In a method and system for evaluating interest of a tested animal, first and second dispensers for dispensing respectively a vital first liquid and a second liquid are provided in a closed space confined by a housing for containing the tested animal. The first dispenser dispenses the first liquid at a first position that is easily accessible to the tested animal. The second dispenser dispenses the second liquid at a second position higher than the first position so as to be less easily accessible to the tested animal. Amounts of the first and second liquids consumed by the tested animal within a predetermined time period are measured. The consumed amounts of the first and second liquids are subsequently compared to evaluate interest of the tested animal.