Kant maintained that ‘freedom of the will’ is one of the metaphysical issues the human intellect is not fit to tackle. I hope at least to add a tiny tile to the complex mosaic of ‘will and actions’, through the perspective of cognitive neuroscience. I will discuss the cases of people whose intentions to act are hindered by actions they perform apparently against their own will. These people behave as they do because of lesions in particular regions of the brain, the frontal lobes.
Kant maintained that ‘freedom of the will’ is one of the
metaphysical issues the human intellect is not fit to tackle. I hope at
least to add a tiny tile to the complex mosaic of ‘will and actions’,
through the perspective of cognitive neuroscience. I will discuss the
cases of people whose intentions to act are hindered by actions they
perform apparently against their own will. These people behave as they
do because of lesions in particular regions of the brain, the frontal
One evening we took our patient, Mrs GP, to dinner with her family. We
were discussing the implication of her medical condition for her and
her relatives, when, out of the blue and much to her dismay, her left
hand took some leftover fish-bones and put them into her mouth (Della
Sala et al., 1994). A little later, while she was begging it not to
embarrass her any more, her mischievous hand grabbed the ice-cream that
her brother was licking. Her right hand immediately intervened to put
things in place and as a result of the fighting the dessert dropped on
the floor. She apologised profusely for this behaviour that she
attributed to her hand’s disobedience. Indeed she claimed that her hand
had a mind of its own and often did whatever ‘pleased it’. This
condition is known as anarchic hand: people experience a conflict
between their declared will and the action of one of their hands. She
is not the only person with this bizarre syndrome. Another such patient
had problems in choosing TV channels, because ‘no sooner had the right
hand selected one station the left hand would press another button’
Anarchic hand is one of the most intriguing phenomena in neurology. The
complex movements of one hand are apparently directed towards a goal
and are smoothly executed, yet are unintended (according to what the
affected people say). The patients are aware of their bizarre and
potentially hazardous behaviour but cannot inhibit it. They often refer
to the feeling that one of their hands behaves as if it has
a will of its own, but never deny that this capricious hand is part of
their own body. The bewilderment comes from the surprising and unwanted
actions, not from a sensation of the hand’s not belonging (Marchetti
& Della Sala, 1998). This condition seems to demonstrate that
self-ownership of actions can be separated from awareness of actions.
The patients affected are aware of the ‘actions’ of their anarchic
hand, which they know to be their hand and not a robotic counterfeit,
yet they disown them.
Anarchic hand is a symptom so grotesque that it verges on the comic.
Another patient of ours, Mrs GC, often complained that her hand did
what it wanted to do, and tried to control its wayward behaviour by
hitting it violently or talking to it in anger and frustration (Della
Sala et al., 1991). Readers may appreciate the similarities with Dr
Strangelove, the irreverent movie that Stanley Kubrick based on the
novel Red Alert by Peter George, in which a mad German-American nuclear
scientist, played by Peter Sellers, constantly had to grab his right
arm to stop it making a Nazi salute. Dr Strangelove syndrome is the
term by which anarchic hand is now known throughout the popular
Some of the literary and movie descriptions of anarchic hand (see box)
neatly overlap with the anarchic patients’ feelings or reports.
However, it was William Boyd, in his short story ‘Bizarre Situations’
in the collection On the Yankee Station, who embraced an anatomical
interpretation of the syndrome. The main character of this novel does
not know whether or not his left hand shot his best friend’s wife dead.
He had undergone an operation known as callosotomy, where surgeons
sever the bundle of white fibres that join the two cerebral
hemispheres. Indeed, in the wake of the discovery of the specialisation
of the left and right hemispheres, for many years a section of the
corpus callosum (either surgically or due to a pathological process)
has been held to be solely responsible for anarchic hand. Feinberg
(1997) maintained that the key to the anarchic hand is the notion that
you can have two consciousnesses in a single individual.
The idea that ‘Man is not truly one, but truly two’ (Stevenson’s Dr
Jekyll and Mr Hyde), perhaps half good and half bad as in Italo
Calvino’s Cloven Viscount, is entwined with the history of humanity,
and certainly is fascinating from the artist’s point of view. However,
scientifically it is rather simplistic, and as an interpretation for
anarchic hand it proved wrong. The callosal hypothesis of anarchic hand
is slippery on more than one ground. Bear with me for a short
Anarchic hand interpreted as a disconnection between the two
hemispheres would result from the separation between the right
hemisphere motor cortex (governing the left hand) and the left
hemisphere areas devoted to planning and the correct execution of
complex motor activities. Therefore the hand showing the anarchic
behaviour must always be the left hand in right-handers. This
assumption has been debunked by the observation of right-handed
patients with a right anarchic hand (see Goldberg, 1985).
So, if anarchic hand is not caused by inter-hemispheric disconnection,
what does cause it? Our patient GC (Della Sala et al., 1991) who had
right-sided anarchic hand, suffered a subarachnoid haemorrhage – the
rupture of an artery within the brain – eight years before she came to
us. Two days after the haemorrhage she was operated upon by a
neurosurgeon who attempted to clip her broken aneurysm. As a result she
had a stroke. She was left with damage in the anterior part of her
brain, encroaching upon the medial area of her left frontal lobe.
