Jail officials say that a US citizen suspected of being an al-Qaeda conspirator displays no serious symptoms of mental problems.
Jose Padilla was arrested at Chicago airport in May 2002
Jose Padilla, a 36-year-old Muslim convert, has been in military custody in South Carolina for the past three-and-a-half years.
Last week a psychiatrist for his defence said he was mentally unfit to defend himself in court.
A hearing in Miami is sitting to rule whether Mr Padilla can stand trial.
Craig Noble, the US Navy prison's main psychologist said he examined Mr Padilla when he first arrived in June 2002 and again in May two years later.
Apart from the fact that Mr Padilla had begun to wear glasses, Mr Noble said he found the second visit "unremarkable" for any signs of problems.
"He was responsive, made good eye contact, in fact smiled frequently," Mr Noble told the hearing.
He was testifying on the third day of the hearing.
Two experts hired by Mr Padilla say he is suffering from post-traumatic stress disorder and cannot take part in his own defence.
They say isolation and torture have caused his psychological ill health.
US officials deny that he was tortured.
The prison's technical director Sanford Seymour gave new evidence regarding two of Mr Padilla's claims of ill treatment.
Mr Seymour said the "noxious smell" Mr Padilla complained of in fact came from a paper mill less than a mile (1.5km) away from the prison.
He also said that Mr Padilla was injected with a flu vaccine and not LSD as had been claimed.
Mr Padilla is due to be tried in April along with two co-defendants.
He faces life in jail if convicted of plotting to murder, kidnap and maim persons in a foreign country.
Other charges against him allege he was part of a North American terror cell that provided support to radical Islamists around the world.