Abstract
To
evaluate the applicability of the guilty knowledge technique,
758 polygraph examination cases were surveyed for operable
case facts (keys). Polygraph examiners and Special Agents
assigned to 25 FBI field divisions provided the case information.
The 95% confidence interval for guilty knowledge technique
applicability in criminal investigations was 5.0% to 8.6%.
The guilty knowledge technique was inapplicable where contextual
limitations precluded keys (85.0%), where potential keys had
been revealed (4.4%), and where the number of potential keys
was insufficient (one or two, 4.0%). Although its applicability
in FBI criminal investigations is restricted, the guilty knowledge
technique could be applied to a small proportion of examinations.
Introduction
Lykken (1988b p. 303) asserted that "one
of the most accurate and socially useful of psychological
tests [the guilty knowledge test/technique (GKT) for deception
detection] is being arbitrarily neglected." Others agreed,
presenting the guilty knowledge technique as a superior alternative
to present methods (Ben-Shakhar 1991; Ben-Shakhar and Furedy
1990; Furedy 1993; Furedy and Heslegrave 1991; Iacono and
Patrick 1987; Kleinmuntz and Szucko 1982; see also Lykken,
1981, 1991, 1992).
Indeed, the guilty knowledge technique is appealing. Described
by Benjamin Burack (1955, p. 416) and adopted by Lykken (1959),
the guilty knowledge technique is based on the plausible assumption
that guilty, but not innocent, subjects will produce their
largest physiological reactions to undisclosed case details
(keys) presented among incorrect, but plausible, alternatives.
The guilty knowledge technique has consistently demonstrated
criterion validity in categorizing innocent and guilty roles
of subjects in simulated crimes (e.g., Bradley and Rettinger
1992; Davidson 1968; Iacono et al. 1984; Iacono et al. 1992;
Lykken 1959; Podlesny and Raskin 1978).
Lykken (1988b) attributed neglect of the guilty knowledge
technique to the "belief that appropriate GKT items [keys]
could not be designed in the field situation" (p. 303),
an assumption that he considered "overly pessimistic
in most specific-issue situations in which polygraphic interrogation
might be contemplated (p. 304). At the time, it was
not known whether keys would be available in real-life contexts,
since there was a lack of empirical information. Others claimed
that there are practical limitations on the availability of
keys (Abrams 1975; Forman and McCauley 1986; Kircher and Raskin
1992; Podlesny and Raskin 1978; Raskin 1988, 1989; Raskin
and Kircher 1991; Rosenfeld 1995). Presumed impediments were
the legitimate access of many suspects to case details; the
release of case information through investigative interviews,
the media, or legal discovery; and the possible failure of
guilty suspects to notice or remember details of their crimes.
There have been few studies pertinent to the applicability
of the guilty knowledge technique. For Israeli examinations
in which guilty knowledge techniques had been used, Elaad
(1990) and Elaad, Ginton, and Jungman (1992) reported that
the number of keys per examination ranged from one to six
and averaged 2.0 and 1.8, respectively. Those reports did
not enumerate cases in which guilty knowledge techniques were
not used because no keys were available. Podlesny (1993) reviewed
61 criminal examinations and found that four or more apparently
usable keys appeared in the case records for eight (13.1%)
of the examinations. In that study, 45 of the 61 examinees
(73.8%) had legitimate access to the case details. However,
the case information was obtained entirely from records, and
the sample was small and selective.
More reliable facts are needed to determine the extent to
which sufficient, operable (usable) keys are available to
support the application of the guilty knowledge technique.
The present study estimates the availability of keys in FBI
criminal cases in which deception detection examinations are
used. Case information related to 758 examinations was collected
from FBI field offices throughout the United States. The results
indicate that sufficient keys are likely to be available in
about 5.0% to 8.6% of FBI criminal examinations and that most
examinations are intractable to the guilty knowledge technique
for explicit reasons.
Method
Polygraph examiners from 25 FBI field offices
collected case data for each criminal examination assigned
to them from November 1, 1993, through August 31, 1994, a
total of 758 examinations. The examiners collected the data
while preparing for the examinations and provided the data
after the examinations were complete (they did not conduct
any guilty knowledge tests). The sample comprised 35.6% of
the criminal examinations conducted by the FBI during that
period (2131), (Table
1). The examiners received written and verbal instructions
about the survey goals, methods for identifying keys, sources
of information, and procedures for reporting data.
