Impact crater

In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body. In most common usage, the term is used for the approximately circular depression in the surface of a planet, moon or other solid body in the Solar System, formed by the hypervelocity impact of a smaller body with the surface. In contrast to volcanic craters, which result from explosion or internal collapse^[1], impact craters typically have raised rims and floors that are lower in elevation than the surrounding terrain^[2]. Impact craters range from small, simple, bowl-shaped depressions to large, complex, multi-ringed impact basins. Meteor Crater is perhaps the best-known example of a small impact crater on the Earth.
Impact craters are the dominant landforms on many solid Solar System objects including the Moon, Mercury, Callisto, Ganymede and most small moons and asteroids. On other planets and moons that experience more-active surface geological processes, such as Earth, Venus, Mars, Europa, Io and Titan, visible impact craters are less common because they become eroded, buried or transformed by tectonics over time. Where such processes have destroyed most of the original crater topography, the terms impact structure or astrobleme are more commonly used. In early literature, before the significance of impact cratering was widely recognised, the terms cryptoexplosion or cryptovolcanic structure were often used to describe what are now recognised as impact-related features on Earth^[3].
In the early Solar System, rates of impact cratering were much higher than today. The large multi-ringed impact basins, with diameters of hundreds of kilometers or more, retained for example on Mercury and the Moon, record a period of intense early bombardment in the inner Solar System that ended about 3.8 billion years ago. Since that time, the rate of crater production on Earth has been considerably lower, but it is appreciable nonetheless; Earth experiences from one to three impacts large enough to produce a 20 km diameter crater about once every million years on average^[4][5]. This indicates that there should be far more relatively young craters on the planet than have been discovered so far.
Although the Earth’s active surface processes quickly destroy the impact record, about 170 terrestrial impact craters have been identified^[6]. These range in diameter from a few tens of meters up to about 300 km, and they range in age from recent times (e.g. the Sikhote-Alin craters in Russia whose creation were witnessed in 1947) to more than two billion years, though most are less than 500 million years old because geological processes tend to obliterate older craters. They are also selectively found in the stable interior regions of continents^[7]. Few undersea craters have been discovered because of the difficulty of surveying the sea floor, the rapid rate of change of the ocean bottom, and the subduction of the ocean floor into the Earth's interior by processes of plate tectonics.
Impact craters are not to be confused with other landforms that in some cases appear similar, including calderas and ring dikes.

The prominent impact crater Tycho on the Moon. NASA photo.

 

History

Eugene Shoemaker, pioneer impact crater researcher, here at a stereoscopic microscope used for asteroid discovery

Daniel Barringer (1860–1929) was one of the first to identify an impact crater, Meteor Crater in Arizona; to crater specialists the site is referred to as Barringer Crater in his honor. Initially Barringer's ideas were not widely accepted, and even when the origin of Meteor Crater was finally acknowledged, the wider implications for impact cratering as a significant geological process on Earth were not.
In the 1920s, the American geologist Walter H. Bucher studied a number of sites now recognized as impact craters in the USA. He concluded they had been created by some great explosive event, but believed that this force was probably volcanic in origin. However, in 1936, the geologists John D. Boon and Claude C. Albritton Jr. revisited Bucher's studies and concluded that the craters that he studied were probably formed by impacts.
The concept of impact cratering remained more or less speculative until the 1960s. At this time a number of researchers, most notably Eugene M. Shoemaker, (co-discoverer of the comet Shoemaker-Levy 9), conducted detailed studies of a number of craters and recognized clear evidence that they had been created by impacts, specifically identifying the shock-metamorphic effects uniquely associated with impact events, of which the most familiar is shocked quartz.
Armed with the knowledge of shock-metamorphic features, Carlyle S. Beals and colleagues at the Dominion Observatory in Victoria, British Columbia, Canada and Wolf von Engelhardt of the University of Tübingen in Germany began a methodical search for impact craters. By 1970, they had tentatively identified more than 50. Although their work was controversial, the American Apollo Moon landings, which were in progress at the time, provided supportive evidence by recognizing the rate of impact cratering on the Moon^[8]. Processes of erosion on the Moon are minimal and so craters persist almost indefinitely. Since the Earth could be expected to have roughly the same cratering rate as the Moon, it became clear that the Earth had suffered far more impacts than could be seen by counting evident craters.

[edit] Crater formation

A laboratory simulation of an impact event and crater formation

Impact cratering involves high velocity collisions between solid objects, typically much greater than the velocity of sound in those objects. Such hyper-velocity impacts produce physical effects such as melting and vaporization that do not occur in familiar sub-sonic collisions. On Earth, ignoring the slowing effects of travel through the atmosphere, the lowest impact velocity with an object from space is equal to the gravitational escape velocity of about 11 km/s. The fastest impacts occur at more than 70 km/s, calculated by summing the escape velocity from Earth, the escape velocity from the Sun at the Earth's orbit, and the motion of the Earth around the Sun. The median impact velocity on Earth is about 20 to 25 km/s.
Impacts at these high speeds produce shock waves in solid materials, and both impactor and the material impacted are rapidly compressed to high density. Following initial compression, the high-density, over-compressed region rapidly depressurizes, exploding violently, to set in train the sequence of events that produces the impact crater. Impact-crater formation is therefore more closely analogous to cratering by high explosives than by mechanical displacement. Indeed, the energy density of some material involved in the formation of impact craters is many times higher than that generated by high explosives. Since craters are caused by explosions, they are nearly always circular – only very low-angle impacts cause significantly elliptical craters.
It is convenient to divide the impact process conceptually into three distinct stages: (1) initial contact and compression, (2) excavation, (3) modification and collapse. In practice, there is overlap between the three processes with, for example, the excavation of the crater continuing in some regions while modification and collapse is already underway in others.

