A while ago I was waiting for the bus at the Canon shopping centre when a couple of seats over a man lit up one of the most foul smelling cigarettes I had ever smelled. Curiously, he was doing so right underneath a “no smoking” sign that was stuck to the wall of the bus shelter.
This is not the first time I’d seen someone blatantly do the exact opposite of what the prohibition sign right above their heads was telling them to do. In my hometown, the train/bus station is a spot where shady people like to get drunk, especially so in the evening (hence their shadiness). Because this makes late night train-goers uncomfortable and because these people often harass other members of the public, signs were put in the middle of the train/bus station. The signs clearly state that drinking is illegal in that square and that anyone caught drinking will be fined about £310.
A £310 fine should be ample incentive to not drink there, yet I’ve seen people throw empty beer cans on a bench underneath one of those signs. Why? Because only those who get caught drinking will have to pay the fine. In terms of learned behaviour, this can be seen as operant conditioning on a variable interval schedule. The £310 fine is a positive punishment for illegal behaviour (Skinner, 1953). That means that if the behaviour the police is trying to decrease (drinking, in this case) presents itself, a punishment will be issued in the form of a £310 fine. The effectiveness of this positive punishment depends on the schedule it follows (Skinner & Ferster, 1957). In this case, the punishment follows the illegal behaviour only if the police are present. That’s not ideal because the presence of the police is irregular and intervals in between when they’re present are irregular too. This means that punishment follows a variable interval schedule (Skinner & Ferster, 1957). A variable interval schedule is one of the least effective types of schedules, because there’s no consistency in punishment and this makes it harder for people to learn the contingency between behaviour and punishment (Skinner, 1953; Skinner & Ferster, 1957).
On top of that, the variable interval schedule allows the possibility for the people who drink in zones where they’re not allowed to learn associations besides the intended “illegal behaviour —> expensive fine” association. For example, they could learn that drinking alcohol where they shouldn’t is only punished when the police are present, but not when they’re absent. That’s called three-term contingency, wherein a discriminant stimulus directly affects the likelihood of the behaviour leading to the punishment (Skinner, 1953).
So -- are prohibition signs effective in keeping people from participating in illegal behaviour? Not for everyone. For people who are particularly afraid of punishment, they will be (Gertz & Gould, 1995). For reward-oriented people they can be quite useless, as these people perceive risks as smaller than they are (Harbeck, Glendon & Hine, 2017). Similar to Harbeck et al.'s findings, the risk of getting caught by the police would be smaller in the eyes of reward sensitive people than in the eyes of punishment sensitive people.
Gertz, M. G., & Gould, L. C. (1995). Fear of punishment and the willingness to engage in criminal behavior: A research note. Journal of Criminal Justice, 23, 377-384. DOI: 10.1016/0047-2352(95)00027-N
Harbeck, E. L., Glendon, A. I., & Hine, T. J. (2017). Reward versus punishment: Reinforcement sensitivity theory, young novice drivers’ perceived risk, and risky driving. Transportation Research Part F: Traffic Psychology and Behaviour, 47, 13-22. DOI: 10.1016/j.trf.2017.04.001
Skinner, B. F. (1953). Science and human behavior, New York, NY, Free Press. Retrieved from: https://books.google.co.uk/books?hl=nl&lr=&id=Pjjknd1HREIC&oi=fnd&pg=PA1&dq=science+and+human+behavior&ots=iQqdAyD0pK&sig=zXhTEF8YY-63SCfGir85eCroY-0#v=onepage&q&f=false
Ferster, C. B., & Skinner, B. F. (1957). Schedules of Reinforcement (1997 ed.), Prentice-Hall, Inc. Retrieved from: https://books.google.be/books?id=xctyCQAAQBAJ&printsec=frontcover&hl=nl&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false