Previous studies have also examined motivations for specific types of knowledge-sharing activities, such as question answering. For instance, Raban and Harper  conducted a literature analysis and identified 14 motivations for answering questions online, and then grouped them into intrinsic and extrinsic categories. Similarly, Ringel Morris and colleagues  identified 10 motivations for answering questions asked on social networking platforms such as Facebook and Twitter: altruism, expertise, properties of the question, nature of the relationship, connecting socially, free time, social capital, obligation, humor, and ego.