[edit] Contact and compression

In the absence of atmosphere, the impact process begins when the impactor first touches the target surface. This contact accelerates the target and decelerates the impactor. Because the impactor is moving so rapidly, the rear of the object moves a significant distance during the short-but-finite time taken for the deceleration to propagate across the impactor. As a result, the impactor is compressed, its density rises, and the pressure within it increases dramatically. Peak pressures in large impacts exceed 1 TPa to reach values more usually found deep in the interiors of planets, or generated artificially in nuclear explosions.
In physical terms, a supersonic shock wave initiates from the point of contact. As this shock wave expands, it decelerates and compresses the impactor, and it accelerates and compresses the target. Stress levels within the shock wave far exceed the strength of solid materials; consequently, both the impactor and the target close to the impact site are irreversibly damaged. Many crystalline minerals can be transformed into higher-density phases by shock waves; for example, the common mineral quartz can be transformed into the higher-pressure forms coesite and stishovite. Many other shock-related changes take place within both impactor and target as the shock wave passes through, and some of these changes can be used as diagnostic tools to determine whether particular geological features were produced by impact cratering.
As the shock wave decays, the shocked region decompresses towards more usual pressures and densities. The damage produced by the shock wave raises the temperature of the material. In all but the smallest impacts this increase in temperature is sufficient to melt the impactor, and in larger impacts to vaporize most of it and to melt large volumes of the target. As well as being heated, the target near the impact is accelerated by the shock wave, and it continues moving away from the impact behind the decaying shock wave.

[edit] Excavation

Contact, compression, decompression, and the passage of the shock wave all occur within a few tenths of a second for a large impact. The subsequent excavation of the crater occurs more slowly, and during this stage the flow of material is largely sub-sonic. During excavation, the crater grows as the accelerated target material moves away from the impact point. The target's motion is initially downwards and outwards, but it becomes outwards and upwards. The flow initially produces an approximately hemispherical cavity. The cavity continues to grow, eventually producing a paraboloid (bowl-shaped) crater in which the centre has been pushed down, a significant volume of material has been ejected, and a topographically elevated crater rim has been pushed up. When this cavity has reached its maximum size, it is called the transient cavity.

Herschel Crater on Saturn's moon Mimas

The depth of the transient cavity is typically a quarter to a third of its diameter. Ejecta thrown out of the crater does not include material excavated from the full depth of the transient cavity; typically the depth of maximum excavation is only about a third of the total depth. As a result, about one third of the volume of the transient crater is formed by the ejection of material, and the remaining two thirds is formed by the displacement of material downwards, outwards and upwards, to form the elevated rim. For impacts into highly porous materials, a significant crater volume may also be formed by the permanent compaction of the pore space. Such compaction craters may be important on many asteroids, comets and small moons.
In large impacts, as well as material displaced and ejected to form the crater, significant volumes of target material may be melted and vaporized together with the original impactor. Some of this impact melt rock may be ejected, but most of it remains within the transient crater, initially forming a layer of impact melt coating the interior of the transient cavity. In contrast, the hot dense vaporized material expands rapidly out of the growing cavity, carrying some solid and molten material within it as it does so. As this hot vapor cloud expands, it rises and cools much like the archetypal mushroom cloud generated by large nuclear explosions. In large impacts, the expanding vapor cloud may rise to many times the scale height of the atmosphere, effectively expanding into free space.
Most material ejected from the crater is deposited within a few crater radii, but a small fraction may travel large distances at high velocity, and in large impacts it may exceed escape velocity and leave the impacted planet or moon entirely. The majority of the fastest material is ejected from close to the center of impact, and the slowest material is ejected close to the rim at low velocities to form an overturned coherent flap of ejecta immediately outside the rim. As ejecta escapes from the growing crater, it forms an expanding curtain in the shape of an inverted cone; the trajectory of individual particles within the curtain is thought to be largely ballistic.
Small volumes of un-melted and relatively un-shocked material may be spalled at very high relative velocities from the surface of the target and from the rear of the impactor. Spalling provides a potential mechanism whereby material may be ejected into inter-planetary space largely undamaged, and whereby small volumes of the impactor may be preserved undamaged even in large impacts. Small volumes of high-speed material may also be generated early in the impact by jetting. This occurs when two surfaces converge rapidly and obliquely at a small angle, and high-temperature highly shocked material is expelled from the convergence zone with velocities that may be several times larger than the impact velocity.

[edit] Modification and collapse

Weathering may change the aspect of a crater drastically. This mound on Mars' north pole may be the result of an impact crater that was buried by sediment and subsequently re-exposed by erosion.

In most circumstances, the transient cavity is not stable: it collapses under gravity. In small craters, less than about 4 km diameter on Earth, there is some limited collapse of the crater rim coupled with debris sliding down the crater walls and drainage of impact melts into the deeper cavity. The resultant structure is called a simple crater, and it remains bowl-shaped and superficially similar to the transient crater. In simple craters, the original excavation cavity is overlain by a lens of collapse breccia, ejecta and melt rock, and a portion of the central crater floor may sometimes be flat.

Multi-ringed impact basin Valhalla on Jupiter's moon Callisto

Above a certain threshold size, which varies with planetary gravity, the collapse and modification of the transient cavity is much more extensive, and the resulting structure is called a complex crater. The collapse of the transient cavity is driven by gravity, and involves both the uplift of the central region and the inward collapse of the rim. The central uplift is not the result of elastic rebound which is a process in which a material with elastic strength attempts to return to its original geometry; rather the collapse is a process in which a material with little or no strength attempts to return to a state of gravitational equilibrium.
Complex craters have uplifted centers, and they have typically broad flat shallow crater floors, and terraced walls. At the largest sizes, one or more exterior or interior rings may appear, and the structure may be labeled an impact basin rather than an impact crater. Complex-crater morphology on rocky planets appears to follow a regular sequence with increasing size: small complex craters with a central topographic peak are called central peak craters, for example Tycho; intermediate-sized craters, in which the central peak is replaced by a ring of peaks, are called peak-ring craters, for example Schrödinger; and the largest craters contain multiple concentric topographic rings, and are called multi-ringed basins, for example Orientale. On icy as opposed to rocky bodies, other morphological forms appear which may have central pits rather than central peaks, and at the largest sizes may contain very many concentric rings – Valhalla on Callisto is the type example of the latter.

[edit] Identifying impact craters

Impact crater structure

Shocked polymictic breccia from the Azuara impact structure, Spain.

Some volcanic features can resemble impact craters, and brecciated rocks are associated with other geological formations besides impact craters. Non-explosive volcanic craters can usually be distinguished from impact craters by their irregular shape and the association of volcanic flows and other volcanic materials. An exception is that impact craters on Venus often have associated flows of melted material.
The distinctive mark of an impact crater is the presence of rock that has undergone shock-metamorphic effects, such as shatter cones, melted rocks, and crystal deformations. The problem is that these materials tend to be deeply buried, at least for simple craters. They tend to be revealed in the uplifted center of a complex crater, however.
Impacts produce distinctive shock-metamorphic effects that allow impact sites to be distinctively identified. Such shock-metamorphic effects can include:

Close-up of shatter cones developed in fine grained dolomite from the Wells Creek crater, USA.

