The Great Ape Dictionary

This is where we host our materials for the Great Ape Dictionary experiments. We take a community science approach to explore language-using humans understanding of the gestures used by modern ape species in order to investigate to what extend humans continue to have access to this shared system.

Participants were randomly allocated to two conditions: those who viewed gesture videos only (Video only), and those who viewed gesture videos with a brief, one-line description of context (Context). From a set of 40 videos, each participant saw 20 videos with examples of ape gesture (10 chimpanzee, 10 bonobo). Videos were cut to show only the gesture, eliminating any behaviour before or after communication. Video lengths ranged from 7-33 seconds and could be watched as often as required before the answer was selected. A 500-millisecond fixation point was presented in the centre of the screen prior to each gesture video, videos were presented together with a Bonobo-bot illustration to highlight the gestural action within each video, and four possible meaning answers. The one-line descriptive text in the Context condition was presented below the video.

We selected 10 gesture types for which we were previously able to confirm meaning in both chimpanzees and bonobos. Gesture meanings were originally established using the Apparently Satisfactory Outcome: the response by the recipient that stopped the signaller from continuing to gesture. Some gestures are used towards a single meaning, whereas others can be used towards two or more meanings. The correct meaning for a gesture video stimulus was assigned based on the specific meaning used for that instance of communication, rather than in general for that gesture type. We included a subset of gesture types that are employed flexibly by apes towards two or more meanings (‘Ambiguous gestures’: Chimpanzee n=4, and Bonobo n=3) within our dataset. For these gesture types we made the alternate meaning (incorrect in this specific instance of communication but which would be correct in other instances of the same gesture type) available as a possible answer to participants.

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