Speaking to US news show Good Morning America (GMA), the anonymous juror said the Aquaman star had been given bad advice by her legal team.
Two weeks ago, a jury in Fairfax County, Virginia, found a 2018 article that Heard wrote for the Washington Post about her experiences as a survivor of domestic abuse to be defamatory.
In her first television interview to NBC Today, which aired in two parts on Tuesday and Wednesday, she said she did not blame the jury for viewing her and her former partner as “Hollywood brats” but insisted she had “no bad feelings or ill will” towards Depp.
The actor consistently denied during his own evidence the “outrageous, outlandish” claims of abuse and said he had “spoken up for what I have been carrying on my back reluctantly for six years”.
The 59-year-old was awarded 10.35 million US dollars (£8.2 million) in damages.
Following the trial, judge Penney Azcarate ruled that the identities of the seven jurors would remain secret for at least one year.
Speaking about Heard’s testimony, the juror told GMA: “It seemed like she was able to flip the switch on her emotions.
“She would answer one question and she would be crying and two seconds later she would turn ice cold.
“It didn’t seem natural.”
Depp by contrast, he added, “just seemed a little more real in terms of how he responded to questions”.
The juror also said there had been inconsistencies with Heard’s testimony about her use of make-up, and that the arguments over her charitable donations were “a fiasco” for the actress.
The six-week trial saw Heard challenged over why she had not yet donated her seven million dollar (£5.7 million) divorce settlement to charities as promised.
The juror said that Heard’s legal team “had sharp elbows versus being sharp”.
“They would cut people off in cross (examination) because they wanted one specific answer without context,” he said.
“They were forcing people to just answer a very narrow question… which was obvious.
“She needs better advice.”