• A layer of shattered or "brecciated" rock under the floor of the crater. This layer is called a "breccia lens".
• Shatter cones, which are chevron-shaped impressions in rocks. Such cones are formed most easily in fine-grained rocks.
• High-temperature rock types, including laminated and welded blocks of sand, spherulites and tektites, or glassy spatters of molten rock. The impact origin of tektites has been questioned by some researchers; they have observed some volcanic features in tektites not found in impactites. Tektites are also drier (contain less water) than typical impactites. While rocks melted by the impact resemble volcanic rocks, they incorporate unmelted fragments of bedrock, form unusually large and unbroken fields, and have a much more mixed chemical composition than volcanic materials spewed up from within the Earth. They also may have relatively large amounts of trace elements that are associated with meteorites, such as nickel, platinum, iridium, and cobalt. Note: it is reported in the scientific literature that some "shock" features, such as small shatter cones, which are often reported as being associated only with impact events, have been found in terrestrial volcanic ejecta.
• Microscopic pressure deformations of minerals. These include fracture patterns in crystals of quartz and feldspar, and formation of high-pressure materials such as diamond, derived from graphite and other carbon compounds, or stishovite and coesite, varieties of shocked quartz.

[edit] Lunar crater categorization

In 1978, Chuck Wood and Leif Andersson of the Lunar & Planetary Lab devised a system of categorization of lunar impact craters. They used a sampling of craters that were relatively unmodified by subsequent impacts, then grouped the results into five broad categories. These successfully accounted for about 99% of all lunar impact craters.
The LPC Crater Types were as follows:

• ALC — small, cup-shaped craters with a diameter of about 10 km or less, and no central floor. The archetype for this category is 'Albategnius C'.
• BIO — similar to an ALC, but with small, flat floors. Typical diameter is about 15 km. The lunar crater archetype is Biot.
• SOS — the interior floor is wide and flat, with no central peak. The inner walls are not terraced. The diameter is normally in the range of 15–25 km. The archetype is Sosigenes.
• TRI — these complex craters are large enough so that their inner walls have slumped to the floor. They can range in size from 15–50 km in diameter. The archetype crater is Triesnecker.
• TYC — these are larger than 50 km, with terraced inner walls and relatively flat floors. They frequently have large central peak formations. Tycho is the archetype for this class.

Beyond a couple of hundred kilometers diameter, the central peak of the TYC class disappear and they are classed as basins.

[edit] Lists of craters

List of impact craters on Earth List of craters on Mercury List of craters on the Moon List of craters on Mars List of craters on Venus List of geological features on Phobos List of geological features on Jupiter's smaller moons List of craters on Europa List of craters on Ganymede List of craters on Callisto List of geological features on Saturn's smaller moons List of geological features on Mimas List of geological features on Enceladus

List of geological features on Tethys List of geological features on Dione List of geological features on Rhea List of geological features on Iapetus List of geological features on Puck List of geological features on Miranda List of geological features on Ariel List of craters on Umbriel List of geological features on Titania List of geological features on Oberon List of craters on Triton

[edit] Impact craters on Earth

Main article: List of impact craters on Earth

On Earth, the recognition of impact craters is a branch of geology, as opposed to astronomy on other worlds. Out of many proposed craters, relatively few are confirmed. The following are a sample of articles of confirmed and well-documented impact sites.

Barringer Crater, aka Meteor Crater (Arizona, USA) Chesapeake Bay impact crater (Virginia, USA) Chicxulub, Extinction Event Crater (Mexico) Clearwater Lakes (Quebec, Canada) Gosses Bluff crater (Northern Territory, Australia) Haughton impact crater (Nunavut, Canada) Kaali crater (Estonia) Karakul crater (Tajikistan) Lonar crater (India) Manicouagan crater (Quebec, Canada)

Manson crater (Iowa, USA) Mistastin crater (Labrador, Canada) Nördlinger Ries (Germany) Pingualuit crater (Quebec, Canada) Popigai crater, (Siberia, Russia) Shoemaker crater (Western Australia, Australia) The Siljan Ring (Sweden) Sudbury Basin (Ontario, Canada) Vredefort crater (South Africa) Wolfe Creek Crater (Western Australia, Australia)

See the Earth Impact Database,^[9] a website concerned with over 170 scientifically-confirmed impact craters on Earth.

[edit] Some extraterrestrial craters

• Caloris Basin (Mercury)
• Hellas Basin (Mars)
• Mare Orientale (Moon)
• Petrarch crater (Mercury)
• Skinakas Basin (Mercury)
• South Pole – Aitken basin (Moon)
• Herschel crater (Mimas)

[edit] Largest named craters in the Solar System

1. North Polar Basin/Borealis Basin - Mars - Diameter: 10,600 km
2. South Pole-Aitken basin - Moon - Diameter: 2,500 km
3. Hellas Basin - Mars - Diameter: 2,100 km
4. Caloris Basin - Mercury - Diameter: 1,550 km
5. Mare Imbrium - Moon - Diameter: 1,100 km
6. Isidis Planitia - Mars - Diameter: 1,100 km
7. Mare Tranquilitatis - Moon - Diameter: 870 km
8. Argyre Planitia - Mars - Diameter: 800 km
9. Rembrandt – Mercury – Diameter: 715 km
10. Mare Serenitatis - Moon - Diameter: 700 km
11. Mare Nubium - Moon - Diameter: 700 km
12. Beethoven - Mercury - Diameter: 625 km
13. Valhalla - Callisto - Diameter: 600 km, with rings to 4,000 km diameter
14. Hertzsprung - Moon - Diameter: 590 km
15. Turgis - Iapetus - Diameter: 580 km
16. Apollo - Moon - Diameter: 540 km
17. Huygens - Mars - Diameter: 470 km
18. Schiaparelli - Mars - Diameter: 470 km
19. Menrva - Titan - Diameter: 440 km
20. Korolev - Moon - Diameter: 430 km
21. Dostoevskij - Mercury - Diameter: 400 km
22. Odysseus - Tethys - Diameter: 400 km
23. Tolstoj - Mercury - Diameter: 390 km
24. Goethe - Mercury - Diameter: 380 km
25. Tirawa - Rhea - Diameter: 360 km
26. Mare Orientale - Moon - Diameter: 350 km, with rings to 930 km diameter
27. Epigeus - Ganymede - Diameter: 340 km
28. Gertrude - Titania - Diameter: 320 km
29. Asgard - Callisto - Diameter: 300 km, with rings to 1,400 km diameter
30. Vredefort crater - Earth - Diameter: 300 km
31. Mead - Venus - Diameter: 270 km

There are approximately twelve more impact craters/basins larger than 300 km on the Moon, five on Mercury, and four on Mars.^[10] Large basins, some unnamed but mostly smaller than 300 km, can also be found on Saturn's moons Dione, Rhea and Iapetus.

