¶1 At his trial for premeditated first degree murder, petitioner Anthony Tyrone Clark sought to introduce expert testimony regarding his intellectual deficits. Clark asserted this testimony would be relevant to contesting the State’s mens rea evidence and to helping the jury understand Clark’s affect while testifying. The trial court excluded Clark’s proffered expert testimony, but it did allow relevant observation testimony about Clark’s education history, Social Security disability benefits, affect, and actions on the day of the murder.
¶2 We hold that the trial court properly exercised its discretion in making its evidentiary rulings. The court did allow relevant observation testimony from lay witnesses to rebut the State’s mens rea evidence, and Clark does not *645challenge the scope of this testimony on review. However, because Clark purposefully did not assert or plead diminished capacity and the proposed expert testimony was not relevant to any other purpose, the expert testimony was properly excluded. Clark also cannot establish ineffective assistance of counsel or cumulative error, so we affirm his convictions.
FACTUAL BACKGROUND
¶3 Clark killed the victim, D.D.,1 with a single gunshot to the back of his head. D.D.’s body was found in a garbage can behind the triplex apartment building where Clark lived. There were no eyewitnesses to the shooting other than Clark himself. Clark testified that D.D. was trying to get Clark’s mother’s necklace from a high shelf in a closet. Before reaching for the necklace, D.D. removed a gun from his coat pocket, removed the “clip” from the gun, and handed the gun to Clark. 13 Verbatim Report of Proceedings (VRP) (Apr. 15, 2013) at 1594. Clark sat on the floor “messing around with the gun,” aimed it “towards the ceiling of the closet,” and shot D.D. Id. at 1595. Several other witnesses testified about Clark’s actions on the day of the shooting, including Clark asking his neighbors to help sell D.D.’s cocaine and get rid of D.D.’s body. The State theorized that Clark killed D.D. with premeditation in order to steal D.D.’s gun and cocaine. Clark contended the shooting was an accident. The primary disputed issue was thus Clark’s level of intent.
PROCEDURAL HISTORY
¶4 By amended information, the State charged Clark with premeditated first degree murder, first degree felony murder, first degree robbery, unlawful possession of a controlled substance with intent to deliver, and second degree *646unlawful possession of a firearm. Clark pleaded not guilty on all counts.
¶5 Before trial, the defense moved to suppress statements Clark made to police after the shooting, contending that he did not validly waive his Miranda2 rights before speaking to police. To support its motion, the defense offered an expert evaluation by Dr. Brent Oneal.3 At the suppression hearing, Dr. Oneal testified that Clark scored in the bottom first to third percentile in standardized intelligence tests. The court found that Dr. Oneal was a credible witness but denied Clark’s motion to suppress.
¶6 The State then moved to exclude testimony about Clark’s “intellectual deficits” for trial purposes. Clerk’s Papers (CP) at 213 (underlining omitted). Clark argued that Dr. Oneal’s testimony was admissible for three purposes: (1) to help the jury understand Clark’s affect during testimony, (2) to explain why Clark does not work, and (3) to contest the State’s mens rea evidence. The court granted the State’s motion in part and excluded Dr. Oneal’s testimony because in light of the fact that Clark specifically disavowed any intention to argue diminished capacity, expert testimony on Clark’s intellectual deficits would be irrelevant and confusing to the jury. It did, however, allow for relevant observation testimony bearing on Clark’s intellectual deficits, including his participation in special education, his receipt of Social Security disability benefits, and “that people [who] knew him considered him slow or tended to discount his testimony.” VBP (Dec. 17, 2012) at 20. The court also left open the possibility for additional evidence regarding Clark’s circumstances and abilities if the State “unfairly sanitized” those facts at trial. VRP (Feb. 15, 2013) at 20.
*647¶7 At the beginning of jury selection, outside the presence of the jury panel, the court noted that some jurors might be confused about whether the death penalty was being sought, given that Clark was charged with murder. The court invited counsel to handle that issue as it felt was appropriate. During individual questioning, the State informed one prospective juror, who was not ultimately seated in this case, that it was not seeking the death penalty. 2 VRP (Mar. 11, 2013) at 120; 5 VRP (Mar. 13, 2013) at 490. It twice repeated that information in front of all the prospective jurors. 5 VRP (Mar. 13, 2013) at 372, 419. The defense did not object at any time.
