The association has long defended the profession’s activities as well as itself against critics who have questioned whether the organization helped make it easier for psychologists to remain involved with the government’s interrogation program, even after the Abu Ghraib scandal set off a public debate about the program.

In its statement, the association said that its decision to appoint an independent reviewer was prompted by questions raised about the relationship between the psychological profession and the government agencies involved in the torture program in the new book, “Pay Any Price: Greed, Power and Endless War,” by this reporter.

The book uses the email archive of Scott Gerwehr, a behavioral researcher with ties to the C.I.A. and other agencies who died in 2008, to provide a glimpse at the network of psychologists, academic researchers, contractors and intelligence and Pentagon officials who formed the behavioral science infrastructure that grew up after the Sept. 11, 2001, terrorist attacks to support the Bush administration’s war on terror.

Most notable, the emails reveal that after the Abu Ghraib scandal broke in 2004, the association was eager to get out in front of the controversy by developing new professional guidelines for psychologists involved in interrogations. The group created a committee to study the matter, and in 2005 issued a report that, in effect, enabled psychologists involved in the Bush interrogation program to continue. A number of psychologists and human rights advocates have been critical of the work of that committee, known as the PENS Task Force, ever since.

Mr. Gerwehr’s emails show for the first time the degree to which behavioral science experts from within the government’s national security apparatus played roles in shaping the outcome of the A.P.A. task force. The emails show that in July 2004, just months after the graphic photos of abuse at Abu Ghraib were publicly disclosed, association officials convened a private meeting of psychologists who worked at the C.I.A., the Pentagon and other national security agencies to provide input on how the association should deal with the “unique ethical issues” raised for psychologists in the wake of the Abu Ghraib disclosures.

After the A.P.A. task force effectively endorsed the continued involvement of psychologists in the interrogation program, one association official wrote, in an email on which Mr. Gerwehr was copied, that he wanted to thank an intelligence official for helping to influence the outcome of the task force. “Your views were well represented by very carefully selected task force members,” the A.P.A. official wrote.

The association’s statement suggested, however, that Mr. Hoffman’s investigation would range far more widely than the relatively narrow questions raised by Mr. Gerwehr’s emails detailed in the book.