Table
1. |
Participating
FBI Field Divisions
and the Number of Submitted Reports |
Atlanta,
Georgia
|
Birmingham,
Alabama |
Boston,
Massachusetts |
Charlotte,
North Carolina |
Chicago,
Illinois |
Cleveland,
Ohio |
Dallas,
Texas |
Detroit,
Michigan |
Kansas
City, Missouri |
Knoxville,
Tennessee |
Los
Angeles, California |
Louisville,
Kentucky |
Memphis,
Tennessee |
Miami,
Florida |
Minneapolis,
Minnesota |
Newark,
New Jersey |
New
York, New York |
Oklahoma
City, Oklahoma |
Omaha,
Nebraska |
Philadelphia,
Pennsylvania |
Phoenix,
Arizona |
Portland,
Oregon |
San
Antonio, Texas |
San
Francisco, California |
Washington,
DC |
|
51 |
23 |
30 |
37 |
32 |
42 |
8 |
50 |
45 |
10 |
31 |
14 |
23 |
21 |
29 |
11 |
19 |
40 |
33 |
24 |
37 |
23 |
30 |
48 |
47 |
|
|
|
A potential key was defined as a specific case fact that would
likely be known to guilty person(s); that, if not revealed,
would likely not be known to innocent persons; and for which
it was believed at least a few plausible alternatives could
be listed (Burack 1955; Lykken 1959, 1974). An operable key
was a potential key that had not been revealed outside the investigation
and was, therefore, assumed to be usable in a guilty knowledge
test. To identify potential keys, the examiners queried all
available sources of information including case officials, case
records, and media reports. For each examination, the examiner
provided a case summary, the purpose of the examination, and
a list of potential keys. Where there were no potential keys,
the examiner provided an explanation. Where potential keys had
been revealed, the examiner provided a list of those keys with
an explanation concerning their release.
The reports were reviewed for completeness and intelligibility.
In those instances where further information was needed, an
assistant interviewed the examiner. The revised information
was then reviewed and, as required, the examiners and case Agents
were interviewed by the author. The case Agents were the investigators
who requested the examinations. Data collection continued in
each instance until all apparent keys were identified or a cogent
explanation was obtained for a lack of keys. This process produced
a database containing the revised data from the original reports
and the interviews.
Results
In the case information related to the 758 examinations,
there were 587 potential keys. Of these, 232 had been revealed,
either through the news media or during interviews of the examinees.
Thus, there were 355 operable keys, an average of 0.47 operable
keys per examination request.
Table
2. |
Distribution
of the Examination Cases by the Number
of Potential and Operable Keys Found |
|
Potential
Keys
|
Frequency
|
|
(Percent)
|
|
Operable
Keys
|
Frequency
|
|
(Percent)
|
|
|
Six
or more
|
Five
|
Four
|
Three
|
Two
|
One
|
None
|
|
35
|
|
(4.6)
|
|
18
|
|
(2.4)
|
|
15
|
|
(2.0)
|
|
16
|
|
(2.1)
|
|
13
|
|
(1.7)
|
|
17
|
|
(2.2)
|
|
644
|
|
(85.0)
|
|
|
16
|
|
(2.1)
|
|
9
|
|
(1.2)
|
|
10
|
|
(1.3)
|
|
16
|
|
(2.1)
|
|
10
|
|
(1.3)
|
|
21
|
|
(2.8)
|
|
676
|
|
(89.2)
|
|
|
|
|
|
Table
2 shows the distribution of the examination cases by the
number of potential and operable keys found. It was necessary
to select a criterion in order to decide whether the guilty
knowledge technique would have been applicable to any given
examination. Lykken (1988b) recommended that six or more keys
should be used, claiming that this would be possible in "many
criminal investigations...with a little effort and imagination"
(p. 304). Six or more keys would provide strong protection against
chance false-positive errors. By Lykken's criterion, the best
estimate for applicability was 2.1% (16 of 758 examinations).
A more lenient criterion of at least three operable keys may
be considered minimally sufficient (Forman and McCauley 1986).
