Final answer:
Among Allport's principal ingredients for positive intergroup contact, intergroup competition is not included. His theory suggests that equal status, common goals, and personal interactions are important, whereas competition may actually exacerbate tensions.
Step-by-step explanation:
All of the following are among Allport's principal ingredients for positive intergroup contact except intergroup competition. Gordon Allport, a prominent psychologist, theorized that positive intergroup interactions are more likely to occur under certain conditions. The conditions that facilitate such positive interactions include equal status among the groups, common goals, and opportunities for personal interaction. However, intergroup competition is not considered a principal ingredient for positive contact according to Allport's theory. In fact, intergroup competition can often lead to increased tensions and conflict, whereas cooperation and shared objectives help reduce intergroup prejudice and promote understanding.