[edit] See also

• Cretaceous–Tertiary extinction event
• Impact event
• Impact depth
• Nemesis
• Rampart crater
• Ray system
• Peter H. Schultz

[edit] References

1. ^ Basaltic Volcanism Study Project. (1981). Basaltic Volcanism on the Terrestrial Planets; Pergamon Press, Inc: New York, p. 746. http://articles.adsabs.harvard.edu//full/book/bvtp./1981//0000746.000.html.
2. ^ Consolmagno, G.J.; Schaefer, M.W. (1994). Worlds Apart: A Textbook in Planetary Sciences; Prentice Hall: Englewood Cliffs, NJ, p.56.
3. ^ French, B.M. (1998). Traces of Catastrophe: A Handbook of Shock-Metamorphic Effects in Terrestrial Meteorite Impact Structures; Simthsonian Institution: Washington DC, p. 97. http://www.lpi.usra.edu/publications/books/CB-954/CB-954.intro.html.
4. ^ Carr, M.H. (2006) The surface of Mars; Cambridge University Press: Cambridge, UK, p. 23.
5. ^ Grieve R.A.; Shoemaker, E.M. (1994). The Record of Past Impacts on Earth in Hazards due to Comets and Asteroids, T. Gehrels, Ed.; University of Arizona Press, Tucson, AZ, pp. 417-464.
6. ^ Grieve, R.A.F.; Cintala, M.J.; Tagle, R. (2007). Planetary Impacts in Encyclopedia of the Solar System, 2nd ed., L-A. McFadden et al. Eds, p. 826.
7. ^ Shoemaker, E.M.; Shoemaker, C.S. (1999). The Role of Collisions in The New Solar System, 4th ed., J.K. Beatty et al., Eds., p. 73.
8. ^ Grieve, R.A.F. (1990) Impact Cratering on the Earth. Scientific American, April 1990, p. 66.
9. ^ Impact Cratering on Earth
10. ^ USGS Astrogeology: Gazetteer of Planetary Nomenclature

• Charles A. Wood and Leif Andersson, New Morphometric Data for Fresh Lunar Craters, 1978, Proceedings 9th Lunar and Planet. Sci. Conf.
• Bond, J. W., "The development of central peaks in lunar craters", Earth, Moon, and Planets, vol. 25, December 1981.
• Melosh, H.J., 1989, Impact cratering: A geologic process: New York, Oxford University Press, 245 p.
• Baier, J., Die Auswurfprodukte des Ries-Impakts, Deutschland, in Documenta Naturae, Vol. 162, 2007. ISBN 978-3-86544-162-1

Sumber :
http://en.wikipedia.org/wiki/Impact_crater

 

Psikopat

Psychopathy ( /saɪˈkɒpəθi/^[1][2]) was, until 1980, the term used for a personality disorder characterized by an abnormal lack of empathy combined with strongly amoral conduct but masked by an ability to appear outwardly normal. The publication of DSM-III changed the name of this mental disorder to Antisocial Personality Disorder and also broadened the diagnostic criteria considerably by shifting from clinical inferences to behavioral diagnostic criteria.^[3] However, the DSM-V working party is recommending a revision of Antisocial Personality Disorder to "Antisocial/Psychopathic Type", with the diagnostic criteria having a greater emphasis on character than on behavior.^[4] The ICD-10 diagnostic criteria of the World Health Organization also lacks psychopathy as a personality disorder, its 1992 manual including Dissocial (Antisocial) Personality Disorder, which encompasses amoral, antisocial, asocial, psychopathic, and sociopathic personalities.^[5]
Despite being currently unused in diagnostic manuals, psychopathy and related terms such as psychopath are still widely used by mental health professionals and laymen alike. In particular, NATO has funded a series of Advanced Study Institutes on psychopathy both prior to DSM-III and since. Researcher Robert Hare has been a particular champion of the term and his Hare Psychopathy Checklist is the standard tool for differentiating between those with Antisocial Personality Disorder (APD) and the subset who are psychopaths. According to this scale, the prevalence of APD is two to three times that of psychopathy.^[6]
According to Christopher J. Patrick in his 'Handbook of Psychopathy' clinicians generally believe that there is neither a cure nor any effective treatment for psychopathy; there are no medications that can instill empathy, while psychopaths who undergo traditional talk therapy only become more adept at manipulating others.^[7] However, other researchers suggest that psychopaths may benefit as much as others from psychological treatment, at least in terms of effect on behavior.^[8] According to Hare, the consensus among researchers in this area is that psychopathy stems from a specific neurological disorder which is biological in origin and present from birth^[9] although this was not what was reported by a 2008 review which instead indicated multiple causes and variation between individuals.^[10] Hare estimates that about one percent of the population are psychopaths.^[11]

*Classification

Main article: Classification of mental disorder

The classification of mental disorders, also known as psychiatric nosology or taxonomy, is a key aspect of psychiatry and other mental health professions and an important issue for consumers and providers of mental health services. There are currently two widely established systems for classifying mental disorders—Chapter V of the International Classification of Diseases (ICD-10) produced by the World Health Organization (WHO) and the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) produced by the American Psychiatric Association (APA). Both list categories of disorders thought to be distinct types, and have deliberately converged their codes in recent revisions so that the manuals are often broadly comparable, although significant differences remain. Other classification schemes may be in use more locally, for example the Chinese Classification of Mental Disorders. Other manuals have some limited used by those of alternative theoretical persuasions, such as the Psychodynamic Diagnostic Manual.

