• extended assessment;
  • free-operant stimulus preference assessment;
  • multiple-stimulus without replacement;
  • response allocation

Top-ranked items were identified during 30-min free-operant preference assessments for 9 individuals. Data from each session were analyzed to identify the item (a) that was engaged with first in each session and (b) to which the most responding was allocated after 5 min, 10 min, 15 min, 20 min, and 25 min had elapsed in each session. The results indicated that the first-engaged item and the 5-min high-allocation item predicted the top-ranked item in 55% and 62% of the sessions, respectively. The results also showed that engagement with the top-ranked item from the first session decreased across subsequent sessions for 6 of the 9 participants. The implications of the results for brief versus extended stimulus preference assessments are discussed.