Unlike the capacitive touchscreens commonly used in smartphones, the touchscreens at the WKPRC work with infrared technology. The setup consists of two main parts: the touch frame that collects the ape’s manual input and the display that presents the experiment and which is mounted behind the touch frame. The touch frame is lined with light emitters and sensors that collectively form a grid of light beams in front of the display. When this grid is interrupted by an ape’s hand, the coordinates of this interruption are transmitted to the experiment software, which in turn decides what to present next on the display. The touch frame and the display are separated by a sturdy, transparent sheet of polycarbonate which allows strong touches while providing maximum safety at the same time.
Many of the chimpanzees, gorillas and orang-utans at the WKPRC have experience with touchscreen studies, and they get regular opportunities to participate in exchange for extra servings of their favourite foods. Many of our apes are “touchscreen pros” and have experience in a range of games. They include for example simple discrimination and categorization tasks in which the apes learn to distinguish pictures of cats from pictures of dogs. Some of our chimpanzees also have experience with serial learning tasks, in which they need to clear numbers or pictures off the screen in a correct order. Some other know how to coordinate with each other by playing a virtual ball back and forth between two touchscreens. Recently we have begun to provide our chimpanzees and orang-utans with rich and colourful virtual environments that they can navigate to find hidden virtual food. These touchscreen studies have given us valuable insights into how apes recognize pictures, what their natural preferences are, what their memory abilities are like and in which way they communicate.