Statistics of FF of (neuron, bin) pairs in each task. Histograms of the change in FF (delay – foreperiod) under the preferred and least-preferred stimulus conditions, for all (neuron, bin) pairs with well-tuned delay activity. Empirical results contradict sharply the theoretical predictions of burst-coding models. A-C, In all three datasets, the change in FF was significantly <0 for both preferred and least-preferred stimulus conditions. *p < 0.05. **p < 0.01. ***p < 0.001.