Is the dissociation a reaction to having to perform for/please your T by doing the assignment? or
A reaction to what you are reading about, an effort to not want to think about those things? or
A reaction to the expectation of looking within? or
A fear of looking within? or....
... in other words, explore the dissociation and learn about that as part of your assignment, too. What's it about? If you can identify it, possibly you can be relieved of it to do the reading and highlighting.