Online learning in a familiarity-based recognition memory.

Novel patterns are streamed continuously into the memory and "one-shot" learned. Memory responses to trained patterns are shown as a distribution in light blue; distribution of responses to untrained (random) patterns is shown in light red. Recognition threshold separating the two distributions is shown as a green dashed line, set to produce a 1% false positive error rate. As stored patterns approach the end of their lifetimes, their traces decay and begin to merge with the untrained background distribution, leading to an increase in the false negative error rate (i.e. "misses"). Capacity is operationally defined as the pattern age at which the miss rate (averaged over all patterns up to that age) becomes unacceptably high (chosen to be 1% here).