Page 36 - Emotions through the eyes of our closest living relatives- Exploring attentional and behavioral mechanisms

Chapter 2
during testing. Only positive reinforcements (apple cubes) were used during training and testing, and each bonobo (including ones that were not tested) received a reward equivalent to the reward of the bonobo being tested. Non-participating bonobos were distracted by the animal keeper who conducted a body-part training task used for veterinary purposes.
Equipment
The experiment was conducted using Presentation (NeuroBehavioralSystems) on an Iiyama T1931SR-B1 touchscreen (19”, 1280x1024 pixels, ISO 5ms) encased in a custom-made setup (Figure 1). To limit exposure to the experimenter, rewards for correct responses were automatically distributed using a custom-made auto-feeder apparatus that dropped apple cubes into a funnel that ended underneath the touchscreen for the bonobo to grab. A camera was placed outside the enclosure to film the bonobos while performing in the experiment.
Figure 1. Abstract representation of the bonobo setup. The experimenter (right) controlled the experiment from behind the bonobo setup while a keeper (left) distracted the other bonobos. The experimenter was not visible and remained silent to the bonobos most of the time, but the experimenter would move to the side of the setup when an individual needed some encouragement to continue with the task. At the end of the task, the experimenter and caretaker would say “good job” to the participating bonobo to indicate the bonobo was done with the experiment for this day.
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