Comparison between psychometric and neurometric performance based on simulated PSTHs derived from neuronal pools of various size (3–160) and composition (i.e., rank ordered response quality, 10–80 best neurons). Best-responding neurons were taken to be the neurons showing the highest number of excess spikes (top: intensity code) or highest vector strengths (bottom: frequency code) for 60 Hz stimulation. Top: Spike count code. Difference of spike-count-based neurometric performance (full stimulus interval) and psychometric performance plotted as Euclidean distance (ED) for all parameter combinations (matrix, most similar is blue, most dissimilar is red). Three examples of resulting neurometric curves (blue) are shown. The psychometric curve is replotted (red) in each graph to ease comparison. The best model found (minimum ED) is highlighted by the gray background. Bottom: Same for time locking. Note that the neurometric variable is based on rhythmicity obtained from population PSTHs and not from measures of vector strength (the latter is not accessible for the brain without prior knowledge about stimulus phase).