The first date has been chosen to coincide with the Scotland versus Argentina rugby match at Murrayfield in Edinburgh, with the strikes continuing from up to and including Christmas Eve.
Further stoppages have been called for December 2-3, 9-10, 16-17 and 23-24.
The significant intensification of the long-running pay dispute, announced on Thursday afternoon, comes ahead of a meeting between the union and ScotRail on Friday.
It follows two one-day strikes which have brought almost the entire ScotRail network to a halt, including last Saturday.
A further revised offer was rejected by the union last week, which ScotRail said would have boosted wages for the lowest paid staff by 7.4 per cent.
However, RMT Scottish organiser Mick Hogg said: “We will not be taking any lectures from Jenny Gilruth.
"There is a meeting with ScotRail on Friday and if there is no solution, there will be complete havoc on ScotRail between now and Christmas.”
Services on only three ScotRail routes operated during the previous strikes on Saturday, and Monday, October 10, with hourly trains between Glasgow and both Lanark and Larkhall, and a half-hourly service between Milngavie, Glasgow, Bathgate and Edinburgh until early evening.
The dispute involves more than 2,000 staff, including train conductors and ticket examiners, catering workers, station and engineering depot staff, cleaners, supervisors and CCTV operators.
Last year, the RMT settled a seven-month pay dispute with ScotRail after months of Sunday cancellations, days before the start of the COP26 climate change summit in Glasgow in November.
The union had called 12 days of strikes to coincide with the United Nations’ Conference of the Parties conference.
ScotRail drivers’ union Aslef settled its pay dispute by accepting a 5 per cent offer in July after two months of disruption caused by drivers not volunteering for overtime on which the operator depends, with timetables cut by one third.
However, in an ongoing separate dispute involving Network Rail signallers and other staff, the RMT will be staging further three strikes across Britain which will again halt most ScotRail services this Saturday and next Monday and Wednesday – bringing the total to 12 since the summer.
Phil Campbell, ScotRail’s head of customer operations, said: "We’ve had no formal confirmation yet from the RMT, but if what is being reported is accurate, it is incredibly disappointing and will severely impact our customers, our staff and the economy in the lead up to Christmas.
“ScotRail made a significantly improved offer to the RMT, which would deliver a 7.4 per cent basic pay increase for the lowest paid, provide job security for at least six years, and increase allowances and commission payments. It’s time for the RMT bosses to give members a say and put it to a referendum.
“Once we have formal notification of any further action, we will assess the full impact of this strike action and will begin working on contingency arrangements. We will update customers as soon as this is complete."
Scottish Conservatives transport spokesperson Graham Simpson said: “The RMT has already brought misery to thousands of Scottish rail passengers over the last few months, now they seem hell-bent on ruining the nation’s Christmas with their selfish action.
“Not only would these strikes impact passengers trying to visit loved ones over the Christmas season, they would deal a hammer blow to small businesses in the middle of crucial festive trading.
“The RMT has been holding the country to ransom for too long. It’s appalling they are considering going ahead with these deeply damaging strikes.”
Martin Gallagher, a ScotRail passenger in Dunfermline, said: “This really is becoming farcical. Anyone who can afford to go on strike every week in the lead up to Christmas during the worst cost-of-living crisis in 40 years must already be extremely well paid.
"They are going to destroy their own jobs at this rate as this action drives more and more people away from trains for good."
A Scottish Government spokesperson said: “We absolutely respect the democratic right of union members to take industrial action and welcome the continued constructive discussions between ScotRail and the Scottish representatives of the RMT members. This collaborative approach is distinct from that taken elsewhere in the UK, particularly on the issue of minimum service levels.
“It is really disappointing, however, that union leaders continue to deny their members a referendum on the latest pay offer, one which would benefit lower paid ScotRail workers in particular. Even more disappointing is this latest threat of additional strikes in the lead up to Christmas particularly as this will not lead to any increased pay offer.
"If carried out, these strikes would potentially leave RMT members far worse off at a time when many will already feel the impacts of the costs crisis.”