Assuming three operable keys and four incorrect alternatives
per key, the binomial probability that the largest physiological
reactions would occur by chance in response to two or three
of the keys is .10. In the context of an investigation, this
might be sufficient to provide direction to investigators. By
this criterion, there were 51 (6.7%) examinations to which the
guilty knowledge technique could have been applied. A resampling
procedure (Diaconis and Efron 1983; Efron and Tibshirani 1991;
Simon and Bruce 1991) produced a 95% confidence interval of
5.0% to 8.6% for guilty knowledge technique applicability to
FBI criminal examinations for the latter (lenient) criterion.
This estimate, produced as follows, assumes that the present
sample is representative of FBI criminal investigations in which
examinations are conducted. Fifteen thousand samples each of
n = 758 were drawn at random with replacement from the integers
1 through 758 (total examinations). A count of the occurrences
of 51 integers (1 through 51, the number of guilty knowledge
technique-applicable examinations in the sample) was obtained
for each sample. The 95% confidence interval of 5.0% to 8.6%
was obtained from the distribution of counts for the 15,000
samples.
The guilty knowledge technique was inapplicable to 707 of the
examination cases (93.3%). There were 33 examinations (4.4%)
with three or more potential keys, but less than three operable
keys because some keys had been revealed. There were 30 examination
cases (4.0%) with only one or two potential keys. There were
644 examination cases (85.0%) with no potential keys. The case
circumstances in which keys were lacking in those cases is as
follows:
1. |
The
examinee had legitimate reason for access to the case
information (281, 37.1%). Examples were cases in which
bank tellers, armored-car personnel, or other employees,
who had direct access to business activities and conversations
with coworkers, were suspected of internal thefts.
|
2. |
The
examinee was the source of information requiring verification
(152, 20.1%). Examples were cases in which there was a
need to verify the statements of sources or allegers in
the absence of factual information.
|
3. |
A
violation was suspected only on the basis of allegations
(90, 11.9%). Examples were cases in which individuals
were suspected of child molestation or bribery, based
on the allegations of other individual(s) in the absence
of factual information.
|
4. |
The
examinee admitted involvement, but denied any intention
to commit a violation (29, 3.8%). Examples were cases
in which individuals admitted fraudulent activities, but
claimed they had not known that those activities were
illegal.
|
5. |
It
was unknown whether a violation had actually occurred,
and the examination was based on the suspicions of investigators
(19, 2.5%). Examples were cases in which individuals pleaded
guilty to drug violations and were suspected of having
engaged in other unspecified illegal activities or of
withholding information about recoverable assets.
|
6. |
There
was a lack of factual case information for various reasons
(8, 1.1%). An example was a case in which a former bank
teller was suspected in the theft of an indefinite amount
of money that had disappeared mysteriously.
|
7. |
Various
combinations of the above (65, 8.6%). |
Over half of the 51 guilty knowledge technique-applicable examinations
were in cases of bank robbery (19) or kidnapping (10). The proportions
of the sample totals for those case types were 25.0% and 17.2%,
respectively. Post hoc-resampling procedures (similar to the
above) produced 95% confidence intervals of 15.8% to 35.5% for
bank robberies and 8.6% to 27.6% for kidnappings. Thus, guilty
knowledge techniques were more applicable in bank robberies
and kidnappings than in the general sample (5.0% to 8.6%).
Discussion
The results are consistent with previous studies
indicating a paucity of operable keys in practice (Elaad 1990;
Elaad et al. 1992; Podlesny 1993). The present survey provides
more reliable estimates than those studies because the sample
is large, because it contains information from all available
case resources, including examiners, investigators, records,
and news media, and because examinations were not selected on
the basis that guilty knowledge techniques had been used, as
in the studies of Elaad and coworkers (1990, 1992). Although
many favorable comments on the applicability of the guilty knowledge
technique have appeared (cited above), these have not yet been
supported by facts.
Lykken (1974, p. 728) suggested that "...the guilty knowledge
method simply cannot be used in many situations in which the
lie detector is now used..." The present empirical estimate
indicates that the guilty knowledge technique cannot be used
in the large majority of FBI criminal investigations in which
deception detection is used. Furthermore, where there were no
potential keys (85.0% of the sample), this was attributable
to contextual limitations of the cases rather than to insufficient
preparation or "effort and imagination" (Lykken 1988b
p. 304). It does not appear that the guilty knowledge technique
has been "arbitrarily neglected" (Lykken 1988b p.