We reviewed 39 detailed cases we could glean from the literature (Della
Sala et al., 1994). It appeared that most of the patients showing
anarchic hand had a lesion encroaching upon the medial wall of the
frontal lobe contralateral to the wayward hand. In particular, lesions
seem to be centred on an area known as the supplementary motor area
(SMA). Each SMA lies in the medial surface of one of the frontal lobes
(see Figure 1). It plays a role in the execution of movements. It is
thought to be responsible for converting intention into self-initiated
actions, or to be involved in the selection of what movement to make.
Several studies converge in demonstrating that the part of the SMA
known as the SMA-proper stores and organises motor subroutines related
to internal drives.
Several physiological single-cell experiments point to the distinction
between a lateral and a medial premotor system. The premotor medial
systems centred on the SMAs are connected with a lateral motor system
(centred on a region sometimes referred to as premotor cortex – PMC).
This lateral system is considered to be responsible for the so-called
responsive movements, which are generated in response to external
stimuli. I will summarise for you one experiment I found particularly
Mushiake et al. (1991) trained monkeys to press buttons in a given
sequence. In one condition, the ‘external condition’, lights told the
monkeys which button to press
(it was a visually guided sequence). In the other condition the monkeys
performed the sequence from memory with no external cues, this was the
The movements made by the monkeys were identical. Yet the SMA cells
were more active during the internal condition and the PMC cells were
during the external, visually guided condition.
Neuroimaging studies provide us with further compelling examples. A
series of experiments carried out in London (see Blakemore et al.,
2002) showed that willed actions are associated with a clear activity
in the medial walls of the frontal lobes. These and other similar
experiments indicate that the control of movements may vary as a
function of whether the action is internally or externally guided. The
SMA-proper will dominate when the task is internally guided. In
contrast, the lateral region becomes more relevant when the environment
triggers the task. A neat account of anarchic hand could be given as a
result from the imbalance of this complex mechanism: a lesion of the
SMA leaves the contralateral hand at the mercy of external stimuli that
operate through the PMC, and it therefore behaves anarchically.
The ‘frontal’ account of anarchic hand makes sense if one considers the
basic role of the frontal lobes in the human brain: to allow
interaction with the environment. The development of the prefrontal
cortex in humans is, in evolutionary terms, both recent and striking.
Even in comparison with squirrels and rhesus monkeys, the relative
proportion of the cortex occupied by the prefrontal region in humans
represents an enormous increase. The comparative recency of the
development of the prefrontal cortex is one of several factors that
have led many to regard the region as the seat of what we believe to be
our distinctive qualities of self-awareness. A lesion in the frontal
lobes will produce a change in the character and habitual behaviour of
the person – they will be at the mercy of environmental triggers and
will not be able to inhibit inappropriate behaviour. The person is not
himself anymore. As poignantly described by Ken Kesey in One Flew over
the Cuckoo’s Nest. When McMurphy returned from having surgery to his
frontal lobes, his mate bellowed: ‘Nothing like him.’
What a person does is not what they would have done before the lesion
to their brain – they should not be held responsible for their actions,
yet they are perfectly aware of what they are doing. The problem is so
acute that Pope Pius XII declared against the practice of lobotomy to
treat (change) socially unbecoming behaviour, maintaining that a lesion
to the frontal lobes would strip a person of free will. This thorny
issue was debated at some length by an ad hoc committee of
ecclesiastics and scientists. They came to the conclusion that the
freedom of will of people affected by such a lesion would be degraded,
and advised against their becoming priests or receiving Holy Communion.
Even more bizarre?
What would happen if, rather than a unilateral lesion giving rise to
contralateral anarchic hand, a person had a bilateral lesion damaging
both the SMAs? The outcome would be another sign of frontal
disinhibition known as ‘utilisation behaviour’, whereby patients show a
compulsive urge to use objects at sight.
Lhermitte (1983), a French colleague, revamped this symptom. Among the
examples he reported, my favourite is that of a 52-year-old lady who
was sitting in the doctor’s surgery, when she spotted some medical
instruments. She immediately picked up the syringe, Lhermitte was fast
enough to take off his jacket and undo his trousers; she bent down to
his buttocks to give the injection.
We have recently assessed a patient, with a bilateral lesion centred on
the SMAs, showing overt episodes of utilisation behaviour (Boccardi et
al., 2002). For instance, while being tested, he spotted an apple and a
knife on a corner of the testing desk. He peeled the apple and ate it.
