Figure 1.

Figure-ground perception in mice. (A) Schematic of the setup for the behavioral experiment, with a feeding box on the right and two touch screens on the left. (B) The mouse had to choose between a stimulus with a circle (the figure) and a homogeneous display without a circle. Reward was given if the animal chose the stimulus with the figure. During stage 1 of the training process, the mice saw circles that were either lighter or darker than the background. During stage 2 we presented a grating stimulus on a homogeneous background and during stage 3 we included grating figures superimposed on a background with the orthogonal orientation. (C) For the tests of generalization, we either varied the size, the position or the phase of the figure. Note that the grating orientation of the figure and background could be either vertical or horizontal so that the local orientation could not be used to solve the task. (D) Accuracy for the familiar (red bar) and new (blue bar) stimuli in the first sessions of stage 2 and stage 3. Error bars indicate SEM. In stage two, the luminance defined circles were replaced by gratings. Each of the seven mice performed 40 familiar and 60 new trials in stage 2. In stage 3, the mice saw figure-ground stimuli with a figure grating on top of a background with the orthogonal grating for the first time. Here each mouse performed 80 familiar and 28 new trials. Example stimuli are shown underneath each bar. (E) Average baseline accuracy for the figure-ground (stage 3) stimuli and accuracy in the generalization tests. Each mouse performed 100 trials for the baseline condition and 60 trials for each of the other conditions. Error bars indicate SEM across 7 animals.