¶8 The defense renewed its request to admit Dr. Oneal’s testimony several times throughout the course of the trial, arguing that the testimony was necessary to rebut the State’s mens rea evidence and to explain Clark’s affect when he testified. Nevertheless, the defense consistently maintained that it was not asserting diminished capacity. The court adhered to its ruling excluding Dr. Oneal’s testimony and reminded counsel that relevant observation testimony by lay witnesses was admissible.
¶9 The defense elicited testimony that Clark had been in special education, had an individualized education plan, and received Social Security disability benefits.4 It relied on this evidence in its closing argument, emphasizing that Clark was “not your average 20 year old” and arguing that in light of Clark’s actual intellectual abilities, the State had not proved mens rea on the murder change. 15 VRP (Apr. 17, 2013) at 1826.
¶10 The jury was instructed on premeditated first degree murder and the lesser-included offenses of intentional second degree murder, reckless first degree manslaughter, *648and negligent second degree manslaughter. Clark was convicted of premeditated first degree murder as charged, as well as all the other charged counts, so no verdict was returned on the lesser-included offenses.
¶11 The court denied Clark’s request for an exceptional sentence downward and imposed sentences at the bottom of the standard range.5 The Court of Appeals affirmed in all relevant aspects. State v. Clark, No. 45103-4-II (Wash. Ct. App. June 23, 2015) (unpublished), http://www.courts.wa.gov /opinions/.6 We granted Clark’s petition for review. State v. Clark, 184 Wn.2d 1019, 361 P.3d 746 (2015).
ISSUES
¶12 A. Did the trial court properly exclude expert testimony regarding Clark’s intellectual deficits?
¶13 B. Was trial counsel ineffective for failing to object when the State informed prospective jurors that it was not seeking the death penalty?
¶ 14 C. Did cumulative error deprive Clark of his right to a fair trial?
STANDARD OF REVIEW
¶15 We review the trial court’s evidentiary rulings for abuse of discretion and defer to those rulings unless “ ‘no reasonable person would take the view adopted by the trial court.’ ” State v. Atsbeha, 142 Wn.2d 904, 914, 16 P.3d 626 (2001) (internal quotation marks omitted) (quoting State v. Ellis, 136 Wn.2d 498, 504, 963 P.2d 843 (1998)). If the court *649excluded relevant defense evidence, we determine as a matter of law whether the exclusion violated the constitutional right to present a defense. State v. Jones, 168 Wn.2d 713, 719, 230 P.3d 576 (2010).
¶16 To prevail on a claim of ineffective assistance of counsel, a defendant must show that trial counsel’s performance was “deficient,” and that “but for counsel’s deficient performance, there is a ‘reasonable probability’ that the outcome would have been different.” State v. Hicks, 163 Wn.2d 477, 486, 181 P.3d 831 (2008) (quoting State v. Cienfuegos, 144 Wn.2d 222, 227, 25 P.3d 1011 (2001)). For relief based on the cumulative error doctrine, the defendant must show that while multiple trial errors, “standing alone, might not be of sufficient gravity to constitute grounds for a new trial, the combined effect of the accumulation of errors most certainly requires a new trial.” State v. Coe, 101 Wn.2d 772, 789, 684 P.2d 668 (1984). Both ineffective assistance of counsel and cumulative error present constitutional issues, which we review de novo. State v. Samalia, 186 Wn.2d 262, 269, 375 P.3d 1082 (2016).
ANALYSIS
¶17 Clark argues the trial court erred in excluding Dr. Oneal’s expert testimony because it was relevant to his defense, even though he never asserted or pleaded diminished capacity. It is true that observation testimony regarding relevant facts is generally admissible and does not implicate the pleading requirements for diminished capacity, even if offered to rebut the State’s mens rea evidence. However, expert opinion testimony that a defendant has a mental disorder that impaired the defendant’s ability to form the requisite mens rea is relevant only to diminished capacity. Diminished capacity must be affirmatively pleaded before trial, and in this case, Clark specifically disavowed any intent to plead diminished capacity. The court thus properly allowed relevant observation testimony tending to *650rebut the State’s mens rea evidence and properly excluded expert testimony that was not relevant absent a diminished capacity defense. To the extent, if any, that the court unduly restricted the scope of allowable observation testimony by lay witnesses, Clark does not raise that issue on review. He does not otherwise show reversible error, and we therefore affirm.
