5.2. Differential olfactory conditioning
In differential olfactory conditioning, a second odorant is introduced into the conditioning protocol, which, however, is unrewarded (Giurfa, 2003). While both odorants are given repeatedly, one of them is always followed by a sucrose reward, while the other odorant is not. This procedure usually produces a stronger conditioned response to the conditioned odorant than simple classical olfactory conditioning. Outside neurobiological studies this assay has, for example, been used successfully to analyse effects of dicifol on learning behaviour of bees (Stone et al., 1997).