Response properties of four example neurons during the sample phase.

<p>A) Left panel: spike-density functions (SDFs) calculated during the sample phase, shown separately for each stimulus (color coded). Bold lines denote S+ and S–, respectively, gray shaded background highlights the duration of the sample phase. Middle panel: behavioral (psychometric, red) and neurometric (blue) generalization gradients. Error bars represent standard error of the mean (SEM), vertical dotted lines identify S+ and S–. Right panel: SDFs triggered relative to individual key pecks, split up according to which stimulus was present during key pecking (color-coded). B,C,D) As in A, but for three different neurons. For the neurons shown in B and C, there were too few spikes around key pecks split up the PPTH according to which stimulus was present.