303); rather, it is likely that the GKT has not been used because
it is rarely applicable.
Implications
for Practice
In consideration of restricted applicability,
the guilty knowledge technique is not a general alternative
to direct-questioning methods, which are the standard of practice
(as suggested by Ben-Shakhar 1991; Ben-Shakhar and Furedy 1990;
Furedy and Heslegrave 1991; Iacono and Patrick 1987; Kleinmuntz
and Szucko 1982; Lykken 1981, 1988a, 1991). Direct-questioning
methods, such as control-question tests, do not require operable
keys.
|
|
Prior
to the introduction
of guilty knowledge techniques,
there is a need to establish
scientific standards
for selecting operable keys,
selecting alternative stimuli,
structuring and presenting tests,
and interpreting tests. |
|
|
Because
sufficient operable keys are available relative to a small proportion
of examinations, there is unrealized potential for applying
guilty knowledge techniques in some instances. Where applicable,
guilty knowledge techniques might be introduced as a supplement
to other methods, possibly adding protection against false positives
(Iacono and Patrick 1987) or as a primary means for demonstrating
probable connections between guilty individuals and violations.
It may be possible to increase the proportion of guilty knowledge
technique-applicable examinations by a few percent through stronger
controls on the unnecessary release of case information. However,
in practice, it is often necessary to release information in
order to apprehend perpetrators and locate victims (e.g., clothing
worn by bank robbers and kidnapping victims). Prior to the introduction
of guilty knowledge techniques, there is a need to establish
scientific standards for selecting operable keys, selecting
alternative stimuli, structuring and presenting tests, and interpreting
tests.
Limitations
The examiners who provided much of the case information
used in this study normally practiced direct questioning methods.
Thus, it may be suggested that the examiners, knowing the purpose
of the study, would have favored the finding that keys were
lacking. However, the examiners were not unfamiliar with the
use of case facts in examinations, since they were trained with
the peak of tension test, a technique that similarly
depends on operable case facts and differs in test format from
the guilty knowledge technique. Further, the study procedure
of collecting a summary of each case, a statement of the purpose
of each examination requested, and a cogent explanation in each
case where keys were reportedly lacking tends to counteract
bias. It was not sufficient for an examiner to report only that
there were no keys. This procedure made it possible to provide
a circumstantial categorization and enumeration of cases in
which keys were lacking (above). The reader may wish to consider
how it could be possible to formulate operable keys in each
of the seven categories of case circumstances described in the
Results. Finally, exhaustive efforts were made to identify potential
and operable keys wherever possible. In instances where it seemed
that keys might have been overlooked, the author interviewed
the case Agents; the case Agents were not examiners and had
no apparent commitment to any polygraph technique.
Because the sample included only cases in which polygraph examinations
were conducted in FBI criminal investigations, the results may
not generalize to other contexts. Guilty knowledge techniques
could be either more or less applicable to investigations in
other jurisdictions with differently distributed caseloads.
For example, burglaries, usually investigated locally, may be
productive of keys based on the methods of entry and specific
items taken. The results also do not necessarily generalize
to FBI criminal investigations where examinations are not requested.
Judging by the reasons for the lack of keys (above), the FBI
frequently employs polygraph examinations to provide direction
to ambiguous investigations. It is possible that guilty knowledge
techniques might be more applicable in cases where better evidence
generates potential keys; however, in those cases there may
be less need for examinations.
Informed decisions concerning introduction of the guilty knowledge
technique require information on validity as well as applicability.
The results do not provide information on the validity of guilty
knowledge techniques or any other deception detection method(s).
Further
Research
This study provides an estimate of guilty knowledge
technique applicability where deception detection examinations
are requested in FBI criminal investigations. There is a lack
of research regarding the applicability of guilty knowledge
techniques in other law enforcement contexts, such as state
or local investigations or those of other federal agencies.
Research might also address applicability to investigations
in which examinations are not presently requested. The results
indicate that attempts to identify applicable cases may, at
least occasionally, be successful; however, anecdotal case reports
(Lykken 1981, pp. 257-296) are not sufficient to provide estimates
of applicability. Appropriate sampling schemes and full reporting
of both applicable and inapplicable instances are required for
such estimates.
