
that day, as on others, she had toggled the
From this point, one can begin to see
how witnesses can get things wrong. We fill
in what we expect to see, not necessarily
what is real. There are numerous experiments that have demonstrated this.
Examples include two researchers holding
an imaginary string across a busy sidewalk.
While there is no string visible, people can
be seen jumping to avoid the perceived haz-
ard. This is true even if people immediately
preceding them pass through without jump-
ing and without encountering anything but
imaginary string. There must be a string
there, right? Why didn’t the other guy trip?
DAVID S. KOMM, PE, PEng, CFEI, is the
President of Augspurger Komm Engineering,
Inc. & BTI Consultants, Phoenix.
BY DAVID S. KOMM we Believe