While at a press conference for the show, the 78-year-old revealed that she had not been a fan of the series prior to becoming a member of the cast.
MacLaine, who plays Cora's (Elizabeth McGovern) mother Martha on series three of the show, told the audience that her hairdresser convinced her to take the part.
"That's basically why I did it, to see if my hairdresser lady was right," she said.
MacLaine went on to say that Downton Abbey is the perfect show for this day and age, despite being set in the early 20th century.
"What [creator] Julian [Fellowes]'s done so brilliantly is make 15 characters with just the right amount of time on screen, which fits with the internet tolerance for emotional knowledge," she quipped.
"A programme for attention deficit disorder," Fellowes added jokingly.
The creator recently addressed the issue of Dame Maggie Smith's departure from the series, saying it is entirely her decision.
Smith and MacLaine's scenes together this season are reportedly magical, according to star Joanne Froggatt.