Women do not vote as a bloc any more than men do.

Nevertheless, there is no mistaking the gender difference in the way voters respond to the question of Scottish independence. Repeated polling shows that independence is less popular among women than among men. It is a difference of degree rather than a wholesale gender divide, but it is a headache for Yes Scotland.

The latest survey from TNS BMRB echoes this long-running trend, showing that 30% of men intend to vote yes in the independence referendum, compared to 22% of women, while 45% of women intend to vote no compared to 39% of men.

That is a worry for the pro-independence campaign. Making independence more appealing to women could help it make the breakthrough it needs. The SNP's response has been to create the Alex and Nicola show, putting Deputy First Minister Nicola Sturgeon on the podium next to the First Minister at every press conference and launch.

The trouble is, that strategy does not appear to be working. Today's poll for The Herald shows that Ms Sturgeon, just like Mr Salmond, is less popular among women than among men. A quarter of men like her compared to 19% of women, a six point difference. This is better than Mr Salmond's showing (there is a gulf of 13 percentage points between men and women's liking for the First Minister) but it is an important one.

The problem with treating voters like a homogenous group according to a trait like gender or age is that they tend to see through it. Women who know the SNP is promoting Ms Sturgeon in a bid to make their message more palatable to females are liable to feel patronised. The SNP has of course tried another tack, making childcare for all three and four-year-olds the centrepiece of its manifesto for independence. This poll does not reflect any impact that pledge may have had, and it may have gone down well. Alternatively, women voters may feel the party is trying to woo them with an eye-catching short-term benefit to deflect them from the once-in-a-lifetime constitutional, philosophical and economic questions around independence. Many women will not benefit from it in any case.

While the pro-UK parties do not exactly fare well with women voters either, the problem for them is less marked. As they are ahead in the independence poll, low personal popularity ratings are less of an anxiety for them in any case.

Nevertheless, Scottish Labour have problems of their own, with 41% of voters not knowing who Scottish Labour leader Johann Lamont is, two years after she took the job, compared to 16% who do not know Ms Sturgeon and 6% who are unaware of Mr Salmond. That low visibility is no asset to the pro-UK campaign, but it could be disastrous for Labour's 2016 Holyrood hopes. The only comfort for them is that Ms Lamont scores more strongly among women than her rivals do.

Is not being liked worse than not being known? Possibly it is in a referendum, but neither Labour nor the SNP have much to boast about in this poll of unimpressed voters.