Religious institutions have divulged new information about abuse to the Child Abuse Commission which was not the subject of complaints from victims.
The chairman of the commission, Mr Justice Sean Ryan, made the revelation after confirming that the commission would not be naming individual perpetrators of abuse unless they had been convicted.
He also said alleged victims of abuse would be called to give evidence only to the extent that was necessary for the inquiry.
The dropping of Justice Mary Laffoy's policy of naming perpetrators of abuse, and the decision to sift complaints, have been strongly signalled since Justice Ryan took over the chair of the commission late last year.
He told today's hearing that a consultation process had elicited a general acceptance of his approach to these two issues.
Afterwards, at least three victims' groups were united in their disappointment at the dropping of the commission's power to name and shame.
However, John Kelly of the Survivors of Child Abuse welcomed the commission's decision to investigate the methods by which children came to be placed in institutions, including the role of the courts in committing many of them.
Justice Ryan has said that where there was a high level of co-operation from the religious it was unnecessary to hear a large number of witnesses.
He said complainants who were not heard at formal hearings before the investigation committee would have the option to transfer to the Commission's Confidential Committee.
Justice Ryan emphasised that this was not a consolation prize for somebody who had not made the cut for the investigation.