2.2. Design Experiment 2

The purpose of Experiment 2 was to evaluate which of the following factors influence the motivation of mice to observe the behavior of other individuals in Experiment 1: the movement intention of other individuals or the situation of the presence of other individuals, and the food table. Thirty male C57BL/N mice were prepared and randomly assigned to the Learning, Unlearning, and Empty groups, with ten animals in each group (Table 8). After three groups were trained to reach for food in the same way, the situations assigned to them in the test session were different as follows. The Learning group observed the reaching behavior of other individuals. The Unlearning group was placed in a situation where unlearned individuals were present in the training room. The Empty group was placed as the situation where the training room was empty.

Twenty animals were prepared for the demonstration of learned reaching or unlearned reaching in the reaching room in the test session (Table 9).

Forty animals (30 in three experimental groups; ten demonstrators for the test session) were trained in reaching behavior. Ten demonstrators of unlearned reaching were habituated as done in Experiment 1. After the training, the main data collection was conducted in a test session.

In the test sessions, the time mice spent close to the slit in the observation room was measured using the videos from the upper camera, and the rate of the observer position being close to the slit for each total time in the test was determined. We compared the values obtained in the three conditions, learning, unlearning, and empty (Table 10). Thus, Experiment 2 had a one-factor, three-level (learning, unlearning, and empty), between-subjects design. We also categorized the occurrence of the three categories (face to face, ambiguous, and not paying attention) in the learning-learning pair, as in Experiment 1 (Fig. 2 and Fig. 3).