An advert aimed at persuading undecided female voters to reject Scottish independence has drawn fire from across the political spectrum, with critics describing it as "sexist" and "patronising" and some even saying it has convinced them to vote yes.

The advert, broadcast by the pro-union Better Together campaign, was first launched on Tuesday. Called The Woman Who Made Up Her Mind, the short film depicts a working mother talking in her kitchen about the referendum. She says that her husband, Paul, "will not leave off about it", while there are "only so many hours in the day" to make a decision. She refers to Alex Salmond as "that guy off the telly", whose promises about currency and oil wealth seem to her to be "too good to be true", before concluding that she will vote no to independence on 18 September.

The response of pro-independence campaigners on social media was fast and often very funny, with the hashtag #PatronisingBTlady trending on Twitter overnight and a variety of yes-oriented revamps of the original popping up.

On Wednesday, however, it seemed that the advert had attracted derision from less obviously aligned women. The former Liberal Democrat MSP Margaret Smith, a no voter, tweeted that it was "absolutely appalling. Apart from the ref[erence] to phones that could have been produced for the 79 referendum."

Sandra Grieve, former convener of the Scottish Liberal Democrats, told the Guardian that the advert had finally convinced her to vote yes.

"It was the straw that broke the camel's back. I was a very clear no," said Grieve, who was a member of the Scottish Constitutional Convention which developed the framework for devolution, "but I've been increasingly uncomfortable with what I experience as a condescending smugness from Better Together."

"When I watched it I felt like I'd been transported back to the 1950s. I found it really shocking that we would portray a woman in 2014 who didn't know the name of Scotland's first minister and left all her political thinking for her husband to do."

Grieve, who says she remains a committed liberal despite her switch to supporting independence, added: "The camera shots of her wedding ring seemed out of touch with the many social arrangements we enjoy in modern Scotland, and the subliminal message of 'staying together for the kids' made me feel a bit sick!"

The pro-independence group Women for Independence said it had been inundated with calls and emails from previously undecided women who felt that the advert was "insulting, old-fashioned and unrealistic".

Appealing to undecided female voters has been key for both sides of the referendum debate, with women substantially more likely not to have made up their minds. Defending the broadcast, the Labour MSP for Dumbarton, Jackie Baillie, insisted: "The views in our broadcast are the views of the many articulate and intelligent women we have spoken to on the doorstep. They realise that this is not a normal election, and the decision we take on 18 September is for ever and will affect our children and their children. So it is important we get it right."

Better Together insisted that the words spoken in the film had been taken verbatim from conversations on the doorstep with undecided women and from dozens of focus groups around the country.

Talat Yaqoob, an activist for Better Together's Women Together offshoot, said: "The woman [in the advert] is of course not representative of all women – no one woman is – and I think it has been unfairly distorted into an illustration of what the campaign thinks of women. I can confidently say that is not the case. I wouldn't be involved in such a campaign. Just a quick look on the website and we see thoughts from women academics, carers, students, doctors and lawyers.

"There is a diverse range of women involved in both sides of the campaign. All of them deserve a focus and stake in this debate. That includes those having a cup of tea and discussing their political thoughts in the kitchen, before they head to work."