There are some surprisingly objective tests for aphantasia - fmri shows it pretty clearly, but also imagining bright things causes iris to change in normal peop

There are some surprisingly objective tests for aphantasia - fmri shows it pretty clearly, but also imagining bright things causes iris to change in normal people but not in people with aphantasia. You could say that aphants just may not be trying enough - there are tests for that as well. But there is hope that in many people aphantasia is something that can be overcome, because it’s just a matter of a lack of a proper skill, or some sort of childhood trauma.