The examiner asked why he was eating the apple. He replied: ‘Well…it
was there.’ ‘Are you hungry?’ ‘No. Well, a bit.’ ‘Have you not just
finished eating?’ ‘Yes.’ ‘Is this apple yours?’ ‘No.’ ‘And whose apple
is it?’ ‘Yours, I think.’ ‘So why are you eating it?’ ‘Because it is
here.’ On another occasion the experimenter, while adjusting the
video-camera, put his wallet on the table. The patient spotted the
wallet, started to take out all the credit cards and other things, such
as the national insurance number, reading it aloud. The experimenter
asked: ‘Whose wallet is it?’ ‘Yours.’ replied the patient, a bit
baffled by the question, but carrying on ransacking it. Indeed, his
utilisation behaviour was so overt as to become a cause of
embarrassment to his wife, and was her major complaint.
It looks as if by damaging one SMA a person ends up with anarchic hand;
damage to both will elicit utilisation behaviour. In both cases the
affected patients will perform inappropriate actions. The environment
triggers the actions performed by patients showing utilisation
behaviour exactly as it does those of people with anarchic hand.
However, those with utilisation behaviour are not aware that their
behaviour is inappropriate, and they don’t show any conflict between
wanted and unwanted actions. It may well be that the lack of awareness
observed in patients with utilisation behaviour comes from the complete
impairment of the medial system, while patients with anarchic hand
still have some access to their inner ‘Fat Controller’ through the
spared half of the system.
Think about a possible scenario that may apply to us all. One Saturday
morning while driving towards a holiday site to spend your weekend you
cross the usual road to your office. Absentmindedly you may turn and
find yourself driving to the office for a while before recognising your
error. The environment provided a trigger strong enough for you to
initiate an automatic behaviour, which you had to inhibit to go back to
your intended plan. This is what often happens to people affected by
utilisation behaviour who lack the capacity to inhibit behaviour
triggered by the environment. When the actions performed go beyond the
simple toying, manipulation and utilisation of an object, they are
often referred to as ‘environmental dependency syndrome’ (Lhermitte,
Controlling the anarchist inside
Severe forms of environmental dependency syndrome are observed in
patients with large lesions in their frontal lobes (Lhermitte et al.,
1986). Yet, nobody is really immune. Jonathan Miller, the British
physician turned opera director, revealed a very pertinent
autobiographical episode. He was standing by a road waiting for Queen
Elizabeth to pass by, and he was scoffing at all those poor souls
hopping about and waving their hands frantically at the triumphal black
stretch-limousine. Yet, as soon as the mighty car approached his
position he could not refrain from hailing the queenmobile. Disgorging
nationalistic pride? More probably an automatic performance triggered
by the environment that he failed to consciously inhibit. Indeed,
according to a recent neat model of the motor control system (Blakemore
et al., 2002) the deficit responsible for anarchic hand and utilisation
behaviour would reside in the lack of inhibition of these environmental
cues which will generate unwanted actions.
From all that we have
discussed so far, it appears that neuroscience provides us with
examples of inability to inhibit actions triggered by the environment.
So can conscious will only veto undesired actions? From this
perspective it looks as if our brain may have a free ‘won’t’ rather
thana free will.
- Sergio Della Sala is Professor of Human Cognitive Neuroscience and
Honorary Consultant in Neurology at the University of Edinburgh.
‘Anarchic hand’ in fiction
The theme of a hand with a will of its own has captured the imagination of several movie-makers and writers.
The 1935 film Mad Love was based on a Maurice Renard novel about a
pianist whose mutilated hands had been surgically replaced with those
of a criminal which then acted on their own will. A pianist’s severed
hands cropped up again in the 1946 film The Beast with Five Fingers,
and portrayals continued through the 1960s (The Nutty Professor, Dr
Strangelove), 1980s (Evil Dead 2) and 1990s (Body Parts, Idle Hands,
and Me, Myself and Irene).
In Hemingway’s The Old Man and the Sea, the cramped hand would not
conform to the old man’s fish-catching endeavour even when he gently
entreated it to. Other examples abound. Julio Cortazar, in one of the
short novels of Octaedro, Cuello de Gatito Negro, portrayed a girl
whose hand ‘does not want to listen and sometimes to her consternation
does whatever it likes’. Maurice Sheridan Le Fanu in The House in the
Churchyard, presented a disembodied hand trying to choke the hapless
person it was persecuting.
Anarchic vs. alien
Anarchic hand is often referred to in the literature as ‘alien hand’.
However, alien hand is a different syndrome altogether. The confusion
arose owing to a mistranslation from the French and dragged on in
subsequent scientific reports (see Marchetti & Della Sala, 1998,
for a full account). The term prevailed, and alien hand began to mean
different things to different authors.
The abuse of the term alien hand is even more evident in the popular
scientific press. For example, in a pamphlet Oliver Sacks calls a
phantom limb ‘alien’ (Sacks, 1995, p.149); and in a TV documentary (The
Mind Traveller, BBC2, 31 October 1996) described as ‘alien hand’ the
typical involuntary movements and tics shown by a patient with a
Discuss and debate
Does anarchic hand contribute to our understanding of consciousness?
Could neuroscience contribute to the discussion on free will?
Does the brain only allow room for a free won’t?
Has neuroscience got much to say to lawyers about personal responsibility?
Have your say on these or other issues this article raises. E-mail
Letters on firstname.lastname@example.org or contribute to our forum via
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