2.4.2. Test session in Experiment 1

Following session 7 of Experiment 1, we immediately conducted an observation test; in this, we determined if mice in the observation room paid attention to the other mice performing reaching behavior and compared the amount of time mice spent close to the slit the reaching room between the Learning and Unlearning groups (Tables 4 and and5).5). The next day of the test session, the pairs were changed. For Experiment 1, 16 cage mate and 16 non-cage mate pairs of observers and reaching mice were created. Furthermore, the reaching mice were observed once by both the Learning and the Unlearning groups. The combinations of the pairs are shown in Fig. 1 and Table 1.

For the observation test, we manually classified the behavior of the observer during reaching situations into three different categories using a previous study as a reference [1, 2]: “face to face,” “ambiguous,” and “not paying attention” (Fig. 2 and Fig. 3).

We measured the time required to complete a single spin before performing the reaching action in session 7 for the Learning group and the Unlearning group (Table 3). The starting point of the spin was the first frame in the video in which the mouse started spinning after sitting in front of the slit, and the end point was the frame before the one in which the front paws of the mice were away from the ground. We measured the time with a stopwatch.

The time spent close to the slit by the mice in the observation room during the test session was then calculated from the videos of the upper camera using the stopwatch (Fig. 4; Table 6). The observation room was divided into two regions, one on the side of the slit and the other on the opposite side of the slit, to determine if there was a difference in the time spent by the observing individuals in each region. The rate of the observer position was close to the slit was calculated by dividing the time spent near the slit by the total time of the experiment.