Updated based on comments:
In what ways can we distinguish a human being doing certain activities online and a bot programmed to do similar activities, say checking email, downloading some music files, shopping on ebay, searching on Google etc., or maybe trying to deface/hack a website, brute force a log-in password etc.
To limit the scope of the question and make it more clear, let us restrict our observations only to network-oriented behavior, some examples being- the amount of time spent doing XYZ thing online, the amount/type of data downloaded (say) from a file sharing website, the number of friends/followers on Social media websites, etc.
I guess it should possible to obtain some 'patterns' which will distinguish human behavior and programmed behavior.
The Turing test is not what I am looking for.
What techniques can be useful here? Machine learning? Game theory?
References to relevant academic/research articles will also be good.