Hyperprosexia is a relatively uncommon term that is used to describe an intense state of concentration and focus on a particular subject or activity. Although there may not be many synonyms that describe this exact state, there are related terms that may be useful. For example, the phrase "single-mindedness" could be used to describe this type of focus. Another option might be "intense concentration," "deep absorption," or "extreme attentiveness." Although each of these phrases captures a slightly different aspect of hyperprosexia, they could all be used to convey a similar meaning. Regardless of which term you choose, the key is to convey the intensity and intensity of focus that is required for such an intense level of concentration.