Laboratory studies, contrived to have adequate numbers of operable
keys, have consistently demonstrated the validity of guilty
knowledge techniques (citations above); but the field validity
studies produced large proportions of false negatives (Elaad
1990; Elaad et al. 1992). Those authors suggested that the small
average number of keys (2.0 and 1.8, respectively) may have
contributed to the false-negative rates. It appears that the
guilty knowledge tests had frequently been used in cases where
they were inapplicable. Field-validity research on cases with
sufficient operable keys would provide more reliable estimates
of field validity. Elaad, Ginton, and Jungman (1992, p. 765)
suggested that "...some guilty examinees do not notice
or remember all the facts of the crime available to the investigator."
The likelihood a guilty person will recognize case details may
be affected by the passage of time, the examinee's characteristic
interests, active versus passive acquisition, advance preparation
versus incidental contact, other similar violations remembered
or planned by the examinee, and the distinctness of keys and
alternatives (Elaad 1990). Research on such factors could clarify
the requirements for valid operable keys and alternative stimuli.
The findings evidence both restrictions on and opportunities
for application of the guilty knowledge technique. Applicability
to FBI investigations is restricted; as a consequence, direct-questioning
methods are advantageous where applicability is concerned. Nevertheless,
the guilty knowledge technique is applicable to some examinations,
and practitioners may wish to consider the utility of guilty
knowledge techniques in cases where sufficient operable keys
do exist.
Acknowledgments
The author is grateful for the assistance of
the FBI polygraph examiners who provided the case reports for
this research: Claude T. Adams; Ronald L. Clenney; Clifford
Cormany, Jr.; Frank A. Cryan; Lester L. Davis, Jr.; Thomas F.
Donlan, III; Robert J. Drdak; Salvador R. Escobedo; Edward T.
Hamara; Michael Hanna; William C. Holloman; Ronald R. Homer;
Mark R. Johnson; Walton G. Jones; James E. Judd; Stephen T.
Kives; W. Ronald Lilly; H. Hadley McCann, Jr.; Michael A. McCrery;
Blaine D. McIlwaine; Robert H. Meredith; Leonard J. Michaud;
Michael R. Napier; Donald W. Ramsey; Robert E. Reich, Jr.; Arthur
G. Richards, Jr.; William K. Teigen; John R. Trimarco; and Donald
E. Wright. Debrah L. Hauger assisted with data collection. Colleen
Wade and Tonya L. Catterton assisted with the preparation of
the manuscript. Francis T. Morgovnik provided administrative
assistance.
References
Abrams, S.
A response to Lykken on the polygraph, American Psychologist
(1975) 30(6):709-711.
Ben-Shakhar, G. Future prospects of psychophysiological detection:
Replacing the CQT by the GKT. In: Advances in Psychophysiology,
Volume 4. J. R. Jennings, P. K. Ackles, and M. G. H. Coles,
eds. Jessica Kingsley, London, 1991, pp. 193-199.
Ben-Shakhar, G. and Furedy, J. J. Theories and Applications
in the Detection of Deception: A Psychophysiological and International
Perspective. Springer-Verlag, New York, 1990.
Bradley, M. T. and Rettinger, J. Awareness of crime-relevant
information and the guilty knowledge test, Journal of Applied
Psychology (1992) 77(1):55-59.
Burack, B. A critical analysis of the theory, method, and limitations
of the "lie detector," Journal of Criminal Law,
Criminology and Police Science (1955) 46:414-426.
Davidson, P. O. Validity of the guilty-knowledge technique:
The effects of motivation, Journal of Applied Psychology
(1968) 52(1):62-65.
Diaconis, P. and Efron, B. Computer-intensive methods in statistics,
Scientific American (1983) 248(5):116-130.
Efron, B. and Tibshirani, R. Statistical data analysis in the
computer age, Science (1991) 253: 390-395.
Elaad, E. Detection of guilty knowledge in real-life criminal
investigations, Journal of Applied Psychology (1990)
75(5):521-529.
Elaad, E., Ginton, A., and Jungman, N. Detection measures in
real-life criminal guilty knowledge tests, Journal of Applied
Psychology (1992) 77(5):757-767.
Forman, R. F. and McCauley, C. Validity of the positive control
polygraph test using the field practice model, Journal of
Applied Psychology (1986) 71(4):691-698.
