                    United States Court of Appeals
                          FOR THE EIGHTH CIRCUIT
                                   ___________

                                   No. 10-2251
                                   ___________

Thomas N. Pierzchalski,                 *
                                        *
             Appellant,                 *
                                        * Appeal from the United States
      v.                                * District Court for the Western
                                        * District of Arkansas.
Michael J. Astrue, Commissioner         *
of Social Security Administration,      * [UNPUBLISHED]
                                        *
             Appellee.                  *
                                   ___________

                             Submitted: November 3, 2010
                                Filed: November 17, 2010
                                 ___________

Before BYE, BOWMAN, and COLLOTON, Circuit Judges.
                          ___________

PER CURIAM.


      Thomas N. Pierzchalski appeals the district court’s1 order affirming the denial
of supplemental security income and disability insurance benefits. Upon de novo
review of the record, see Davidson v. Astrue, 501 F.3d 987, 989-90 (8th Cir. 2007),
we find that the Commissioner’s decision is supported by substantial evidence on the


      1
      The Honorable James R. Marschewski, United States Magistrate Judge for the
Western District of Arkansas, to whom the case was referred for final disposition by
consent of the parties pursuant to 28 U.S.C. § 636(c).
record as a whole. As to Pierzchalski’s arguments for reversal, we find that the
administrative law judge (ALJ) gave multiple valid reasons for discounting the
opinion of consulting neuropsychologist Vann Smith, including that Dr. Smith saw
Pierzchalski only once, see Charles v. Barnhart, 375 F.3d 777, 783 (8th Cir. 2004);
we find no evidence of bias on the part of the ALJ, see Rollins v. Massanari, 261 F.3d
853, 857-58 (9th Cir. 2001) (quasi-judicial administrative officers such as ALJs are
presumed unbiased, but presumption can be rebutted by showing conflict of interest
or other specific reason for disqualification); and we conclude that the ALJ was not
required to develop the record further based on Dr. Smith’s new post-hearing
diagnosis of cognitive dysfunction, see Gregg v. Barnhart, 354 F.3d 710, 713 (8th Cir.
2003). Accordingly, we affirm.
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