                              In the
 United States Court of Appeals
                For the Seventh Circuit
                           ____________

No. 05-1507
SANDRA K. SIMS,
                                                  Plaintiff-Appellant,
                                  v.

JO ANNE B. BARNHART,
                                                 Defendant-Appellee.
                           ____________
             Appeal from the United States District Court
      for the Southern District of Indiana, Indianapolis Division.
        No. 1:04-cv-536-LJM—Larry J. McKinney, Chief Judge.
                           ____________
     ARGUED JANUARY 25, 2006—DECIDED MARCH 22, 2006
                           ____________


  Before POSNER, MANION, and WOOD, Circuit Judges.
  POSNER, Circuit Judge. Sandra Sims was turned down by
an administrative law judge for social security disability
benefits sought by her on the ground that she is severely
impaired by somatoform disorder. She appeals from the
district court’s rejection of her challenge to the admin-
istrative law judge’s decision. That decision is exceptionally
thorough and in trying to pick it apart Sims’s lawyer shows
a lack of awareness of the limitations of “substan-
tial evidence” review, especially in a case such as this in
which the claimant alleges a somatoform disorder. We
confine this opinion to the difficult proof issues raised by
2                                                 No. 05-1507

such an allegation, disposing of Sims’s other grounds in an
unpublished order issued today.
  The term “somatoform disorder” refers to what used to be
called “psychosomatic” illness: one has physical symptoms,
but there is no physical cause. This is a well-attested
phenomenon. E.g., White v. Barnhart, 415 F.3d 654, 656 n. 1
(7th Cir. 2005); Carradine v. Barnhart, 360 F.3d 751, 753-54
(7th Cir. 2004); Vaughn v. Nissan Motor Corp. in U.S.A., Inc.,
77 F.3d 736, 737 (4th Cir. 1996). The problem in the disability
context is proof (and it is a problem for the reviewing court
as well as for the administrative law judge), though it is a
problem only when the severity of the symptoms that are
claimed to be disabling is in dispute. If you are disabled,
you are entitled to disability benefits even if no cause for
your disability can be assigned. E.g., Carradine v. Barnhart,
supra, 360 F.3d at 753; Foote v. Chater, 67 F.3d 1553, 1561
(11th Cir. 1995); Easter v. Bowen, 867 F.2d 1128, 1130 (8th Cir.
1989). The problem of proof arises when the symptoms are
reported by the claimant but not verified by medical
experts. The classic example is pain. Its existence cannot be
verified, and since a person can experience intense, dis-
abling pain even though no physical cause can be found,
there is great difficulty in determining whether the person
really is experiencing the pain that he reports. In such a
case, the administrative law judge must of necessity base
decision on the credibility of the claimant’s testimony.
Credibility determinations can rarely be disturbed by a
reviewing court, lacking as it does the opportunity to
observe the claimant testifying. Only if the trier of fact
grounds his credibility finding in an observation or argu-
ment that is unreasonable or unsupported, as in Zurawski v.
Halter, 245 F.3d 881, 887-88 (7th Cir. 2001), can the finding
be reversed. E.g., Pelkey v. Barnhart, 433 F.3d 575, 578 (8th
No. 05-1507                                                   3

