Variability in the effect of light on recognition memory performance. The left panel shows that, in the implanted mice, in 8 out of the 10 cases there was a light-intensity dependent disruption on performance (red); in the remaining 2 cases there was a light-intensity dependent facilitation (green). Similarly, the right panel shows that, in the non-implanted mice, in 9 out of the 12 cases there was a light-intensity dependent disruption (red); in the remaining 3 cases there was a light-intensity dependent facilitation (green).