Hi, 

Is there an option to increase/decrease the anchor width without changing the amount of space available for the anchor text? 

In order to ensure that the anchor text does not overlap the anchor points, I have to increase the anchor width unnecessarily. 

Thanks in advance!

No, but save space for the anchor labels, you can break them into several lines:

<likert mylikert>
/ anchors = [1="Left
Anchor"; 2="Middle
Anchor"; 3="Right
Anchor"]
/ numpoints = 3
/ anchorwidth = 10%
</likert>