THE independence debate is leaving voters in the dark by failing to focus on the decisive economic issues, according to a survey.

Results from ScotCen's latest annual Scottish Social Attitudes Survey suggest voters are more likely than ever to base their decision in September's referendum on whether they think independence will be good for the economy and their own wallet.

However, in an analysis of the findings published today, Professor John Curtice, of Strathclyde University, claims the debate is "short-changing" people by focusing on peripheral issues, such as EU membership.

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The survey found growing levels of confusion among voters "as a result of the apparent failure of the campaigns to focus on what matters most to voters," he warned.

Nearly two thirds of voters (64%) said they were "unsure" what would happen if Scotland became independent, up six points on the 2012 poll. Meanwhile, the number who felt "sure" about the consequences fell four points to 30%.

Fewer than a quarter of people questioned (22%) said they knew "a great deal" or "quite a lot" about independence.

The Scottish Social Attitudes survey, which questions about 1500 people each year, is seen as the most reliable measure of public views on issues, including independence, since devolution in 1999. Its latest poll, conducted between last June and October, produced stronger evidence than ever that the economy was the most important factor.

Asked how they would vote if they thought independence would make them £500 per year better off, backing for a split from the UK soared from 29% to 52%, while opposition fell to 30%.

By contrast, only 15% said they would back independence if they felt they would be £500 worse off, while 72% would vote No.

When the same question was put to voters in 2011, 65% said they would vote Yes if they thought they would be £500 better off.

Mr Curtice said this suggested "people now have to be even more convinced of the economic benefits of independence if they are to vote in favour".

He said arguments over Europe, welfare and currency, which have dominated the campaign, made "little difference" to how most Scots would vote.

He added: "The referendum campaign is at risk of short-changing the people of Scotland.

"So far it appears to have done little to help them be clear and confident about the decision they have to make.

"Voters want to hear about the economic and financial consequences of the choice they make, and it is on the outcome of that debate that the result of the referendum is likely to turn."

In a worrying sign for the Yes campaign, the survey suggested voters were more likely to take a pessimistic view of an independent Scotland's economic prospects. Only 9% agreed they would be personally better off if Scotland left the UK, against 29% who felt they would be worse off.

However, the 52% who believed independence would make no difference to their pocket suggested neither side had yet won the economic argument.

Posing the referendum question, support for independence rose from a record low of 23% in 2012 to 29% last year. However, the number who wanted Holyrood to take all the decision for Scotland fell four points to 31%.

Stripping out the 'don't knows' and 'won't' votes, 36% backed a Yes vote and 64% a No vote.

Deputy First Minister Nicola Sturgeon said: "This survey - carried out before the White Paper was published - shows significant movement in favour of independence. It also confirms that when we win the economic argument, we will win the referendum. "

However, Blair MacDougall, campaigns director of the pro-UK Better Together group, said: "This survey confirms what recent polls have shown - support for breaking up the UK remains below historic levels."

Scottish Labour's constitutional spokesman Drew Smith said: "We know from the Institute of Fiscal Studies that we would be £1000 worse off under independence while even [Finance Secretary] John Swinney admits in his private paper that he has doubts about whether we would be able to afford the state pension."