* Characteristics

The prototypical psychopath has deficits or deviances in several areas: interpersonal relationships, emotion, and self-control. Psychopaths gain satisfaction through antisocial behavior, and do not experience shame, guilt, or remorse for their actions.^[12][13][14] Psychopaths lack a sense of guilt or remorse for any harm they may have caused others, instead rationalizing the behavior, blaming someone else, or denying it outright.^[15] Psychopaths also lack empathy towards others in general, resulting in tactlessness, insensitivity, and contemptuousness. All of this belies their tendency to make a good, likable first impression. Psychopaths have a superficial charm about them, enabled by a willingness to say anything without concern for accuracy or truth. Shallow affect also describes the psychopath's tendency for genuine emotion to be short lived and egocentric with an overall cold demeanor. Their behavior is impulsive and irresponsible, often failing to keep a job or defaulting on debts.^[15] Psychopaths also have a markedly distorted sense of the potential consequences of their actions, not only for others, but also for themselves. They do not deeply recognize the risk of being caught, disbelieved or injured as a result of their behaviour.^[16]
Researcher Robert Hare, whose Hare Psychopathy Checklist is widely used, describes psychopaths as "intraspecies predators".^[17] Also R.I. Simon uses the word predator to describe psychopaths.^[18] Elsewhere Hare and others write that psychopaths "use charisma, manipulation, intimidation, sexual intercourse and violence"^{[19][20][21][verification needed]} to control others and to satisfy their own needs. Hare states that: "Lacking in conscience and empathy, they take what they want and do as they please, violating social norms and expectations without guilt or remorse".^[22] He previously stated that: "What is missing, in other words, are the very qualities that allow a human being to live in social harmony".^[23]
According to Hare, many psychopaths are superficially charming, and can excellently mimic normal human emotion;^[9] some psychopaths can blend in, undetected, in a variety of surroundings, including corporate environments.^[24]

*Perceptual/emotional recognition deficits

Facial affect recognition

In a 2002 study, David Kosson and Yana Suchy, et al. asked psychopathic inmates to name the emotion expressed on each of 30 faces; compared to the control group, psychopaths had a significantly lower rate of accuracy in recognizing disgusted facial affect but a higher rate of accuracy in recognizing anger. Additionally, when "conditions designed to minimize the involvement of left-hemispheric mechanisms" (i.e. sadness) were used, psychopaths had more difficulty accurately identifying emotions. This study did not replicate Blaire, et al. (1997)'s findings that psychopaths are specifically less sensitive to nonverbal cues of fear or distress.^[25]

 Vocal affect recognition

In a 2002 experiment, Blair, Mitchell, et al. used the Vocal Affect Recognition Test to measure psychopaths' recognition of the emotional intonation given to connotatively neutral words. Psychopaths tended to make more recognition errors than controls with a particularly high rate of error for sad and fearful vocal affect.^[26]

Stroop tasks

A 2004 experiment tested the hypothesis of overselective attention in psychopaths using two forms of the Stroop color-word and picture-word tasks: with color/picture and word separated and with color/picture and word together. Psychopaths performed significantly worse than controls in the separated Stroop tasks, but performed as well as the controls on standard Stroop tasks.
When split into low-anxious and high-anxious groups, low-anxious psychopaths and low-anxious controls showed less interference on the separated Stroop tasks than their high-anxious counterparts; for low-anxious psychopaths, interference was very nearly zero. Researchers concluded the inability to integrate contextual cues depends on the cues' relationship to "the deliberately attended, goal-relevant information."^[27]

* Causes

One twin study suggests that psychopathy has a strong genetic component. The study demonstrates that children with anti-social behavior can be classified into two groups: those who were also callous acquired their behavior by genetic influences, and those who were not callous acquired it from their environment.^[28] "The amygdala is crucial for stimulus-reinforcement learning and responding to emotional expressions, particularly fearful expressions that, as reinforcers, are important initiators of stimulus-reinforcement learning. Moreover, the amygdala is involved in the formation of both stimulus-punishment and stimulus-reward associations. Individuals with psychopathy show impairment in stimulus-reinforcement learning (whether punishment or reward based) and responding to fearful and sad expressions. It is argued that this impairment drives much of the syndrome of psychopathy"(Blair, 2008).^[29]
People scoring ≥25 in the Psychopathy Checklist Revised, with an associated history of violent behavior, appear to have significantly reduced microstructural integrity in their uncinate fasciculus - white matter connecting the amygdala and orbitofrontal cortex. The more extreme the psychopathy, the greater the abnormality.^[30]

*Pathophysiology

Recent studies have triggered theories on determining whether there is a biological relationship between the brain and psychopathy. One theory suggests that psychopathy is associated with both the amygdala, which is associated with emotional reactions and emotion learning, and the prefrontal cortex, associated with impulse control, decision-making, emotional learning and behavioral adaptation.^[31] Some studies have shown there is less "gray matter" in these areas in psychopaths than in non-psychopaths.
There is DT-MRI evidence of breakdowns in the white matter connections between these two important areas in a small British study of 9 criminal psychopaths. This evidence suggests that the degree of abnormality was significantly related to the degree of psychopathy and may explain the offending behaviors.^[32][33]
A 2008 review found various abnormalities (based on group differences from average) reported in the literature, centred on a prefrontal-temporo-limbic circuit — regions that are involved in emotional and learning processes, as well as many other processes. However, the authors report that the people classed as "psychopathic" cannot in fact be seen as a homogeneous group (i.e. as all having the same characteristics), and that the associations between structural changes and psychopathic characteristics do not enable causal conclusions to be drawn. They conclude that psychopathic characteristics involve multifactorial processes including neurobiological, genetic, epidemiological, and sociobiographical (the person's life in society) factors.^[10]

*Diagnosis

Currently, there are no diagnostic criteria in the Diagnostic and Statistical Manual of Mental Disorders for psychopathy. Labeling a person as a psychopath involves forensic measurement, using a diagnostic tool such as the Hare Psychopathy Checklist (PCL-R). The PCL-R is widely considered the "gold standard" for assessing psychopathy. Psychopathy is most strongly correlated with DSM-IV antisocial personality disorder (ASPD), and the ICD-10 antisocial personality disorder and dissocial personality disorder (DPD). However, the PCL-R criteria for identifying a psychopath are stricter than the diagnostic criteria for ASPD or DPD; psychopaths represent a subset of those with ASPD, and psychopaths' traits are more severe.^[34]
One issue related to the assessment of individuals who may exhibit affective, interpersonal, and behavioral features associated with psychopathy is the ability to overcome gender myths when the psychopathy features are present in females.^[35] The Hare Psychopathy Checklist-Revised has both percentiles and T-score tables for male and female offenders.

