For the four weeks from 27 January to 23 February, Scottish sales decreased by 0.8% on a like-for-like basis compared with February 2018.
Food sales performed better, increasing by 2.6% compared to the same time last year, but still below the three-month and the 12-month averages.
Ewan MacDonald Russell, head of policy and external affairs at the Scottish Retail Consortium, said that growth in food sales could be a consequence of food price inflation, which currently sits at 1.6%.
He also suggested that negativity coming from the political world could be helping to cause the disappointing Scottish sales figures.
“Our concern is the drumbeat of negative political news is influencing shoppers’ decisions”, he said.
“Between Brexit uncertainty and news of further taxes and levies in the Scottish budget accord; consumers are understandably cautious about committing to spending.
“Politicians from all parties should be careful to keep their language temperate in coming weeks, and in particular, come together to thrash out a deal to avoid the risks of a disorderly exit from the EU. Doing so would be a positive step which should help to reassure nervous customers.”