A. The court properly excluded Dr. Oneal’s testimony
¶18 Expert testimony is admissible “[i]f scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue.” ER 702. The defense contends that Dr. Oneal’s expert testimony would have assisted the jury to determine a fact in issue—Clark’s level of intent—and would also have helped the jury to understand the evidence by explaining Clark’s unusually flat affect while he was testifying. However, because the defense did not plead diminished capacity or show that Dr. Oneal’s testimony was otherwise relevant, his expert testimony was properly excluded.
1. Dr. Oneal’s testimony was not admissible to rebut the State’s mens rea evidence
¶19 Clark argues that Dr. Oneal’s expert testimony should have been admitted for the purpose of rebutting the State’s mens rea evidence even though Clark did not plead diminished capacity because Dr. Oneal’s testimony was not actually diminished capacity evidence. Alternatively, he argues that trial counsel’s failure to assert diminished capacity did not warrant exclusion of Dr. Oneal’s testimony. These arguments are inconsistent with both the record and the law.
¶20 Diminished capacity “allows a defendant to undermine a specific element of the offense, a culpable mental state, by showing that a given mental disorder had a specific effect by which his ability to entertain that mental state was diminished.” State v. Gough, 53 Wn. App. 619, 622, *651768 P.2d 1028 (1989). The intent to assert diminished capacity must “be declared pretrial.” State v. Harris, 122 Wn. App. 498, 506, 94 P.3d 379 (2004) (citing CrR 4.7(b)(1), (2)(xiv)). Pretrial disclosure is required because when asserting diminished capacity, the defense “must obtain a corroborating expert opinion and disclose that evidence to the prosecution pretrial,” giving the State a reasonable opportunity to decide whether to obtain its own evaluation “[depending on the strength of the defense’s showing.” Id. (citing CrR 4.7(b)(1), (b)(2)(viii), (g); In re Pers. Restraint of Hutchinson, 147 Wn.2d 197, 204, 53 P.3d 17 (2002)). Diminished capacity evidence is thus distinguished from observation testimony about relevant facts tending to rebut the State’s mens rea evidence because diminished capacity requires an expert diagnosis of a mental disorder and expert opinion testimony connecting the mental disorder to the defendant’s inability to form a culpable mental state in a particular case. Atsbeha, 142 Wn.2d at 918.
¶21 Clark first contends that he was not required to plead diminished capacity because Dr. Oneal’s expert testimony was not actually diminished capacity evidence. The record indicates otherwise. Even though trial counsel rejected the diminished capacity label, the primary intended purpose for Dr. Oneal’s testimony in this case was to rebut the State’s mens rea evidence on the basis that Clark’s clinically evaluated intellectual deficits impaired his ability to understand and assess the risks of his behavior, thereby reducing the likelihood that Clark acted with a culpable mental state when he shot D.D. As the trial court appropriately recognized, that is precisely the purpose of diminished capacity evidence. See, e.g., id.; State v. Greene, 139 Wn.2d 64, 73-74, 984 P.2d 1024 (1999). The label that trial counsel attaches to its proffered evidence cannot change the actual purpose for which the evidence is offered. Cf. Cienfuegos, 144 Wn.2d at 227-28 (considering evidence regarding the defendant’s ability to form the requisite mental state as evidence of diminished capacity even though trial counsel *652did not request a diminished capacity instruction). It is clear from the record that the actual purpose for Dr. Oneal’s expert testimony was to establish Clark’s diminished capacity.7
¶22 Clark also argues that Dr. Oneal’s testimony was not diminished capacity evidence because Dr. Oneal would not have testified that Clark “lacked the capacity or ability to form the requisite mens rea.” Pet. for Review at 15. This argument shows only that even if Clark had pleaded diminished capacity, Dr. Oneal’s testimony might still be inadmissible because it did not meet the relevancy threshold. It does not change the purpose for which the evidence was offered. And while Clark argues on review that we should relax the relevancy threshold for expert testimony of diminished capacity, he does not show it is incorrect or harmful. See W.G. Clark Constr. Co. v. Pac. Nw. Reg’l Council of Carpenters, 180 Wn.2d 54, 66, 322 P.3d 1207 (2014). Our diminished capacity precedent merely sets forth a specific application of the general standard that expert testimony must be relevant and helpful to the trier of fact, which does not contravene a defendant’s constitutional right to present evidence in his or her own defense. ER 401, 402, 702; Jones, 168 Wn.2d at 720; Atsbeha, 142 Wn.2d at 917-18. Moreover, a relaxed relevancy threshold for diminished capacity evidence would not change the fact that Clark did not plead diminished capacity in this case.
