This project used experiments to examine the cognitive processes that make human culture possible using experiments with autistic and typically developing (TD) people. Key variables recorded include experimental conditions, efficacy of tools and social interactions between participants. Human culture accumulates and increases in complexity over generations, building on what came before. This phenomenon, termed cumulative cultural evolution, generates ever-more efficient tools and technologies and has helped humans to spread across the globe, but its causes remain mysterious. Many animals have simple forms of culture such as tools, foraging methods and social rituals that spread through groups by learning, but the cumulative nature of human culture seems to be unique in the animal kingdom. Human culture accumulates and increases in complexity over generations, building on what came before. This phenomenon, termed cumulative cultural evolution, generates ever-more efficient tools and technologies and has helped humans to spread across the globe, but its causes remain mysterious. Many animals have simple forms of culture such as tools, foraging methods and social rituals that spread through groups by learning, but the cumulative nature of human culture seems to be unique in the animal kingdom. We will examine the cognitive processes that make human culture possible using experiments with autistic and typically developing (TD) people. The most widely accepted explanation for cumulative cultural evolution is that it relies on a set of three cognitive processes that are rare or absent in other animals but allow humans to learn from each other with great accuracy and so build upon cultural knowledge. First, imitation: the ability to copy the others' precise actions. Second, teaching, whereby knowledgeable individuals actively help others learn. This is thought by psychologists to require Theory of Mind (ToM), the ability to reason about what others know and so correct their ignorance. Third, social attention: engaging others to work together to achieve joint goals. To date, firm evidence for this hypothesis is lacking and different studies have produced contradictory results. As deficits in imitation, ToM and social attention are among the key features of autism, experiments comparing autistic and TD people can help determine whether these processes are needed for cultural information to be passed on and accumulate. We used experiments to test whether imitation, teaching and social attention are required for cultural improvements in tools of differing levels of complexity. In one experiment, we will set up "transmission chains" of TD people where the first person makes a tool from everyday materials without any guidance, the second person can learn from the first, and so on. In a third of the chains participants will be able to watch and imitate the previous person. In another third, each participant will remain as a teacher to help the next person and in the remaining chains participants will simply see the final product made by the previous person. We predict that simple tools will become more efficient across all the chains, but for more complex tools imitation and teaching will be necessary to generate improvements. A second experiment will use groups of autistic and TD children working in pairs to make tools over eight rounds, with one member of the pair being replaced by a new child after each round. We expected the autistic children to show less social attention and teaching, so compared to the TD children their tools should show little improvement over the rounds.

(1) Large-scale transmission chain experiments on typically developing adults (N=624 participants) comparing the performance of tools (paper boats and baskets made from pipe cleaners) made by people in the following experimental conditions: (a) Asocial learning: Participants had 10 opportunities to make a tool. (b) Social learning: Participants took part in groups of 10, in a transmission chain design (similar to Chinese whispers). In each group, participants had the opportunity to learn from the previous person(s) in the chain through either Emulation (inspection of previous tools); Imitation (observing participants making their tools) or Teaching (participants provide instruction to later people in the chain. (2) Replacement experiments using groups of children with Autism Spectrum Disorders and Typically Developing children. In both ASD and TD groups, pairs of children worked together to produce a tool. At each round over a series of eight rounds, one participant was replaced with a new participant. Details of social interactions and the efficacy of tools produced were recorded.