What is forensic psychology?

Hugo Münsterberg, answered from the texts and cited to the page.

Hugo Münsterberg answers

Forensic psychology is, at its core, the application of the science of the mind to the purposes of justice — the carrying of the laboratory into the courtroom, so that what the psychologist has learned about perception, memory, attention, suggestion, and emotion may bear on the great practical questions the law must decide. The law has long known how to guard against the deliberate liar.

What it has scarcely begun to reckon with is the honest witness who errs. Consider how many points of failure stand between an event and its faithful report in court. The original sensory perception may have been defective; the apprehension at the moment of perception may have been erroneous; the memory trace may have changed in the interval so that correct reproduction has become impossible; the will to reproduce may not have been strong enough to resist suggestion; and the witness may have lacked the very words to express what he did retain.1

Only if the process runs clear at every one of these points can testimony count as an objective report — and in practice, it rarely does. Beyond the honest witness, there is the question of the accused who will not speak, and the older, brutal methods that were once used to compel confession. Exhaustion, hunger, fear of punishment, and the emotion of uncertainty reduce the resistance of the will and create a state of heightened suggestibility, so that monotonous words and encouraging confidential talk may cause the controlling idea of truth to discharge itself in confession.2

The laboratory offers something far more precise: the measurement of involuntary emotional expression — the galvanometer recording the fluctuation of galvanic skin response, the pneumograph tracing feeling's influence on respiration, the sphygmograph reading the pulse with microscopic exactitude.3 Where the jury notices a man tremble or blush, the instruments catch what no ordinary observer would see.

And there is the detection of concealed knowledge through the study of associations. The chronoscope of the modern psychologist stands to the student of crime as the microscope stands to the student of disease — it makes visible what remains otherwise invisible, and shows minute facts that allow a clear diagnosis.4 A physician needs his magnifier to find tubercles in the sputum; the legal psychologist may use his mental microscope to make sure whether there are lies in the mind of the suspect.5

None of this displaces the judge or the jury. The psychologist's role is the more modest and the more indispensable one: to tell the court what the mind can and cannot faithfully report. The law ignores this at the cost of justice. No railroad company would appoint to a responsible post a man whose eyesight had not been tested for color blindness — one man in thirty or forty who cannot distinguish the red lantern from the green may wreck two trains.6

In the life of justice, trains are wrecked and ships collide too often, simply because the law does not care to examine the mental color blindness of the witness's memory.7 Forensic psychology is the science that tests the eyesight before the appointment is made.

Sources

  1. It is possible that the original sensory perception was defective; or, secondly, that the apprehension at the time of the perception was erroneous. Thirdly, the disposition for the memory images may have changed in the course of time so that a correct reproduction has become impossible. Fourthly, the will to reproduce the memory ideas may not have been intense enough to overcome suggestions or autosuggestions or to secure completeness. Finally, the witness may have lacked the ability to express his ideas correctly.
    Psychology General and Applied
  2. The exhaustion from sleepless nights and hunger, the fear of punishment, and the emotion of uncertainty greatly reduce the resistance of the will, and thus create a state of increased suggestibility. If monotonous words, encouraging confidential talks and uniform sense impressions are added, the resistance crumbles, and the controlling idea of the truth discharges itself in confessions.
    Psychology General and Applied
  3. Sphygmographic records of the influence of inner excitement on the pulse can tell with microscopic exactitude what the tears in the eyes or the trembling or the hasty breathing or the stammering speech show superficially.
    Psychology General and Applied
  4. The chronoscope of the modern psychologist has become, and will become more and more, for the student of crime what the microscope is for the student of disease. It makes visible that which remains otherwise invisible, and shows minute facts which allow a clear diagnosis.
    On the Witness Stand
  5. The physician needs his magnifier to find out whether there are tubercles in the sputum: the legal psychologist may in the future use his mental microscope to make sure whether there are lies in the mind of the suspect.
    On the Witness Stand
  6. No railroad or ship company would appoint to a responsible post in its service men whose eyesight had not been tested for colour blindness. There may be only one among thirty or forty who cannot distinguish at a distance the red from the green lantern.
    On the Witness Stand
  7. In the life of justice trains are wrecked and ships are colliding too often, simply because the law does not care to examine the mental colour blindness of the witness's memory.
    On the Witness Stand