Average responses strength to each call type for three example units with low, medium, and high selectivity. The title of each bar plot shows the value of the Z-based selectivity index (SI) for the corresponding example unit. TheZscored response strength (Z) of all auditory units in the entire dataset (n = 292) is shown on the color matrix. Each row of this matrix shows the average Z obtained in a unit for each call type of the zebra finch repertoire. The call types on the x axis have been sorted according to the average Z for that call type across all units: distress calls (Di) had the highest average response strength followed by song (So), etc. Units on the y axis are first sorted according to the call type that gave the highest Z for that unit following the order of the x axis: 51 units had the peak responses for distress call, 61 for song, etc. Within each of these blocks, the rows were further sorted according to the Z-based SI: the most selective units are on the bottom of the block and the least selective at the top.
