FIG. 3.

Use of a threshold parameter θ as a constraint on the summed output of all HLNs (a) and the maximum HLN output value (b) to reject data from “novel” species (not present in the training data). The proportion of test data patterns failing to satisfy the constraint, and therefore rejected as unknown, is shown for the 20 trained species (○) and the 14 novel species (▴).