Research across Britain has previously revealed that grouping by broad ability has no effect on pupils' attainment, but the majority of Scottish primaries appear to be disregarding the evidence in their drive to lift results.
The survey into setting and broadbanding, carried out by Lorna Hamilton of Edinburgh University, is beginning to show that schools have taken the advice of the inspectorate to heart and introduced setting at a far younger age.
The inspectors originally in-vited schools to consider setting in P6 and P7 but primaries have extended the practice in the last four years under pressure to raise attainment in core work.
First findings gleaned from local authorities suggest most schools will be using some form of grouping. But two authorities said their schools did not use setting as they were opposed to what they believed was its negative impact. They preferred broadbanding as a means of limiting ability.
Dr Hamilton told the Scottish Educational Research Association conference in Perth that setting and broadbanding are almost interchangeable terms.
Setting tended to be confined to narrower ranges of ability within a class whereas broadbanding may pull in top and upper middle pupils in one group and lower middle and low achieving in another.
Evidence from authorities indicates that pupils are divided after taking standardised or curricular tests. "People try to suggest that the testing is a simple measure of attainment and not of ability but people inevitably link the two together and have a hierarchical notion of what ability is.
"I think it reinforces the ideas of some kind of innate ability and intelligence and, in those terms, it seems to involve some limitation rather than potential. Does it lower expectations? And what about the impact on children in the lower groups? There is a disproportionate number of boys, pupils from ethnic minorities and pupils from lower socio-economic groups," Dr Hamilton revealed.
She suggested there could be long-term effects on the self-esteem of pupils in lower ability groups if they are divided early in primary. It could also reinforce social class divisions.
Local authorities, however, insist there are numerous benefits, not least for pupils who report positively on the experience. Less able pupils are said to do better because there is less anxiety. Pupils are able to concentrate more, although authorities are aware that lack of movement between sets may be a problem.
Councils say there is a strong impact on pupil performance. There is more direct and interactive teaching and staff are able to dictate the pace of learning. Differentiation is said to be easier. There is also less preparation for the teacher.
Setting further allows better tracking of progress, according to authorities.
One researcher - during questions - felt that primaries had been driven to setting by the national target-setting agenda. They improved results if they raised attainment of mid-ranking pupils.
A second stage of the study, backed by the Scottish Executive, is taking detailed evidence from 1,000 primaries.
SERA conference, 4 and 5