Page "Do Androids Dream of Electric Sheep?" Paragraph 7

Earlier androids were easier to detect because of their limited intelligence.

As android technology improved, bounty hunters had to apply an empathy test — the Voigt-Kampff test — to distinguish humans from androids, by measuring empathetic responses, or lack thereof, from questions designed to evoke an emotional response, often including animal subjects and themes.

Because androids are not sympathetic, their responses are either absent or feigned, and measurably slower than a human's.

The simpler Boneli Test, used by another police department in San Francisco, measures the reflex-arc velocity in the spinal column's upper ganglia, by testing their reaction time to visual stimuli.

However, the only way to be sure beyond a shadow of a doubt that an individual is an android is to take a bone marrow sample.