Help! Regression analysis for a within-subject design


For an assignment I have, we are given of a set of real experimental data and a paper that was published on this study. It's a within-participant study, where it is essentially measuring correction as the outcome. There are 2 manipulations - context, medium. However, for each trial, the participant has to rate on a number of things such as confidence of their result, how much they like the stimulus, how realistic the stimulus was etc.

For one of the research questions, I want to see if how realistic they found the stimulus is related to how much they like it. (i.e., just comparing two ratings that were done every trial, but not considering the end results). I think a regression analysis would be suitable i.e. predicting their one's preference based on how realistic they found it. Is it okay to be running a simple regression analysis using these two variables for a within-participant design? I guess my question is do I need to collapse the data in anyway to address the fact that it's a within-participant design or can I just use all X number of trials there are, without even looking at which participant did which trials...

Any advice would be appreciated, thanks!