A consultant psychologist has been giving evidence in the trial of a former Celtic boys club manager.
Dr John Marshall said "people in authority" were more likely to be "successful in grooming" abuse victims.
He also told the jury at the High Court in Glasgow that it was common for victims to delay reporting abuse.
Jim Torbett, 71, from Kelvindale, Glasgow, denies sexually abusing four boys between June 1985 and August 1994.
Dr Marshall explained a term known to forensic psychology as "delayed disclosure" which he described as the period of delay between someone being sexually abused and reporting it.
He said it's "often the case" that people might "test the water" and speak to someone they trust first.
The witness added: "It has been shown if someone discloses to a family member or friend and they have a negative reaction to that disclosure or non-supportive or non-believing the individual can close down and delay disclosure for a longer period beyond that."
Advocate depute Sheena Fraser asked what might happen if the person received a positive reaction. Dr Marshall said: "They might be more likely to go to authorities to report the abuse".
He said generally people in authority are "more likely to be successful in grooming victims".
Mrs Fraser asked: "What do you mean by grooming?"
Dr Marshall replied: "Grooming would be the slow process of gaining trust of a child with the purpose of carrying out sexual abuse of them."
Mrs Fraser continued: "Would that be, for example, buying the child sweets?"
The witness replied: "Getting to know them, getting to know their interests, spending lots of time with them, buying them gifts."
He was asked about gender and how that could affect the "timing of disclosure".
Dr Marshall said research and clinical experience shows men experience "extreme levels of embarrassment and shame".
He said: "They also often report their sense of power or strength as a male should have been used to stop the abuse from taking place.
"They tend to think of the abuse as an adult male rather than how they were as a child and more vulnerable."
During cross-examination by defence QC Tony Graham, Dr Marshall said there were around a dozen studies involving men, but much more research about female victims of alleged sexual abuse.
He said that one study - carried out in Boston - was the only one involving sports coaches but they were "lumped together for analysis" with clergymen and family members as alleged perpetrators.
Mr Graham put to the witness that there would be "merit" in separating the different groups.
Dr Marshall replied: "Yes, it's possible there wasn't enough in the sample."
The trial before judge Lord Beckett continues.