Abstract
<p>Large language models are increasingly used as writing partners, but their use complicates whether writers experience the resulting text as genuinely their own. Such psychological ownership is especially relevant in AI-assisted writing because it contributes to the immediate and extended experience of AI use, and users may sign, share, revise, or be held accountable for texts whose content was partly generated by AI. Prior work shows that greater human input can increase ownership, but it remains unclear how ownership is shaped by two common forms of involvement: steering generation through prompting, directly revising generated text, and their combination. We report a preregistered mixed factorial experiment (N=273) in which online participants wrote short stories either without AI assistance or with AI assistance under one of two prompting styles (single-prompt vs. iterative), crossed with editing or not editing the AI-generated text. Editing increased ownership, especially for single-prompt generation. Iterative prompting increased ownership when editing was unavailable, but not when editing was available. These findings suggest that iterative prompting and post-generation editing are partially substitutable routes to psychological ownership, each providing opportunities for control and self-investment at different phases of the writing process. Fully manual writing nevertheless produced substantially higher ownership than all AI-assisted conditions, a gap that persisted in exploratory covariate analyses adjusting for effort, perceived story quality, and intrinsic motivation. The results suggest that AI writing tools should avoid one-shot delegation workflows when ownership matters, and instead support users in both steering and directly revising co-created text.</p>