Finally, we examined whether mice could retain the capability of visual recognition and VR performance after they were trained. Accordingly, we established a 3-stage training/testing protocol (Fig 5A). During the first stage, a group of mice were trained for 21 days to recognize a downward moving target following the same schedule illustrated in Fig 2A. As shown in Fig 5B, the number of rewards per session increased after this training period, but did not reach a plateau. During the second stage, the mice were held in their home cages without any training and given free food access for 22 days. During the third stage, the mice were reintroduced to VR training for an additional 16 days and then we evaluated their performance. When the mice were reintroduced to training during the third stage, there was no Acclimation, or Target Identification phase (Fig 5A). To determine how well the memory was retained over the three-week break period (the second stage), the number of rewards per session during the first six sessions of the third stage (9.56±2.2) was compared to that of the Acclimation phase (day 1–3.5; 0.03±0.03 rewards/session), Baseline phase (day 6.5–9; 7.43±0.87 rewards/session), the initial Data Acquisition phase (day 19–21.5; 14.36±1.6 rewards/session) of the first stage, and the final six sessions of stage 3 (Final phase, 23.39±2.4 rewards/session). The average number of rewards during the initial six sessions of the third stage (Retrain phase) is statistically higher than that of the Acclimation phase of the first stage (Fisher’s PLSD, P<0.0001), and the average number of rewards during the final six sessions (Final) is significantly higher than any other training phase. However, the average number of rewards during the first six sessions of the third stage (Retrain phase) is not statistically different from that of the Baseline (Fisher’s PLSD, p>0.05) but is statistically different from that of the Data Acquisition phases of the first stage (Fisher’s PLSD, P<0.05) (see S1 Table for detailed results of Fisher’s PLSD tests). Fig 5D shows the cumulative distributions of the frequency of rewards/session of stage 1 and stage 3 of training. It is evident that the mice had a more rapid increase in rewards per session during stage 3, than they did during stage 1. A Kolmogorov-Smirnov (K-S) test confirmed that the difference of the distributions of the rewards/session of these two stages is statistically significant (P<0.001). Therefore, the non-maximum training during stage 1 facilitates the learning during stage 3.