Complete the summary below with words taken from paragraph F.
Use NO MORE THAN THREE WORDS for each answer.

The prototype of the Japanese ‘face robot’ observes humans through a [1] which is planted in its head. It then refers to a [2] of typical ‘looks’ that the human face can have, to decide what emotion the person is feeling. To respond to this expression, the robot alters it’s own expression using a number of [3].