John W. Hinckley Jr. was calm and unemotional after his arrest for shooting President Ronald Reagan, complaining once on his way to D.C. police headquarters that the handcuffs on his wrists were too tight, a U.S Secret Service agent testified yesterday.

"He made no aggressie moves. He wasn't hostile in any manner. He obeyed our every command or wish that he spoke clearly and distinctly. He did not appear to be sleepy or drowsy or depressed," said Agent Carlton D. Spriggs, who was with Hinckley for a total of about an hour on the day of the shooting.

Spriggs was at the scene of the attack outside the Washington Hilton Motel. He told the jury that when he heard gunfire he drew his weapon but "I was unable to get a clear shot at the defendant."

Spriggs acknowledged that he told government psychiatrists that when he ran toward Hinckley "he appeared to be shocked, as if a whole crowd of people were coming on him and he was trying to protect himself."

But after the arrest, he told the jury, he saw nothing unusual about Hinckley's behavior or demeanor.

Hinckley watched Spriggs' testimony yesterday afternoon on closed circuit television from a small cell behind the courtroom. He was excused from the trial in late morning by Judge Barrington D. Parker, and he did not return to the courtroom.

Hinckley, who has left his trial on four other occasions since it began five weeks ago, grew increasingly restless during testimony yesterday morning about sophisticated X-rays that were taken of his brain. During the medical testimony, he tapped his fingers repeatedly on the defense table, removed his clip-on tie and after a recess, returned to his seat no longer wearing the vest to his tan three-piece suit.

With the jury outside the courtroom, Parker asked Hinckley if he wanted to be excused and if he had discussed the issue with his defense lawyers. Hinckley, in a weak voice, twice responded "Yes, sir." Later, Parker cautioned the jury not to draw any inferences "one way or the other" from Hinckley's absence, and the testimony proceeded without him.

Spriggs wsa the fifth witness called by the prosecution, which this week began its effort to convince the jury that Hinckley was sane at the time of the attack on Reagan. Hinckley claims he was legally insane at that time and should not be held criminally responsible for his acts.

Before it brings in its own psychiatric experts, the prosecution is relying on testimony from lay witnesses, like Spriggs, to show that Hinckley was rational and coherent after the shooting. Defense psychiatrists have testified that despite his mental illness, Hinckley would appear calm and responsive to ordinary observers.

Spriggs, told the jury yesterday that his Secret Service training included instruction on dealing with behavior of mentally ill persons. When questioned by Fuller, Spriggs was able to generally define the terms psychosis and schizophrenia, both of which are characteriszed by withdrawal from reality. Spriggs admitted during cross-examination that he was unfamiliar with psychiatric opinion that some psychotic persons appear in touch with reality.

FBI special agent Richard Qulia testified yesterday that Hinckley was "collected and intelligent" during the hours after the shooting, even asking if the Academy Awards, scheduled that night, would be postponed because the president was wounded. Parker allowed Qulia to testify yesterday after some debate about whether his testimony relied on information from a one half hour interview with Hinckley that Parker earlier ruled was obtained illegally.

In describing the chaotic shooting scene, Spriggs was unwilling to say that agents there were under stress. Spriggs told assistant U.S. Attorney Marc, B. Tucker that he had been under stress before, in 1972 and 1974, when he played professional football for the Dallas Cowboys.

"Did you beat the Redskins?" defense lawyer Fuller shot back, jumping to his feet. The jury, judge and spectators laughed heartily. It was an unusual break in a long day repeatedly interrupted by extended bench conferences, during which the jurors and spectators sat in silence while Parker conferred privately with the lawyers on both sides.

Most of what the jury heard yesterday was additional testimony about sophisticated computer enhanced X-rays, known as CAT scans, which revealed that folds and ventricles in Hinckley's brain are widened, indicating his brain was shrunken. The debate at the trial focused on whether those findings are normal and whether they are seen more frequently in schizophrenics than in normal people.

Dr David O. Davis, chief of radiology at George Washington University Hospital, testified at length for the prosecution yesterday, stating repeatedly that while he thought Hinckley's brains scans were unusual for a person of his age, the findings were otherwise insignificant. Hinckley was excused from court during Davis' testimony.

Davis said he disagreed with defense testimony from Boston radiologist Dr. Marjorie LeMay who had described findings on Hinckley's brain scans as "striking and definitely abnormal."

Davis, who said he has looked at 15,000 to 20,000 sets of CAT scans since the technology was first developed, dismissed various statistical studies about such brain changes as "meaningless and irrelevant" because they either relied on a small group of patients or used obsolete CAT scanners.