LoveFilm asked neuropsychologist Dr David Lewis, of Mind Lab International, to analyse the top ten films likely to put viewers in the "mood for love" on February 14.
He said that rom-com Love Actually is the film that is most likely to stimulate specialised neurons in the brain, called mirror neurons, that respond to witnessing the activity of others.
"So if an on-screen couple shares a passionate kiss, the mirror neurons in the viewers' heads will fire as if they were doing the kissing," he said. "They will experience the same powerful and pleasurable emotions that are being depicted on screen."
Love Actually puts around one in five people (21%) in a "loving mood", according to Dr Lewis.
He said that the interplay between various couples in the film gave audiences "multiple opportunities to empathise, while the challenges the characters overcome in the story increase the optimism viewers feel about their own relationships and their own romantic feelings".
The Notebook, a 2004 movie starring Ryan Gosling and Rachel McAdams, came next with 18%, followed - rather surprisingly - by Pixar animated feature Wall-E in third with 13%. The movie features two robot characters, but the mirror neurons can still sense the 'human' emotions behind the story, said Dr Lewis.
The ten films most likely to cause a romantic response are:
1. Love Actually (21%)
2. The Notebook (18%)
3. Wall-E (13%)
4. Notting Hill (9%)
5. Dirty Dancing (8%)
6. Ghost (5%)
7. Pretty Woman (4%)
8. Titanic (3%)
9. Jerry Maguire (2%)
10. Casablanca (1%)