Soundings were also taken on attitudes to the two main campaigns, Yes Scotland and Better Together.
Of those who are aware of the campaigns, 33% think Yes Scotland demonstrates the best evidence to support its case, compared with 32% for Better Together.
The findings come a week after Ipsos Mori suggested support for independence stands at 30% compared with 58% for the Union.
Earlier this month, a TNS-BMRB poll suggested support for independence is 28% while opposition stands at 53%.