Directions: Complete the following passage by using the words in the box. Each word can only be used once. Note that there is one word more than you need.

A．housed       B．simply       C．tie       D．stretch       E．return       F．fellow G．previously       H．sensitive       I．trapped       J．minimal       K．artificial

Rats and other animals need to be highly dependent on social signals from others so they can identify friends to cooperate with and enemies to avoid. To find out if this can 【小题1】 to non-living beings, researchers at the University of California tested whether rats can detect social signals from robotic rats.

They 【小题2】 eight adult rats with two types of robotic rat — one social ad one asocial. The robot rats were just like a chunkier version of a computer mouse with wheels to move around. During the experiment, the social robot rat followed the living rats around, played with the same toys and opened cage doors to let 【小题3】 rats escape. Meanwhile, the asocial robot 【小题4】 moved forwards and backwards and side to side.

Next, the researchers trapped the robots in cages and gave the rats the opportunity to release them by pressing a lever. The living rats were 52% more likely to set the social robot free than the asocial one. This suggests that the rats perceived the social robot as a genuine social being so that they may have a closer 【小题5】 with the social robot. This could lead to the rats better remembering having freed it earlier and wanting the robot to 【小题6】 the favour when they get trapped.

Rats have been shown to engage in multiple forms of mutual help and cooperation, including what is referred to as direct reciprocity where a rat will help another rat that has 【小题7】 helped them.

The readiness of the rats to befriend the social robots was surprising given their 【小题8】 designs. Researchers assumed that they’d have to give them moving heads and tails, facial features, and put a scent on them to make them smell like real rats, which turned out to be unnecessary.

The finding shows how 【小题9】 rats are to social cues, even when they come from basic robots. Similarly, children tend to treat robots as if they are 【小题10】 beings, even when they display only simple social signals. We humans seem to be fascinated by robots and it turns out that other animals are too.