¶23 Clark argues in the alternative that we should treat trial counsel’s failure to assert diminished capacity as merely a “pleading failure” that did not warrant exclusion of Dr. Oneal’s testimony. Suppl. Br. of Pet’r at 16 (boldface omitted). However, on this record, the failure to assert diminished capacity was unquestionably a purposeful decision by trial counsel. That purposeful decision has conse*653quences because while the State is always required to prove the defendant’s actual culpable mental state, it is not automatically required to prove the defendant’s capacity to form a culpable mental state; such capacity is presumed unless the defendant places it at issue. State v. Johnson, 150 Wn. App. 663, 671, 208 P.3d 1265, review denied, 167 Wn.2d 1012, 220 P.3d 208 (2009). If the defendant does not place his or her capacity at issue but is still allowed to present expert testimony intended to negate such capacity, the State has no way to meaningfully respond and the jury is left to evaluate an expert opinion with no context for assessing its relevance to the elements of charged offenses.
¶24 We do not question the principle that a criminal defendant has the constitutional right to present evidence in his or her own defense, and relevant observation testimony tending to rebut any element of the State’s case, including mens rea, is generally admissible. However, expert opinion testimony that a defendant has a mental disorder that impaired the defendant’s ability to form a culpable mental state is, by definition, evidence of diminished capacity. And where, as here, the defense does not plead diminished capacity, such testimony is properly excluded.
2. Dr. Oneal’s testimony was not admissible to explain Clark’s affect during testimony
¶25 In addition to rebutting the State’s mens rea evidence, the defense contends that Dr. Oneal’s testimony should have been admitted for the purpose of explaining Clark’s unusually flat affect while testifying. We do not rule out the possibility that expert testimony regarding a defendant’s mental disorder may be introduced for purposes other than establishing diminished capacity, and admissibility for one purpose is not necessarily determinative of admissibility for another. Atsbeha, 142 Wn.2d at 917 (admissibility of expert testimony, including testimony about a defendant’s mental disorders, is determined according to *654the Rules of Evidence). However, Clark does not point to anything in Dr. Oneal’s proposed testimony that would have helped the jury understand Clark’s unusual affect, or that would even support the proposition that Clark had an unusual affect. To the contrary, Dr. Oneal described “Clark’s participation, motivation, focus, [and] effort” as being “entirely within normal limits.”8 2 VRP (Oct. 4, 2012) at 276. The jury had the ability to evaluate Clark’s affect to the same extent it had the ability to evaluate the affect of every testifying witness, and Clark has not shown that Dr. Oneal’s expert testimony would have been helpful for that purpose.
B. Ineffective assistance of counsel
¶26 Clark contends he received ineffective assistance of counsel because trial counsel did not object when the State was allowed to inform the prospective jurors that it was not seeking the death penalty. Assuming that Clark’s trial counsel performed deficiently, he does not show prejudice as required by Strickland v. Washington, 466 U.S. 668, 687, 104 S. Ct. 2052, 80 L. Ed. 2d 674 (1984), and thus cannot establish ineffective assistance of counsel. Hicks, 163 Wn.2d at 486-89; State v. Townsend, 142 Wn.2d 838, 846-49, 15 P.3d 145 (2001).
