Many modern interactions happen in a digital space, where automated recommendations and homophily can shape the composition of groups interacting together and the knowledge that groups are able to tap into when operating online. In this talk I will present two studies showing evidence that human and algorithmic behaviour interact together to produce emergent collective phenomena, such as positive vs. negative group performance. In the first study, group composition and modularity interact with search engines that people use to gather information online to solve real geopolitical forecasting tasks. In the second study, I use a hybrid transmission chain paradigm to show that social learning between machines and humans under uncertainty is limited, resulting in poor diffusion of innovations across a population.