A psychiatrist who saw John W. Hinckley Jr. a dozen times before Hinckley shot President Reagan told a federal jury yesterday that the young man described himself as a "great planner and dreamer" who was left with "two obsessions in life"--his writings and the young actress Jodie Foster.

Hinckley saw himself as "the least successful person in a family of successful persons," unable to meet the expectations of his parents, psychiatrist Dr. John J. Hopper testified. Three weeks before the shooting, Hopper said, he saw the Hinckleys for the last time, after a frantic call for help from their son, who said he was stranded in New York.

"At that time I did not feel that then there was as much concern as I guess we all realize we should have had," Hopper told the jury during the fifth day of testimony at Hinckley's trial on charges that he attempted to assassinate Reagan.

During cross-examination by the prosecution, Hopper said there may have been some "exaggeration or dramatization" in Hinckley's written description of his mental state and that his feeling were described more intensely in his writings than in interviews in Hopper's office.

Under questioning by assistant U.S. Attorney Roger M. Adelman, Hopper said that he did not believe that Hinckley was out of touch with reality or that he suffered from any other typical symptoms of mental disorder, such as suicidal thoughts, hallucinations or major episodes of depression.

However, Hopper also told Adelman that he believed Hinckley "had significant disturbing feelings about himself." Hopper was permitted to testify because Hinckley had waived the doctor-patient privilege of confidentiality for the purposes of the trial.

Hopper also testified on cross examination that he had told a psychiatrist for the prosecution that the "angriest" he ever saw Hinckley was when he said he hadn't received his family inheritance when his older brother and sister received their shares. Hopper said Hinckley was "worried" about not working but was only interested in employment as a writer.

Hopper had helped Hinckley's parents devise a plan for their youngest son to be out of the family house in suburban Denver and supporting himself by March 30--the day Reagan was shot. After Hinckley called from New York, saying that his parents would never see him again if they didn't bring him home immediately, Hopper testified, he advised the parents to wait because he was sure Hinckley could take care of himself. They did, for one day.

Two weeks later, Hopper told the jury, he received a get-well card in the mail, written in Hinckley's handwriting. The card, introduced into evidence yesterday, said: "Thanks for recommending that I starve in New York City."

"It was an expression of anger, albeit sarcastic, toward me that might have been fitting," Hopper testified.

Hopper, the only defense witness to testify yesterday, said he began seeing Hinckley in October 1980, after John W. Hinckley Sr. told him his son was having problems "sorting out his life." During more than five hours of testimony, Hopper said the younger Hinckley described recurring spells of anxiety and told of "a feeling of sadness and disappointment" about his frustrated efforts to make a living as a writer.

The defense is trying to persuade the jury that Hinckley was legally insane when he wounded Reagan, his press secretary, a U.S. Secret Service agent and a D.C. police officer. They contend that Hinckley, living in a fantasy world and infatuated with Foster, did it to gain the actress' attention.

The prosecution contends that Hinckley's attack on Reagan was a planned and deliberate act.

During the entire period that Hinckley was meeting with Hopper--from October, 1980, to February, 1981--it is undisputed that he bought guns, fired them in target practice, sent a note to the FBI threatening to kidnap Foster, traveled around the country and stalked Presidents Carter and Reagan. Hopper testified yesterday he never knew about any of those activities. He acknowledged that Hinckley's failure to mention those actions might cast doubt on portions of the diary that Hinckley kept.

According to Hopper's testimony, Hinckley first told him about Foster on Nov. 4, their third session together. Two months earlier, Hinckley had been to Yale University, where Foster was then a student, after he persuaded his parents to let him enroll in a writing course there.

Hopper said Hinckley told him he wanted to have a "relationship" with Foster and that he had tried to contact her at Yale but she had "turned him down." When Hopper asked Hinckley to write an autobiography for him, Hinckley described his month in New Haven as "a month of unparalleled emotional exhaustion."

"My mind was at the breaking point the whole time. A relationship I had dreamed about went absolutely nowhere. My disillusionment with EVERYTHING was complete," Hinckley said in the essay which was introduced into evidence yesterday.

"I have two obsessions in life now: writing, and the person we discussed on Nov. 4. I care about nothing else!" Hinckley wrote. Hinckley did not bring up Foster again, Hopper testified.

Hopper testified that when he met with Hinckley's parents that same month, their own differences about "how to deal with John" became apparent.

Hinckley's father, a wealthy Denver oil executive, was "strict and authoritarian." His mother, Hopper said, took a more "permissive and protective stand."

When the Hinckleys expressed concern about their son's use of the tranquilizer Valium, and suggested that he be hospitalized in a drug treatment center, Hopper said he didn't think Hinckley's limited use of the drug was a problem. Hinckley himself "didn't say specifically" whether he wanted to be hospitalized, Hopper testified.

To help reduce Hinckley's use of Valium and control his anxieties, Hopper said he recommended a series of so-called "bio-feedback" treatments, in which a patient monitors his own muscle tension and other indicators of anxiety measured by electrodes and small thermometers. Hopper, calling the treatment a kind of "meditation," said patients can then learn how to calm themselves. Hinckley had five such treatments in his office, Hopper said, and was advised to do other exercises at home to deal with tension.

As part of that treatment, Hinckley kept a diary in which he recorded his feelings in situations he had described as stressful, such as walking through a crowded shopping center, Hopper testified.

On Jan. 29, two months before the shooting, Hinckley wrote in the diary, ""I try and try for normalcy. Believe me, I try!"

At the end of January, when Hinckley was faced with the plan that he be out of his family home by March 30, Hopper said he expressed a "hopefulness and a willingness to try" but that it was also "apparent that it stressed him."