Hare Psychopathy Checklist

Main article: Hare Psychopathy Checklist

Psychopathy is most commonly assessed with the PCL-R,^[36] which is a clinical rating scale with 20 items. Each of the items in the PCL-R is scored on a three-point (0, 1, 2) scale according to two factors. PCL-R Factor 2 is associated with reactive anger, anxiety, increased risk of suicide, criminality, and impulsive violence.
PCL-R Factor 1, in contrast, is associated with extraversion and positive affect. Factor 1, the so-called core personality traits of psychopathy, may even be beneficial for the psychopath (in terms of non‑deviant social functioning). A psychopath will score high on both factors, whereas someone with ASPD will score high only on Factor 2.^[37] Both case history and a semi-structured interview are used in the analysis.
Because an individual's scores may have important consequences for his or her future, the potential for harm if the test is used or administered incorrectly is considerable. The test can only be considered valid if administered by a suitably qualified and experienced clinician under controlled conditions.^[22][38]

PCL-R items

The following findings are for research purposes only, and are not used in clinical diagnosis. These items cover the affective, interpersonal, and behavioral features. Each item is rated on a score from zero to two. The sum total determines the extent of a person's psychopathy.^[34]

Factor 1

Aggressive narcissism

1. Glibness/superficial charm
2. Grandiose sense of self-worth
3. Pathological lying
4. Cunning/manipulative
5. Lack of remorse or guilt
6. Emotionally shallow
7. Callous/lack of empathy
8. Failure to accept responsibility for own actions

Factor 2

Socially deviant lifestyle

1. Need for stimulation/proneness to boredom
2. Parasitic lifestyle
3. Poor behavioral control
4. Promiscuous sexual behavior
5. Lack of realistic, long-term goals
6. Impulsiveness
7. Irresponsibility
8. Juvenile delinquency
9. Early behavioral problems
10. Revocation of conditional release

Traits not correlated with either factor

1. Many short-term marital relationships
2. Criminal versatility

Comorbidity

Psychopaths may have various mental conditions,^[39] although, in contrast to people with antisocial personality disorder, comorbidity among psychopaths is generally found to be low.^[40][41]
Substance abuse has been associated with psychopathy,^[42] particularly Factor 2 (anti-social behaviour), but not Factor 1 (emotional) scores of the PCL-R.^[39][40] Conduct disorder and ADHD have both been associated with psychopathy; which may be explained by disruption to dorsolateral prefrontal cortex. This area is associated with executive function, which is affected in all three disorders.^[39]
There is some evidence of an association between ASPD and other personality disorders (i.e. histrionic, narcissistic and borderline personality disorders),^[40] however, evidence for a link with psychopathy is more tentative.^[41]
Anxiety may be associated positively with antisocial behaviour, but it is inversely associated with Factor I (emotional) scores on the PCL-R.^[39] Depression is inversely associated with psychopathy.^[39] Although violence may be associated with schizophrenia, there is no conclusive evidence for a link between psychopathy and schizophrenia.^[39][41]
It has been suggested that psychopathy may be comorbid with several other diagnoses than these,^[42] however limited work on comorbidity has been carried out. This may be because of difficulties in using inpatient groups from certain institutions to assess comorbidity, owing to the likelihood of some bias in sample selection.^[39] Furthermore, comorbidity may be more reflective of poor discriminant validity of categories in the DSM-IV than reflective of underlying aetiologically separate conditions.^[40]

No evidence for propensity to sexually-oriented murder

No clinical definition of psychopathy indicates that psychopaths are especially prone to commit sexually-oriented murders, and scientific studies do not suggest that a large proportion of psychopaths have committed these crimes.^{[citation needed]} Although some claim a large proportion of such offenders have been classified as psychopathic, this evidence comes from a single, unrepeated research study using the Rorschach Inkblot Test, an invalid test for psychopathy and for sex offenders,^[43] references not considering psychopathy,^[44] and studies concerning sexual homicide, a somewhat different population than the general class of sex offenders and not from meta-studies combining repeatable results.

* Conceptual models

As a discrete disorder

Hare believes that the Diagnostic and Statistical Manual of Mental Disorders should list psychopathy as a unique disorder, given that psychopathy has no precise equivalent^[38] in either the DSM-IV-TR, where it is most strongly correlated with the diagnosis of antisocial personality disorder, or the ICD-10, which has a partly similar condition called dissocial personality disorder.

Primary-secondary distinction

Primary psychopathy was defined by those following this theory as the root disorder in patients diagnosed with it, whereas secondary psychopathy was defined as an aspect of another psychiatric disorder or social circumstances.^[45] Today, primary psychopaths are considered to have mostly Factor 1 traits from the PCL-R (arrogance, callousness, manipulativeness, lying) whereas secondary psychopaths have a majority of Factor 2 traits (impulsivity, boredom proneness, irresponsibility, lack of long-term goals).^[46]
Secondary psychopaths show normal to above-normal physiological responses to (perceived) potential threats; their crimes tend to be unplanned and impulsive with little thought of the consequences.^[47] According to those using this theory, this type have hot tempers and are prone to reactive aggression. They experience normal to above-normal levels of anxiety but are nevertheless highly stimulus-seeking and have trouble tolerating boredom. Their lifestyle may lead to depression and even suicide.
Mealey uses the term "primary psychopathy" to differentiate between psychopathy that is biological in origin and "secondary psychopathy" that results from a combination of genetic and environmental influences.^[48] Lykken prefers sociopathy to describe the latter.
Sellbom and Ben-Porath (2005) describe the distinction:

Some people who engage in violent behavior possess psychopathic personality traits, such as callousness, grandiosity, and fearlessness, and presumably engage in such conduct because they care little about others. Others are impulsive and experience considerable anger, anxiety, and distress and may commit violent acts as a reaction to negative emotions, which are sometimes referred to as "crimes of passion." Indeed, the distinction between primary and secondary psychopathy (including so-called neurotic psychopathy) has long been noted in the psychopathy literature (Karpman, 1947; Lykken, 1995).^[49]

This distinction closely resembles the distinction between instrumental and impulsive/reactive crime/violence in the field of criminology.^{[citation needed]}
Joseph P. Newman et al., who use this concept of psychopathy, have validated David T. Lykken's conceptualization of psychopathy subtypes in relation to Gray's behavioral activation system and behavioral inhibition system.^[50] Newman et al. found measures of primary psychopathy to be negatively correlated with Gray's behavioral inhibition system, a construct intended to measure behavioral inhibition from cues of punishment or nonreward.^[50] In contrast, measures of secondary psychopathy to be positively correlated with Gray's behavioral activation system, a construct intended to measure sensitivity to cues of behavioral approach.^[50]

