Humans are not like machines, for there is always human error. While machines can perform without error, humans cannot. This is clearly shown through the results of the lab. Humans, however, have a learning curve which allows them to improve over time, it is still not equal to the machines' accuracy.
I agree that humans are more likely to create error whereas a machine is specifically designed to process a task, however, humans do contain "machine like qualities". Movements that we make can sometimes be machine like, were we have no control over them and they become a part of our daily function. The brain being a mechanism that allows us to function is somewhat similar to a pulley system allowing a machine to run. The difference being that humans are full of emotion and life and a machine has no feelings at all. Emotion and humanity create numerous variables, the ruler experiment is just one way to view that. However, we know when the ruler drops to catch it. Just like a machine would know the same thing. The variables are different, but our body works in a way in which the movement is consistent and machine like. Humans are obviously not machines, but they do have a thought process that can lead to machine like activity.
I agree with you that humans cannot perform without error. This was apparent in both of our experiments. With humans, both accuracy and precision are compromised.
I agree that humans are always susceptible to error, but someone who repeats an action hundreds of times daily (a card dealer for example) develops such efficiency and precision that the act isn't even thought about, it's just done. What would happen if we were to continue the ruler exercise 100 times a day for a month?
Although humans are different than machines, OuttaTime mentions a good point on the role of repetition. After repeating a task such a large number of times, it will become second nature to the human. They will be able to perform the task with such precision that one could think that the results were generated by a machine and not a human.
