Editing Classical conditioning (section)

===Data sources===

Experiments on theoretical issues in conditioning have mostly been done on [[Vertebrate|vertebrates]], especially rats and pigeons. However, conditioning has also been studied in [[Invertebrate|invertebrates]], and very important data on the neural basis of conditioning has come from experiments on the sea slug, ''[[Aplysia]]''.<ref name="Shettleworth_2010" /> Most relevant experiments have used the classical conditioning procedure, although [[Operant conditioning|instrumental (operant) conditioning]] experiments have also been used, and the strength of classical conditioning is often measured through its operant effects, as in ''conditioned suppression'' (see Phenomena section above) and [[Shaping (psychology)|autoshaping]].