Why does it seems in similar cases sometimes classic conditioning happens and in others habituation? I'm slightly confused and was hoping you guys could correct me. 

In classic conditioning as with Pavlov's dogs if we ring a bell just before a dog is given food, the bell will give the same response for the dog as the food alone would have, such as an excess of saliva. On a cellular level when two cells fire at a similar time one can cause the other cell to fire.

What I don't understand is why this doesn't happen in cases of habituation. So we already have the connection fattening foods taste good and when we eat a burger it should strengthen the connection between this is a fattening food, you like fattening foods you like this burger, but this doesn't happen if we had burgers everyday we get bored of it.

So guys where am I going wrong here? One a cellular level whats going on?
The Wikipedia article on Habituation explains it fairly well:


  The habituation process is a form of adaptive behavior (or neuroplasticity) that is classified as nonassociative learning. Nonassociative learning is a change in a response to a stimulus that does not involve associating the presented stimulus with another stimulus or event such as reward or punishment.[4] (Examples of associative learning include classical conditioning and operant conditioning). Habituation is the decrease of a response to a repeated eliciting stimulus that is not due to sensory adaption or motor fatigue.


Classical Conditioning strengthens associations and elicits a response because the stimulus is associated with something. The bell means food, pay attention to it. Habituation happens when there's no association; why keep getting worked up by the church bells ringing when you know it doesn't mean anything important (as opposed to a tornado siren).

To generalize "classical conditioning" further into just "associative learning", they're two sides of the same coin; if something is important, connections in your mind strengthen; you remember and a response is illicited. If something isn't important, you stop caring about it and might fail to notice the stimulus at all. This is why excessive fire drills (and worse, false alarms) can be a bad thing; many college students end up being habituated against fire alarms rather than being classically conditioned to know "loud noise" -> "get the heck out".