How did even northern states limit the freedoms of blacks even as they decried the expansion of slavery?

new evidence is discovered.

oversights and errors are corrected,

new technology is applied to evidence.

in classical conditioning the organism learns to associate new stimuli with natural, biological responses such as salivation or fear. the organism does not learn something new but rather begins to perform in an existing behavior in the presence of a new signal. operant conditioning, on the other hand, is learning that occurs based on the consequences of behavior and can involve the learning of new actions.