Brain Fiction: Self-Deception and the Riddle of
Confabulation. William Hirstein. xii + 289 pp. MIT Press, 2005. $35.
"Know thyself," urged the inscription over the entrance to
the temple of Apollo at Delphi, setting a goal for Western
philosophy and many of the sciences it would ultimately spawn.
Although nobody claims that self-knowledge is easy, certain basic
facts about oneself seem direct and immediate: For example, I know
whether I am now seeing properly, whether I am moving my arm, which
of my thoughts are memories and which fantasies, and whether I am
recognizing a familiar face. We are so intimate with these basic
perceptual and cognitive capacities that it is difficult to imagine
being wrong about such matters. Nonetheless, following brain injury
even these simple insights can miscarry.
A patient with Korsakoff's syndrome, for example, reports that he
spent the weekend at the beach, when in fact he was in the hospital.
His memory is impaired, but he has replaced his lost history with a
confabulation. However, he neither notices his amnesia nor questions
his own story; concerning his own past, he doesn't know that he
doesn't know. For another example, take the stroke patient who is
paralyzed on her left side yet claims that she is not impaired,
asserting that she is moving her immobile arm despite obvious
evidence to the contrary. Even stranger, a patient with Anton's
syndrome denies his own blindness, attributing his complete visual
disability to "dim lighting" or poor glasses. A sufferer
from Capgras's syndrome claims that her immediate family members
have been replaced by impostors. And someone with Cotard's syndrome
reports that he is dead and that everyone around him is dead too.
These sincere claims are almost impervious to correction, even when
the people making them are baldly confronted with the facts. Having
someone point out the contradictions just generates more
confabulations or, at best, temporary concessions.
Individually, paradoxical syndromes like these provoke case studies:
The Man Who Mistook His Wife for a Hat and its
successors popularized a venerable neurological tradition of rich
description of particular individuals. A more difficult exercise is
to seek commonalities among these bizarre syndromes and from there
attempt to discern the underlying explanations in terms of brain
function. In Brain Fiction, neurophilosopher William
Hirstein has made this attempt.
Confabulation is a common expression of a variety of brain injuries,
but of course not all lead to this symptom. Providing a general
analysis of what confabulation is—its definition—is a
fit task for a philosopher. Sorting through a huge literature on the
causes of the confabulation syndromes, none of them simple, requires
neurological experience and great effort, which Hirstein also brings
to the task.
The confabulation syndromes, Hirstein suggests, reflect
"knowledge deficits." Confabulators suffer from a
derailment of processes by which we ascertain our beliefs about the
world. Their brains produce fast and loose hypotheses but,
crucially, fail to check them for accuracy. Instead, confabulators
experience a "pathological certainty" that whatever
springs to mind is simply true, despite overwhelming evidence to the
contrary. Their inability to cross-check their beliefs blocks them
from acknowledging how deeply flawed their claims are; accordingly,
they can't perceive or even conceive their own deficits.
This plausible characterization of confabulation frames Hirstein's
thorough review of the functional neuroanatomy of the syndromes.
This is the real riddle, and generations of study by neuroscientists
have produced a bewildering array of clues and suggestions, which
Hirstein bravely reviews. A prime suspect is the orbitofrontal
cortex, just over our eyes, which is impaired in Korsakoff's
syndrome and by aneurysms of the anterior communicating artery, two
routes to confabulation. Perhaps this is where the cerebral
cross-check normally occurs?
There are two immediate problems with locating this basic epistemic
function just here, behind the forehead. First, like every other
area of the brain, the orbitofrontal region is mutually innervated
by many other parts of the brain, so its disruption will also
interfere with a number of circuits and perhaps compromise the
normal function of several brain areas. Second, what is this
operation of "checking"? Hirstein vaguely characterizes
checking at different points in the book but notes that certain
kinds of representations are often in play: Frequently confabulators
misrepresent the minds of other people. At one extreme, loved ones
are replaced by impostors—that is, perceptual identity is
trumped by a dislocated representation of the mind of the other. Or,
in Cotard's syndrome, the very idea of mind seems blotted
out—oneself and others are "dead," "empty."
