Opinion by
Judge PLANK.Defendant, Robert Lanari, appeals the judgment of conviction entered on jury verdicts finding him guilty of first degree murder, attempted first degree murder, and four counts of violent crime. We affirm.
Defendant and his wife separated in March 1986, causing defendant to become distraught. After the separation, the wife established an intimate relationship with a man who was also one of defendant’s best friends.
One morning the following June, defendant’s wife told him of her relationship with the friend. This revelation increased the defendant’s distress, and he arranged to meet with the friend and his wife at the friend’s house that evening. A short time after the meeting began, defendant drew a weapon and shot the friend and his wife. The friend’s wound was fatal.
Defendant claims that certain actions taken at the meeting between his wife and the friend angered him and caused the shootings. And, consonant with this claim, defendant, prior to trial, endorsed a psychiatric witness to testify about, among other things, heat of passion manslaughter. However, the trial court granted the People’s motion to strike the psychiatrist as a witness. In granting the motion, the trial court determined that heat of passion manslaughter can be readily understood by a jury and, consequently, that an expert witness is unnecessary and usurps the decision-making role of the jury.
I.
Defendant maintains the trial court erred in striking the witness. We disagree.
Expert testimony is not admissible to explain matters within the experience and common knowledge of jurors and the determination whether expert testimony will aid the jury in resolving an issue is a matter within the sound discretion of the trial court. People v. Beaver, 725 P.2d 96 (Colo.App.1986).
Here, the issue was whether defendant acted out of a sudden heat of passion which was caused by “serious and highly provoking acts” of wife and decedent that were sufficient to excite “an irresistible impulse in a reasonable person.” See § 18-3-104, C.R.S. (1986 Repl.Vol. 8B). The trial court implicitly concluded that the factual and legal issues were of such a nature that the jury was competent to draw the correct conclusions.
We agree that the subject matter of irresistible impulse and heat of passion is not beyond the ken of the average layperson. Accordingly, the trial court did not abuse its discretion in excluding the psychiatrist from testifying. See People v. Lawson, 37 Colo.App. 442, 551 P.2d 206 (1976); McCormick on Evidence § 13 (E. Cleary 3d ed. 1972).
II.
As part of its pretrial discovery, the People interviewed the psychiatrist. During cross-examination and over defense counsel’s objection, the People repeatedly impeached defendant with inconsistent statements that he had made to the psychiatrist. Defendant claims that since the psychiatrist did not testify, the use of such statements violated both his Sixth Amendment right to effective assistance of coun*401sel and his attorney-client privilege. We disagree.
Under certain circumstances, exclusion of statements made to experts or their statements is justified under either the Sixth Amendment right to effective assistance of counsel, Hutchinson v. People, 742 P.2d 875 (Colo.1987), or the attorney-client privilege, Miller v. District Court, 737 P.2d 834 (Colo.1987).
Here, two factors militate in favor of the use of the statements for impeachment. First, the statements were provided to the People under Crim.P. 16 and, thereby, lost their confidential nature. Second, even if defendant’s statements made to the psychiatrist were protected as part of his Sixth Amendment right to effective assistance of counsel, or as part of his attorney-client privilege, since his trial testimony contradicted those statements, those statements could be used to impeach him.
Generally, defendant’s prior inconsistent statements, even if obtained in violation of the Constitution so as to be inadmissible in the prosecution’s case-in-chief, are admissible to impeach a defendant’s testimony. United States v. Havens, 446 U.S. 620, 100 S.Ct. 1912, 64 L.Ed.2d 559 (1980); Oregon v. Haas, 420 U.S. 714, 95 S.Ct. 1215, 43 L.Ed.2d 570 (1975).
We further hold that if, as here, the prosecution has discovered defendant’s statements to experts under Crim.P. 16, use of such statements to impeach a defendant after he has testified does not violate the attorney-client privilege.
A defendant’s right to testify does not encompass a right to commit perjury. Furthermore, the interest of the state in the truth seeking process outweighs defendant’s constitutional privilege interest in protecting such statements. See People v. Cole, 195 Colo. 483, 584 P.2d 71 (1978).
Therefore, we conclude that the trial court did not err when it permitted cross-examination of defendant concerning his statements to the psychiatrist.
III.
Defendant next argues that the trial court erred in not submitting to the jury his tendered instructions that further defined the trial court’s “heat of passion manslaughter" instruction. The language in the court’s heat of passion manslaughter instruction was properly based on § 18-3-104(1)(c), C.R.S. (1986 Repl.Vol. 8B) and COLJI-Crim. No. 9:08 (1983), and is susceptible to general understanding by persons of common intelligence and need not be further defined. See People v. Deadmond, 683 P.2d 763 (Colo.1984). The instructions as a whole adequately informed the jury as to the offense. Accordingly, the trial court’s decision not to further define the instruction was not erroneous. See People v. Deadmond, supra.
IV.
Defendant next argues that, since there was not a separate instruction for crime of violence, his conviction thereon must be set aside. We disagree.
Here, the verdict form required a finding concerning the use of a deadly weapon on the crime of violence charge.
Although we agree that it would have been better to set out the exact elements of the crime in a separate instruction, we determine that the instructions as a whole were adequate, see Brunner v. Horton, 702 P.2d 283 (Colo.App.1985), and required the jury to determine that defendant used a gun. We also note that it is uncontested that defendant brought a weapon to decedent’s home, shot the friend three times, and shot his wife once.
The others issues raised by the defendant are without merit.
Judgment affirmed.
REED, J., concurs. DUBOFSKY, J., dissents.