Psychopathy vs. sociopathy

Hare writes that the difference between sociopathy and psychopathy may "reflect the user's views on the origins and determinates of the disorder."^[51]
In the preface to the fifth edition of The Mask of Sanity, Cleckly stated, "... revisions of the nomenclature have been made by the American Psychiatric Association. The classification of psychopathic personality was changed to that of sociopathic personality in 1958", suggesting that he did not recognise any difference between the conditions.
David T. Lykken proposes psychopathy and sociopathy are two distinct kinds of antisocial personality disorder. He believes psychopaths are born with temperamental differences such as impulsivity, cortical underarousal, and fearlessness that lead them to risk-seeking behavior and an inability to internalize social norms. On the other hand, he claims sociopaths have relatively normal temperaments; their personality disorder being more an effect of negative sociological factors like parental neglect, delinquent peers, poverty, and extremely low or extremely high intelligence. Both personality disorders are the result of an interaction between genetic predispositions and environmental factors, but psychopathy leans towards the hereditary whereas sociopathy tends towards the environmental.^[46]

Three-factor model

Recent statistical analysis using confirmatory factor analysis by Cooke and Michie^[52] indicated a three-factor structure, with those items from factor 2 strictly relating to antisocial behaviour (criminal versatility, juvenile delinquency, revocation of conditional release, early behavioural problems, and poor behavioural controls) removed from the final model. The remaining items are divided into three factors: Arrogant and Deceitful Interpersonal Style, Deficient Affective Experience, and Impulsive and Irresponsible Behavioural Style.^[52]
Hare and colleagues have published detailed critiques of the Cooke & Michie hierarchical ‘three’-factor model, citing severe statistical problems. Hare and colleagues note that the Cooke & Michie model actually contains ten factors, and results in impossible parameters (negative variances). Hare and colleagues also note conceptual problems with this model.^[53]

Discrete vs. continuous

As part of the larger debate on whether personality disorders are distinct from normal personality, or if they are extremes on various dimensions of normal personality, is the debate on whether psychopathy represents something "qualitatively different" from normal personality, or a "continuous dimension" shading from normality into severely psychopathic. Otto Kernberg believed psychopathy should fall under a spectrum of pathological narcissism, that ranged from narcissistic personality on the low end, malignant narcissism in the middle, and psychopathy at the high end.^[54]
Early taxonometric analysis from Harris and colleagues^[55] indicated a discrete category may underlie psychopathy, however this was only found for the behavioural Factor 2 items, indicating this analysis may be related to Anti-social Personality Disorder rather than psychopathy per se. Marcus, John, and Edens more recently performed a series of statistical analysis on previously attained PCL–R and PPI scores and concluded psychopathy may best be conceptualized as having a "dimensional latent structure" like depression.^[56]

* Screening

Childhood precursors

Psychopathic tendencies can sometimes be recognized in childhood or early adolescence. If recognized, a diagnosis of Conduct Disorder, or possibly the related Oppositional Defiant Disorder, may be given. However, while these childhood signs have been found in a significantly higher proportion of psychopaths than in the general population, it must be stressed that not all such childhood diagnoses turn out to be psychopaths as adults, or even disordered at all. Therefore, psychopathy is not normally diagnosed in children or adolescents, and some jurisdictions explicitly forbid diagnosing minors with psychopathy and similar personality disorders. This is because such a diagnosis "fails to capture the emotional, cognitive, and interpersonality traits — egocentricity and lack of remorse, empathy, or guilt - that are so important in the diagnosis of psychopathy."^[57]
Children showing strong psychopathic precursors often appear immune to punishment; nothing seems to modify their undesirable behavior. Consequently parents usually give up, and the behavior worsens.^[58]
The following childhood indicators are to be seen not as to the type of behavior, but as to its relentless and unvarying occurrence. Not all must be present concurrently, but at least a number of them need to be present over a period of years.^[59] These indicators are sufficient - but not necessary - indicators of possible psychopathy.^{[citation needed]}

• An extended period of bedwetting past the preschool years not due to any medical problem.
• Precocious sadism, often expressed as profound animal abuse.
• Pathological firesetting lacking in obvious homicidal intent. Not to be confused with playing with matches, which is not uncommon for preschoolers. This is the deliberate setting of destructive fires with utter disregard for the property and lives of others.
• Lying, often without discernible objectives, extending beyond a child's normal impulse not to be punished. These lies are so extensive it is often impossible to know lies from truth.
• Theft and truancy.
• Aggression to peers and relatives, which can include physical and verbal abuse, getting others into trouble, or a campaign of psychological torment.

The three indicators—bedwetting, cruelty to animals and firestarting, known as the Macdonald triad—were first described by J.M. MacDonald as "red flag" indicators of psychopathy and future episodic aggressive behavior.^[60] However, subsequent research has found that bedwetting is not a significant factor.^[61] Moreover, as mentioned previously, these indicators are sufficient - but not necessary - indicators of possible psychopathy.^{[citation needed]}
The question of whether young children with early indicators of psychopathy respond poorly to intervention compared to conduct disordered children without these traits have only recently been examined in controlled clinical research. The empirical findings from this research have been consistent with broader anecdotal evidence, pointing to poor treatment outcomes.^[62]

*Management

Clinical management

In practice, mental health professionals rarely treat psychopathic personality disorders as they are often considered untreatable and no interventions have proved to be effective. However, some of the difficulty has been attributed to the lack of clarity around the concept and diagnosis of psychopathy; the threat of danger to staff, or deceit or poor motivation from patients; and a lack of follow-up to test effectiveness. Despite pessimism, as of 1999, treatment of patients still takes place in a variety of psychiatric hospitals and secure units, and the research has indicated that some individuals do show some improvements when the right treatment is identified, and that longer periods of therapy often produce better results.^[63]
It has been shown that punishment and behavior modification techniques do not improve the behavior of psychopaths. Psychopathic individuals have been regularly observed to become more cunning and better able to hide their behaviour. It has been suggested that traditional therapeutic approaches actually make psychopaths more adept at manipulating others and concealing their behavior. They are generally considered to be not only incurable but also untreatable.^[7]
However, some researchers suggest that psychopaths can benefit as much as others from psychological treatment, at least in terms of criminal behaviors.^[8] For example, one therapeutic approach to juveniles reports reduced re-offending over a two year period compared to usual care.^[64]

