Torture techniques used on suspected terrorists by the Bush administration may have failed to get to the truth, researchers say.

研究人员称，布什执政时期对恐怖主义嫌疑犯使用的拷问手段可能没有效果。

The extreme stress of torture harms the memory

Professor Shane O'Mara of Trinity College, Dublin, said the interrogation（审问，问号） techniques had a detrimental¹ effect（有害作用） on brain functions related to memory.

He listed 10 methods of what he called torture used by the US, including stress positions and waterboarding（水刑）.

His review is published in the journal, Trends in Cognitive² Science.

'Lack of control'

Professor O'Mara said US Department of Justice memos³ released in April showed that the Americans believed that prolonged periods of shock, anxiety, disorientation（方向知觉的丧失，迷惑） and lack of control were more effective than standard interrogation in extracting the truth.

He said: "This is based on the assumption that subjects will be motivated to reveal truthful⁴ information to end interrogation, and that extreme stress, shock and anxiety do not impact on memory.

"However this model of the impact of extreme stress on memory and the brain is utterly⁵ unsupported by scientific evidence."

He said studies of extreme stress with special forces soldiers had found that their recall of previously⁶ learned information was impaired⁷（受损害的） afterwards.

"Waterboarding in particular is an extreme stressor（紧张性刺激） and has the potential to elicit⁸（引出，抽出） widespread stress-induced changes in the brain."

Professor O'Mara said contemporary neuroscientific models of human memory showed that the hippocampus（海马） and prefrontal（前头叶的） cortices（树皮，外皮） of the brain were very important.

The stress hormone⁹, cortisol（皮质醇）, binds¹⁰ to receptors in the hippocampus and prefrontal cortex increasing neuronal excitability（神经元兴奋性） which compromises the normal functioning of the brain if it is sustained.

And other stress hormones¹¹ called catecholamines（儿茶酚胺） could lead to an increase in blood pressure and heart rate which could cause long-term damage to the brain and body if they were maintained at a high level for a long time.

Conditioning

Professor O'Mara said a common argument in favour of torture was that it would reliably elicit truthful information from the captive's long-term memory.

But psychological studies had suggested that during extreme stress and anxiety, the captive would be conditioned to associate speaking with periods of safety.

And because torture was stressful for the torturers the fact that the captive was speaking also provided a safety signal to the captor.

"Making the captive talk may become the end - not the truth of what the captive is revealing.

"These techniques cause severe, repeated and prolonged stress, which compromises brain tissue supporting memory and executive function.

"The fact that the detrimental effects of these techniques on the brain are not visible to the naked eye makes them no less real."