I have two groups of users who rate on 7-point-scores for n data items. Now I want to test whether there is a difference in both groups in their error of central tendency, i.e.: does one group tend to rate more towards the middle of the scale than another?

I assume the ratings for one data item and both groups together to be distributed according to a normal. Can you recommend me the best test for this task? I don't know if an ANOVA is appropriate because it compares means, not variances within and between groups.

Thank you very much in advance,

Christian