Dramatic mental failures of this sort shade into failures of
empathy, a deficit found in many sociopaths, who also show reduced
function of the frontal cortices. They and others with such
neurological damage are socially disinhibited. For Hirstein this
kind of inappropriate behavior is on the same spectrum as the
epistemically inappropriate statements made by Korsakoff's patients.
Finally, at the anticonfabulatory extreme is a mirror syndrome,
obsessive compulsive disorder. If confabulators suffer from
pathological certainty, then OCD patients suffer from pathological
doubt; accordingly, their frontal lobes are abnormally overactive.
As an aside, I might note that "hypofrontality" is also
frequently observed in schizophrenia (although Hirstein does not
develop this connection). Schizophrenic delusions seem more fixed in
content than typical confabulations, which are jury-rigged on the
fly. This difference may point to disruption in ongoing learning
processes in schizophrenia, arising through the abnormal function of
otherwise normal, intact circuits. Perhaps these same circuits are
offline in the confabulation syndromes, and as a result patients
can't really learn or remember their confabulated claims.
Insult to the frontal lobes is not the only cause of confabulation,
and two other conditions stretch the orbitofrontal hypothesis.
Parietal lobe damage, especially to the right side, produces
hemi-neglect, the puzzling disappearance of the left half of the
patient's world. The lost left includes the left side of the body,
which is paralyzed following these lesions. Yet patients often deny
this paralysis and confabulate in response to the request to move
the affected arm. Sometimes they even deny ownership of the arm.
This occurs in spite of an intact frontal lobe, leading Hirstein to
implicate parietal areas in a circuit that includes the frontal
cortex. The parietal insult knocks this network offline, disabling
the frontal fact-checker in exactly the domain of body and spatial
representation that would normally be served by the lost region.
Severing the connections between the hemispheres also occasions
confabulation. In an appropriate experimental context, stimuli can
be channeled just to the isolated right hemisphere, and it can
respond solo (with a movement, rather than words, because this
hemisphere is generally mute). When the split-brain subject is asked
why she did what she did, the talky left hemisphere confabulates a
motive rather than admit ignorance. This observation leads Hirstein
to conjecture that the left orbitofrontal cortex by itself is
insufficient to curtail confabulation. Bilateral function is somehow required.
Although Hirstein strives to account for confabulation with a single
mechanism, the maze of clinical and anatomical data he reviews
strongly suggests that at the neural level there are different
derailments, depending on the type of brain injury. Confabulators,
after all, remain rational in domains outside of the foci of their
various syndromes, in contrast with more global breakdowns found in
schizophrenia or dementia. Thus perceptual cross-checking may be
domain-specific and not localizable in a single region, circuit or
system in the brain, in which case the explanations of confabulation
would vary accordingly.
The book concludes with a chapter on self-deception, which Hirstein
says is analogous to confabulation. In many familiar ways we can
divert our attention from the checks and censors that might
interfere with our most cherished beliefs; in effect we're
interfering with our own frontal functioning. And so we should, he says:
The truth is depressing. We are going to die, most likely
after illness; all our friends will likewise die; we are tiny
insignificant dots on a tiny planet. Perhaps with the advent of
broad intelligence and foresight comes the need for confabulation
and self-deception to keep depression and its consequent lethargy at
bay. There needs to be a basic denial of our finitude and
insignificance in the larger scene. It takes a certain amount of
chutzpah just to get out of bed in the morning.
Like many books, Brain Fiction is ultimately an
illustration of its own thesis. Faced with diverse and inconclusive
evidence, its author makes some optimistic selections and
conjectures. Readers may find their orbitofrontal cortices saying
"Whoa" to some of Hirstein's more general claims. But it
is only when all the confabulation syndromes are scrutinized
together that their tantalizing inconsistencies emerge. Hirstein's
synoptic review gathers many of the clues, making it an excellent
starting point for thinking about the biological mechanisms that
help us make sense of the world. Personally, I welcome an author
ready to go out on some interesting limbs more than one who hugs the
trunk of proof. Or maybe I'm kidding myself.