When searching in Articles, Books and More (any search scope/profile that includes results from the Central Discovery Index), you will see the Personalize option above the results. Users can set their discipline preferences. Records from the selected disciplines will appear before results from the other disciplines. It changes the ranking of results not the number of results.
Personalized choices are retained during the session for unsigned in users and guests and between sessions for signed-in users.
Personalizing Search Results (Ex Libris Knowledge Center)