Professor Tom Devine, Scotland's leading historian, said there had been a silent revolution within the Irish Catholic population since the 1970s, when people of that background were among the most hostile to devolution.
Professor Devine, author of the acclaimed The Scottish Nation and director of the Scottish Centre of Diaspora Studies at Edinburgh University, cited recent data from the Scottish Social Attitudes survey, which suggested those aligning themselves with Catholicism were both most supportive of independence and least fearful at the prospect of a Yes vote.
According to sociologist Dr Michael Rosie, a member of the Scottish Government's anti-sectarianism expert group, rather than the Social Attitudes survey revealing a shift in the "Catholic vote", it showed its near disappearance.
Speaking after an event on Scotland's Irish community during the St Patrick's Festival in Coatbridge, North Lanarkshire, Professor Devine said a reluctance among Catholics to embrace devolution in 1979 was a key reason why Home Rule polled so poorly in the west of Scotland.
There had been a radical departure, especially in the last 10 years, he said, which contradicted perceived wisdom. "There has been a silent revolution within the Irish Catholic population since the 1970s, the main reasons being the death of structural sectarianism and labour market discrimination," he said. "By the 1990s, people from the Catholic community had educational parity with other organised religions. That's vital. They are now much more confident in their Scottish skins."
John Curtice, professor of politics at Strathclyde University, said Professor Devine's point illustrated how voting habits among Scottish Catholics had changed. "It was certainly true in the 1970s that Catholics in Scotland were less inclined to vote for the SNP and therefore by implication less likely to vote for independence. At that point the concern among Catholics was that an independent Scotland might become a replication of Ulster," he said.
"The situation has changed significantly since then. Catholics are not particularly unlikely to vote for the SNP. However, I do think Catholics are generally still more likely to vote Labour than other people.
"The party who they do not vote for is the Tories. The SNP and independence are now as popular or as unpopular among Catholics as among the rest of the population."
In 1999's Social Attitudes survey, just 21% of Church of Scotland identifiers backed independence, compared to 34% of Catholics, and 31% of those of no religion. By 2012, 30% of Catholics supported independence, compared to 26% among those of no religion, and 17% among Church of Scotland identifiers.
Catholics were also "comparatively relaxed about the prospects of Scottish independence", with just 16% very worried, significantly fewer than the 26% of Church of Scotland identifiers.
However, Dr Rosie said attitudes towards independence were better explained "by experiences of secularisation rather than through hackneyed religious truisms".
Dr Rosie said: "Claims that Catholics are 'more likely' than others to support independence are rather superficial. When we factor in things like gender, class and age, the religious difference pretty much disappears altogether.
"This does not represent a shift in
'the Catholic vote'. It shows its near disappearance. Scotland's Catholics are not reducible to just their Catholicism, or for many their Irish heritage.
"They have many potential identities and whatever their Catholicism meant politically in the past, it has far less relevance today."
Labour MSP Siobhan McMahon added: "This is a highly debatable reading of the data and I'm surprised that any academic looks at the Catholic population as a homogenous group. It's about individuals and I doubt very much anyone will be voting along religious lines. People have left Labour, people have come to Labour. But this does little for the debate."
Former Glasgow MP George Galloway spoke recently of a "historic crossover between Scottish nationalism and anti-Irish-Roman Catholicism" and warned Catholic schools would be threatened by independence.