Abstract: Day - old chicks were trained with varying concentrations of a taste aversant, methyl anthranilate (MeA) , and tested for retention at different time - points after training. Chicks trained with 5% and 20%MeA preserved memory about 15 minutes and 50 minutes respectively , fitting the STM and ITM of the multiple - stage model of memory formation, while those trained with 40%MeA yielded high retention level up to 8 - 10 hours, this time -course appeared to correspond with the glycoprotein - synthesis - independent stage of the LTM. Only MeA over 60% resulted in good reten- tion lasting at least 24 hours. The results demonstrated that the weak - learning. paradigm not only could dissociate the traditional three main stages of memory forma- tion (STM, ITM, LTM), but also could differentiate the LTM into an early and a later phase. This could open a new approach to the further investigations of the mechanisms of memory formation

Key words: day - old chick, memory stage, intensity of training stimulus