Sniffy. For teaching Operant Conditioning. When given food, if it’s near to it, it goes to it. When does the same actions in the same place and gets food again – or it doesn’t – learns an internal model of how to get food.


  • Model designed to teach operant conditioning – shaping and partial reinforcement – to psychology students. Created mainly for two reasons: financial costs and ethical challenges of using real rats in class.
  • Operant conditioning: train the rat to press the bar for food. In contrary to real rats, which must be deprived of food for 24h before the experiment, Sniffy is always hungry.
  • Primary/secondary reinforcers, shaping, conditioning, extinction behaviors. CRF (Continuous reinforcement), PRF (partial reinforcement).
  • Written in C. Animation was created out of videos of real rats, with about 15 different actions. Actions are played randomly. It is dependent on where the rat is located.
  • Rat has an internal model:
    • Guess_Responses: true if he believes is in a ratio schedule; false for interval schedule.
    • Guess_value: size of schedule.
    • Guess_fixed: it is behaving as if the schedule is fixed.
    • theory_valid: has evidence about the correctness of the schedule model.
    • The position in which he was when received food and the time between going to the position and receiving it.
  • Belief is proportional to reinforcement frequency.
  • In its conclusion, proposes to use Artificial Neural Networks.


  • Actions are random, not constructed based on the behavior of real rats.
  • Parameters of the simulation come with default values but can be overwritten by students. Again, it is interesting to construct better default values based on real rats.
  • Technology advances in the past 25 years make possible to use Artificial Neural Networks more easily.