¶27 Considered in the full context of the case, Clark does not show that the State’s remarks and the defense’s failure to object were “sufficient to undermine confidence in the outcome.” Strickland, 466 U.S. at 694. The jury was repeatedly and properly informed of its duties, and we presume it followed those instructions. Id. at 694-95. When the court made preliminary remarks to the jury panel, it reminded them that they would be expected to “accept the instructions of the court” and “base any decision upon the law and the facts uninfluenced by any other consider*655ations.” 5 VRP (Mar. 13, 2013) at 370. After the jury was selected, the court again reminded them their evaluation of the case must be “based solely on the evidence and my instructions on the law ” Id. at 493. And the court’s instructions on the law properly informed the jury that “[y]ou have nothing whatever to do with any punishment that may be imposed in case of a violation of the law. You may not consider the fact that punishment may follow conviction except insofar as it may tend to make you careful.” CP at 277.
¶28 There is no indication that the jury disregarded its instructions or paid less attention to the evidence presented throughout Clark’s trial because it was told that the death penalty was not at issue. Cf. State v. Kalebaugh, 183 Wn.2d 578, 586, 355 P.3d 253 (2015) (rejecting the possibility that a trial court’s “offhand explanation of reasonable doubt at the beginning of this case” harmed the defendant in light of the fact that the jury was repeatedly and properly instructed on reasonable doubt and the presumption of innocence). There is also no reason to believe that a contemporaneous objection by defense counsel would have reduced any potential for prejudice more than the court’s proper, written instructions did. We thus hold that Clark has not carried his burden of showing prejudice and therefore has not established ineffective assistance of counsel.
C. Cumulative error
¶29 Clark does not show any error, so the cumulative error doctrine does not apply. Coe, 101 Wn.2d at 789.
CONCLUSION
¶30 Expert testimony that a defendant suffered a mental disorder not amounting to insanity that impaired the defendant’s ability to form a culpable mental state is diminished capacity evidence. The trial court correctly recognized that and properly excluded Dr. Oneal’s expert *656testimony because Clark did not assert or plead diminished capacity or show that Dr. Oneal’s testimony was otherwise relevant. We therefore have no reason to revisit Atsbeha’s three-part test for determining whether expert testimony of diminished capacity is admissible in accordance with the Rules of Evidence. Moreover, the court properly allowed relevant observation testimony, which the defense relied on in its attempt to rebut the State’s mens rea evidence. Clark does not otherwise show reversible error. We therefore affirm.
Johnson, Stephens, Wiggins, and González, JJ., concur.We use the victim’s initials because he was a minor at the time of his death.
Miranda v. Arizona, 384 U.S. 436, 86 S. Ct. 1602, 16 L. Ed. 2d 694 (1966).
The record contains inconsistent spellings of this expert’s last name. See, e.g., Clerk’s Papers at 25 (“O’Neal”), 56 (“Oneal”). We use the spelling “Oneal” for consistency with the Court of Appeals opinion. State v. Clark, No. 45103-4-II, slip op. at 3 (Wash. Ct. App. June 23, 2015) (unpublished), http://www.courts.wa.gov /opinions/.
The defense did not elicit testimony that one of Clark’s neighbors perceived him as slow, believing that was outside the scope of the court’s written ruling. Whether the written ruling was unduly restrictive and whether trial counsel was ineffective for failing to elicit testimony about Clark’s perceived slowness are not raised as issues on appeal.
The court did not impose a sentence for the first degree felony murder conviction due to double jeopardy concerns. VRP (May 28, 2013) at 7.
The State did concede on appeal that the trial court erred in instructing the jury on an uncharged alternative means for first degree robbery. Clark, No. 45103-4-II, slip op. at 14-16. The Court of Appeals accepted the concession and reversed the robbery conviction because the error was not harmless. Id. at 16. That issue is not presented for our review and does not affect our analysis.
We therefore need not look to cases from other jurisdictions analyzing the admissibly of expert opinion testimony offered for purposes other than establishing diminished capacity. See, e.g., State v. Burr, 195 N.J. 119, 948 A.2d 627 (2008). To the extent Clark argues there were other purposes for Dr. Oneal’s testimony, we address that issue below.
Notably, the trial court stated that it did not notice anything particularly unusual about Clark’s affect while he was testifying. 14 VRP (Apr. 16, 2013) at 1795. We are in no position to second-guess that observation.