Witnesses before the Confidential Committee of the Child Abuse Commission said there was a daily possibility of being abused for little or no reason.
Ms Justice Mary Laffoy's third interim report reveals the extent of abuse.
"All of the witnesses were clear that much of the time they did not know why they were being beaten," the inquiry's former chairperson said in her final interim report, which was published yesterday.
However, the Child Abuse Commission has decided to withhold publication of a separate report on the testimony of 340 witnesses who have recounted allegations of child abuse to the Confidential Committee. Ms Justice Laffoy said the decision not to publish the completed report at this time had been taken on legal advice.
The report documents the evidence given by 340 witnesses who completed their period of care before 1960. Priority was given to these former residents of institutions due to their age six witnesses were aged over 85.
Under legislation, the committee heard details of a person's experience of abuse in residential institutions in a private, informal manner.
However, it does not inform anyone or any institution that is the subject of such allegations. In addition, no party is allowed to be identified in any report compiled by the committee and it can only make findings of a general nature.
It is understood, the completed report contains detailed information on the circumstances of the witnesses before, during and after their admission to the care of institutions.
"The commissioners were impressed by the capacity of the majority of witnesses to give clear accounts of their experiences," said Ms Justice Laffoy.
Three out of 10 witnesses said their main reason for appearing before the committee was to help prevent abuse in the future.
More than 770 witnesses have already recounted their tales of abuse before the committee, while a further 319 are due to have their cases heard before the committee concludes its work in May 2005.