From Michael Huemer’s entry on “sense data”:http://plato.stanford.edu/entries/sense-data/ in the SEP.

bq. For instance, an overdose of LSD might cause me to have an experience of seeming to see a pink rat on this table, where there is in reality nothing pink-rat-like.

I was always told that was the kind of reaction you get to a _normal_ dose of LSD, and in an _overdose_ you end up in a coma with no sense data worth reporting. But maybe I should be deferring to those better informed!