Cir. 2006); Thomas v. Barnhart, 278 F.3d 947, 958-59 (9th Cir.
2002).
  Sims’s case depends critically on her contention, for which
specialists have found no organic basis, that she has tunnel
vision. (Her other claimed disabilities have no possible
merit, as explained in our accompanying, unpublished
order.) It is possible to have severe vision problems that
have no organic cause; the medical literature on somatoform
disorder identifies vision problems— including tunnel
vision—as being among the somatoform symptoms. E.g.,
Deborah N. Black et al., “Conversion Hysteria: Lessons from
Functional Imaging,” 16 J. Neuropsychiatry & Clinical
Neurosciences 246 (2004); Hirofumi Ohkubo, “Visual Field in
Hysteria—Reliability of Visual Field by Goldmann
Perimetry,” 71 Documenta Ophthalmologica 61 (1988). And, to
repeat, if a claimant’s symptoms are severe enough to be
disabling, the fact that they have no organic cause is
irrelevant. Sims might have been able to show this. One of
the medical reports states that her field of vision is only 5
degrees. A normal field of vision is 180 to 200 degrees, Jill
Sardegna & T. Otis Paul, Encyclopedia of Blindness and Vision
Impairment 241 (1991); Richard E. Simmons & Donald A.
Keller, One Pair for a Lifetime 18 (1979), and a field of vision
below 10 degrees is disabling per se under the “grid” that
the Social Security Administration uses to streamline
disability determinations. 20 C.F.R. pt. 404, subpt. P, app. 1,
§ 2.03A. But Sims has abandoned that route, and can obtain
benefits only by demonstrating that she indeed has a
disabling somatoform disorder.
  She was given several tests and the results of all of them
(not just the one we mentioned) indicated that she indeed
has tunnel vision. But just as with the test for impaired
peripheral vision that one has to pass to obtain a driver’s
4                                                 No. 05-1507

license, the tests for tunnel vision are valid only if the
patient cooperates. Joseph C. Thompson et al., “Field of
Dreamers and Dreamed-Up Fields: Functional and Fake
Perimetry,” 103 Ophthalmology 117, 123 (1996). So there is
always a risk that the patient is a malingerer. Id.; S.
Beatty, “Psychogenic Medicine: Non-Organic Visual Loss,”
75 Postgrad. Med. J. 201, 204 (1999); Neil R. Miller & James R.
Keane, “Neuro-Ophthalmologic Manifestations of
Nonorganic Disease,” in Walsh and Hoyt’s Clinical Neuro-
Ophthalmology 1765, 1766 (1988); Roger G. Kathol et al.,
“Functional Visual Loss: I. A True Psychiatric Disorder?,” 13
Psychological Med. 307, 309-11 (1983). And therefore
the results of the tests administered to Sims were not
decisive on whether she really has a disabling somato-
form disorder. In such a case, the administrative law judge
is entitled to require additional evidence. Cf. White v.
Barnhart, 415 F.3d 654, 658 (7th Cir. 2005); Sims v. Barnhart,
309 F.3d 424, 431 (7th Cir. 2002).
  Where might such evidence be found? The type of
somatoform disorder that produces symptoms such as
tunnel vision (the type that used to be called “hysteria” and
now is called “conversion disorder,” Black et al., supra;
see also Kathol et al., supra, at 308) need not also produce
symptoms that a psychiatric examination would reveal,
the way suicidal ideation might evidence depression or
agoraphobia anxiety or paranoid delusions schizophrenia.
But the article by Black and his associates indicates that
brain scans may be able to distinguish real from feigned
symptoms of conversion disorder (apparently, organic brain
disease is present in a majority of cases of conver-
sion disorder, Susan Dufel, “Conversion Disorder,” Apr. 15,
2005, http:www.emedicine.com/emerg/topic112.htm.), and
Sims had not had a brain scan. In addition, the symptoms of
conversion disorder are often precipitated by stress, id.;
No. 05-1507                                                  5

American Psychiatric Association, Diagnostic and Statistical
Manual of Mental Disorders, Text Revision (DSM-IV-TR) 498
(4th ed. 2000), and a psychiatric examination might deter-
mine whether the claimant was experiencing or had recently
experienced stress. No such inquiry was conducted either.
As a result of Sims’s failure to produce evidence beyond the
results of the vision tests, the administrative law judge was
entitled to reject her claim to be totally disabled as a conse-
quence of somatoform disorder.
                                                   AFFIRMED.

A true Copy:
        Teste:

                           _____________________________
                            Clerk of the United States Court of
                              Appeals for the Seventh Circuit




                    USCA-02-C-0072—3-22-06
