JERUSALEM (AP) _ A Dutch psychologist said Monday that Holocaust survivors whose memories are failing after more than 40 years may have misidentified John Demjanjuk as the Nazi guard ''Ivan the Terrible.''

Willem Wagenaar, a defense witness at Demjanjuk's trial, said he noted evidence of ''memory problems'' in the testimony of five survivors who selected Demjanjuk's photograph from an eight-picture group.

''Look at the wording they used. They said: 'It looks like him, it reminds me of 'Ivan,''' said Wagenaar, from the University of Leiden.

''In my opinion the source of this uncertainty and imperfect accuracy is a memory problem,'' Wagenaar told the court.

Ukrainian-born Demjanjuk, 67, is charged with being a guard who operated gas chambers at the Treblinka death camp in Nazi-occupied Poland. About 850,000 Jews were killed at Treblinka in 1942 and 1943.

Demjanjuk, a retired autoworker who lived for 30 years in the Cleveland area before being extradited to Israel, claims he is a victim of mistaken identity.

Wagenaar said wrong identifications occur more frequently in cases of violent crime where the victim has vowed ''I will never forget that face.''

''If a lineup is composed in such a way as to point to the suspect, even completely innocent people can be identified by witnesses they've never seen before,'' he said.

The defense maintains the photo collection used in Demjanjuk's case was biased against the defendant because his picture was larger than the others and he was the only balding man shown.

Earlier Monday, the three-judge panel overruled an attempt by prosecutor Michael Shaked to block Wagenaar from testifying. Shaked said he objected to permitting psychologists to ''invade the area of witnesses.''

Demjanjuk's Israeli attorney, Yoram Sheftel, responded by saying Wagenaar would testify that the photos shown survivors were ''designed to mislead rather than stimulate memory.''