*Legal response

United Kingdom

In the United Kingdom, "Psychopathic Disorder" was legally defined in the Mental Health Act (UK)^[65] as, "a persistent disorder or disability of mind (whether or not including significant impairment of intelligence) which results in abnormally aggressive or seriously irresponsible conduct on the part of the person concerned." This term, which did not equate to psychopathy, was intended to reflect the presence of a personality disorder, in terms of conditions for detention under the Mental Health Act 1983. With the subsequent amendments to the Mental Health Act 1983 within the Mental Health Act 2007, the term 'psychopathic disorder' has been abolished, with all conditions for detention (e.g. mental illness, personality disorder, etc.) now being contained within the generic term of 'mental disorder'.
In England and Wales the diagnosis of dissocial personality disorder is grounds for detention in secure psychiatric hospitals under the Mental Health Act if they have committed serious crimes, but since such individuals are disruptive for other patients and not responsive to treatment this alternative to prison is not often used.^[66]

United States

Psychopathy has quite separate legal and judicial definitions that should not be confused with the medical definition. The American Psychiatric Association is vigorously opposing any non-medical or legal definition of what purports to be a medical condition "without regard for scientific and clinical knowledge." ^[67] Various states and nations have at various times enacted laws specific to dealing with psychopaths.
In the United States approximately twenty states currently have provisions for the involuntary civil commitment for sex offenders or sexual predators, under Sexually violent predator acts, avoiding the use of the term "psychopath." These statutes and provisions are controversial and are being reviewed by the U.S. Supreme Court as a violation of a person's Fourteenth Amendment rights.^[68] (See Foucha v. Louisiana for an example.^[69])

Washington

Washington State Legislature ^[70] defines a "Psychopathic personality" to mean "the existence in any person of such hereditary, congenital or acquired condition affecting the emotional or volitional rather than the intellectual field and manifested by anomalies of such character as to render satisfactory social adjustment of such person difficult or impossible."^[68] The same statute defines the "sexual psychopath" as "any person who is affected in a form of psychoneurosis or in a form of psychopathic personality, which form predisposes such person to the commission of sexual offenses in a degree constituting him a menace to the health or safety of others" for prison sentencing purposes in the Sentencing Reform Act of 1981.^[70]

California

California enacted a psychopathic offender law in 1939, since greatly outmoded and revised,^[71] that defined a psychopath solely in terms of offenders with a predisposition "to the commission of sexual offenses against children." A 1941 law^[72] attempted to further clarify this to the point where anyone examined and found to be psychopathic was to be committed to a state hospital and anyone else was to be sentenced by the courts. However, these laws were enacted years before the American Psychiatric Association began publishing the Diagnostic and Statistical Manual of Mental Disorders which is used today for diagnosis and does not include "psychopathic offender". Hence, these laws are of historical interest only.

*Prognosis

Release rate among convicted criminals

Findings indicate psychopathic convicts have a 2.5 time higher probability of being released from jail than undiagnosed convicts, even though they are more likely to recidivate.^[73]

*Epidemiology

It is estimated that approximately one percent of the general population are psychopaths.^[11] According to an unsourced article in popular science magazine Scientific American, studies indicate that about 25% of prison inmates meet diagnostic criteria for psychopathy.^[8] However, recent British studies have reported a community prevalence of 0.6%, consistent with the estimate given by the screening version of the psychopathy checklist^[74] and a prisoner prevalence of 7.7% in men and 1.9% in women.^[75]

*History

The current concept of psychopathy has been thematically linked to writings by Theophrastus, a student of Aristotle in Ancient Greece, whose description of The Unscrupulous Man is said to embody the characteristics of psychopathy:^[76]

"The Unscrupulous Man will go and borrow more money from a creditor he has never paid ... When marketing he reminds the butcher of some service he has rendered him and, standing near the scales, throws in some meat, if he can, and a soup-bone. If he succeeds, so much the better; if not, he will snatch a piece of tripe and go off laughing."

In 1801, Philippe Pinel described patients who were mentally unimpaired but nonetheless engaged in impulsive and self-defeating acts. He saw them as la folie raisonnante ("insane without delirium") meaning they fully understood the irrationality of their behavior but continued with it anyway.
The scientific study of individuals thought to lack a conscience flourished in the latter half of the 19th century. Notably, Cesare Lombroso rejected the view that criminality could occur in anyone and instead sought to identify particular "born criminals" whom he thought showed certain physical defects.^[77]
By the turn of the 20th century, Henry Maudsley had begun writing about the "moral imbecile", and was arguing such individuals could not be rehabilitated by the correctional system.^[78] Maudsley included the psychopath's immunity to the reformational effects of punishment, owing to their refusal to anticipate further failure, and punishment.^{[citation needed]} In 1904, Emil Kraepelin described four types of personalities similar to antisocial personality disorder. By 1915 he had identified them as defective in either affect or volition, dividing the types further into different categories, only some of which correspond to the current descriptions of antisocial personality disorder.^[79]
In 1909, Birnbaum introduced the term "sociopathic", intended to emphasize the social causes of antisocial behavior.
The Mask of Sanity by Hervey M. Cleckley, M.D., first published in 1941,^[47] is considered a seminal work which provided a vivid series of case studies of individuals (mostly prisoners) described by Cleckley as psychopathic. Cleckley proposed 16 characteristics of psychopathy. The title refers to the "mask" of normality that Cleckley thought concealed the disorganization or mental disorder of what he saw as the psychopathic person.^[80]
A 1977 study, however, found little relationship with the characteristics commonly attributed to psychopaths and concluded that the concept was being used too widely and loosely.^[81]
The American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders incorporated various concepts of psychopathy/sociopathy/antisocial personality in early versions but, starting with the DSM-III in 1980, used instead a diagnosis of antisocial personality disorder. This was based on some of the criteria put forward by Cleckley but operationalized in behavioral terms and more specifically related to conduct and criminality. The World Health Organization's ICD incorporates a similar diagnosis of Dissocial Personality Disorder. Both the DSM and the ICD state that psychopathy (or sociopathy) are synonyms of their diagnosis.
However, there remained no international agreement on the diagnosis of psychopathy. One author referred to it in 1987 as an "infinitely elastic, catch-all category".^[82] In 1988, Blackburn wrote in the British Journal of Psychiatry that the concept as commonly used in psychiatry is little more than a moral judgement masquerading as a clinical diagnosis, and argued that it should be scrapped.
Robert Hare developed a Psychopathy Checklist in 1980 based on the psychopath construct advanced by Cleckley, and later revised it in the 1990s (including the removal of two items).^[76] While the official diagnostic manuals had moved away from the concept as being too vague and difficult to reliably assess, Hare's questionnaire would be increasingly used in research studies on psychopathy mainly in forensic (criminal) settings.

^{Sumber :
http://en.wikipedia.org/wiki/Psychopathy}