How similar were the object to other objects? E.g., were you trying to distinguish an object vs nothing, a bicycle vs a fish, a bird vs a squirrel, or two diff

How similar were the object to other objects? E.g., were you trying to distinguish an object vs nothing, a bicycle vs a fish, a bird vs a squirrel, or two different species of songbird at a feeder? How much would the training requirements increase or decrease moving up or down that scale?