The Observations. Although you cannot control the technique of observation by
other persons, you may, through skillful and patient questioning, often aid them in
recalling details observed.
Thus, while the witness may not be trained or
experienced in observing, it may be possible for you to develop a reasonably clear
word picture of what they observed by encouraging the use of a pattern of recall.
When thus encouraged to recall in a methodical fashion that which he observed, a
witness may realize that he saw much more than he recorded at the time of
observation. Before you can obtain and develop the descriptions of other persons,
you must acquire an awareness of, and be able to make allowances for, the facts
which influence perception, interpretation, and retention.
a. External Influences.
(1) Location of the Witness at Time of Observation.
Two or more persons
will seldom have witnessed an incident from exactly the same location.
may account for differences in observations.
(2) Weather and Light Conditions.
The effects of weather and light upon
observations are self-evident. You must make proper allowance for them.
(3) Presence of Distracting Events.
Unrelated events may influence a
witness' observation of a particular incident.
Thus, an exciting play on a
football field may cause a spectator to fail to observe what the person sitting
next to him is doing.
(4) Lapse of Time Since the Observation was Made.
The passage of time
between observation and recall can influence a description. The imaginative person
may tend to fill in the gaps in his knowledge if he has learned that the incident
is important in an investigation.
On the other hand, many persons will tend to
forget or confuse details with the passage of time. It is important that witnesses
and victims be interviewed as soon as possible after they made their observation
and before they had time to adjust their observations to fit the pattern of other
information they may have seen or heard.
b. Human Factors.
Perception is largely determined and influenced by past
experiences, physiological and psychological influences, and training. Within this
framework, a person evaluates and interprets through the five senses. The special
evaluate their effects upon the observations of a witness or victim.
(1) Past Experiences.
The person's evaluation and interpretation of that
which he observes tends to be predetermined by his past experience of similar or
The size of an object could be compared with the size of
another object with which he is familiar.
Familiar sounds, odors, tastes, and
Incoming stimuli with which
there are not past comparable perceptions will often be misinterpreted in terms of
familiar things. In general, you should bear in mind that: