another example of the importance of habituation in the animal world is provided by a study with harbor seals. in one study researchers measured the responses of harbor seals to underwater calls of different types of killer whales. the seals showed a strong response when they heard the calls of mammal-eating killer whales. however, they did not respond strongly when hearing familiar calls of the local fish-eating population. the seals, therefore, are capable of habituating to the calls of harmless predators, in this case harmless killer whales. while some researchers prefer to simply describe the adaptive value of observable habituated behavior, others find it useful to infer psychological processes from the observed behavior change. for example, habituation of aggressive responses in male bullfrogs has been explained as "an attentional or learning process that allows animals to form enduring mental representations of the physical properties of a repeated stimulus and to shift their focus of attention away from sources of irrelevant or unimportant stimulation".