psychiatric examination nor elsewhere that would show an incapacity on the witnesses] part to have observed the event to which his testimony related, or to recall that event sufficiently to testify accurately about it at trial’’); Bakken v. State, 489 P.2d 120, 124 (Alaska 1971) (explaining excluded evidence of witness’s alleged psychiatric problems would have been admissible if it was shown problem rendered witness’s observation and memory of event unreliable); Commonwealth v. Perreault, 13 Mass.App.Ct. 1072, 435 N.E.2d 635, 638 (1982) (" '[Tjhere must be some indication that the impairment or addiction involved is relevant to the issue of credibility before evidence of such can be used to impeach.' ” (citation omitted)); State v. Gum, 172 W.Va. 534, 309 S.E.2d 32, 43 (1983) (<HOLDING>). 3 . Many other courts also have concluded
holding witnesss mental histoiy irrelevant because witnesss present not past memory ability was the only relevant inquiry holding that evidence of witnesss acquittal by reason of mental illness was properly excluded partly because no showing was made that mental disorder affected witnesss credibility holding that a mental illness limitation limiting the maximum payment for care of mental illness or care of nervous conditions of any type or cause is ambiguous because the plan contains no definition or explanation of the term mental illness  and thus construed against the insurance company does not include physically based illnesses holding that a trial witnesss testimony as to the credibility of another witness was prejudicial error holding that a witnesss testimony or an exhibit may not explicitly and directly contain an opinion as to a trial witnesss credibility