Furedy, J. J. The "control" question "test"
(CQT) polygrapher's dilemma: Logico-ethical considerations for
psychophysiological practitioners and researchers, International
Journal of Psychophysiology (1993) 15:263-267.
Furedy, J. J. and Heslegrave, R. J. The forensic use of the
polygraph: A psychophysiological analysis of current trends
and future prospects. In: Advances in Psychophysiology,
Volume 4. J. R. Jennings, P. K. Ackles, and M. G. H. Coles,
eds. Jessica Kingsley, London, 1991, pp. 157-189.
Iacono, W. G., Boisvenu, G. A., and Fleming, J. A. Effects of
diazepam and methylphenidate on the electrodermal detection
of guilty knowledge, Journal of Applied Psychology (1984)
69(2):289-299.
Iacono, W. G., Cerri, A. M., Patrick, C. J., and Fleming, J.
A. E. Use of antianxiety drugs as countermeasures in the detection
of guilty knowledge, Journal of Applied Psychology (1992)
77(1):60-64.
Iacono, W. G. and Patrick, C. J. What psychologists should know
about lie detection. In: Handbook of Forensic Psychology.
I. B. Weiner and A. K. Hess, eds. Wiley, New York, 1987, pp
460-489.
Kircher, J. C. and Raskin, D. C. Polygraph techniques: History,
controversies, and prospects. In: Psychology and Social Policy.
P. Suedfeld and P. E. Tetlock, eds. Hemisphere, New York, 1992,
pp. 295-307.
Kleinmuntz, B. and Szucko, J. J. On the fallibility of lie detection,
Law and Society Review (1982) 17(1):85-104.
Lykken, D. T. The GSR in the detection of guilt, Journal
of Applied Psychology (1959) 43(6):385-388.
Lykken, D. T. Psychology and the lie detector industry, American
Psychologist (1974) 29(10):725-739.
Lykken, D. T. A Tremor in the Blood: Uses and Abuses of the
Lie Detector. McGraw-Hill, New York, 1981.
Lykken, D. T. The case against polygraph testing. In: The
Polygraph Test: Lies, Truth and Science. A. Gale, ed. Sage,
London, 1988a pp. 111-125.
Lykken, D. T. Detection of guilty knowledge: A comment on Forman
and McCauley, Journal of Applied Psychology (1988b) 73(2):303-304.
Lykken, D. T. The lie detector controversy: An alternative solution.
In: Advances in Psychophysiology, Volume 4. J. R. Jennings,
P. K. Ackles, and M. G. H. Coles, eds. Jessica Kingsley, London,
1991, PP 209-214.
Lykken, D. T. Controversy: The fight-or-flight response in homo
scientificus. In: Psychology and Social Policy. P. Suedfeld
and P. E. Tetlock, eds. Hemisphere, New York, 1992, pp. 309-325.
Podlesny, J. A. Is the guilty knowledge polygraph technique
applicable in criminal investigations? A review of FBI case
records, Crime Laboratory Digest (1993) 20(3):57-61.
Podlesny, J. A. and Raskin, D. C. Effectiveness of techniques
and physiological measures in the detection of deception, Psychophysiology
(1978) 15(4):344-359.
Raskin, D. C. Does science support polygraph testing? In: The
Polygraph Test: Lies, Truth and Science. A. Gale, ed. Sage,
London, 1988, pp. 96-110.
Raskin, D. C. Polygraph techniques for the detection of deception.
In: Psychological Methods in Criminal Investigation and Evidence.
D. C. Raskin, ed. Springer, New York, 1989, pp. 247-296.
Raskin, D. C. and Kircher, J. C. Comments on Furedy and Heslegrave:
Misconceptions, misdescriptions, and misdirections. In: Advances
in Psychophysiology, Volume 4. J. R. Jennings, P. K. Ackles,
and M. G. H. Coles, eds. Jessica Kingsley, London, 1991, pp.
215-223.
Rosenfeld, J. P. Alternative views of Bashore and Rapp's (1993)
alternatives to traditional polygraphy: A critique, Psychological
Bulletin (1995) 117(1):159-166.
Simon, J. L. and Bruce, P. Resampling: A tool for everyday statistical
work, Chance (1991) 4(1): 22-32.
|