toddler who, if bored in his current situation devoid of arousing stimuli, will walk about until something interesting is found. The observation of curiosity even in the absence of novel stimuli pinpoints one of the major shortcomings in the curiosity-drive model. Optimal-arousal theory Optimal-arousal theory developed out of the need to explain the desire for some to seek out opportunities to engage in exploratory behaviors without the presence of uncertain or ambiguous situations. Optimal-arousal theory attempts to explain this aspect of curiosity by suggesting that one can be motivated to maintain a pleasurable sense of arousal through these exploratory behaviors. The concept of optimal-arousal of curiosity suggests that there is a tendency to maintain an optimal level of arousal. When a stimulus is encountered that is associated with complexity, uncertainty, conflict, or novelty, this will increase arousal, and exploratory behavior is employed to learn about that stimulus and thereby reduce arousal again. In contrast, if the environment is boring and lacks excitement, arousal is reduced and exploratory behavior will be engaged in order to increase information input and stimulation, and thereby increasing arousal again. This theory addresses both curiosity elicited by uncertain or unfamiliar situations and curiosity elicited in the absence of such situations. Cognitive-consistency theory Cognitive-consistency theories assume that "when two or more simultaneously active cognitive structures are logically inconsistent, arousal is increased, which activates processes with the expected consequence of increasing consistency and decreasing arousal." Similar to optimal-arousal theory, cognitive-consistency theory suggests that there is a tendency to maintain arousal at a preferred, or expected, level, but it also explicitly links the amount of arousal to the amount of experienced inconsistency between an expected situation and the actually perceived situation. When this inconsistency is small, exploratory behavior triggered by curiosity is employed to gather information with which expectancy can be updated through learning to match perception, thereby reducing inconsistency. This approach puts curiosity in a broader perspective, also involving aggression and fear. That is, if the inconsistency is larger, fear or aggressive behavior may be employed to alter the perception in order to make it match expectancy, depending on the size of the inconsistency as well as the specific context. Aggressive behavior is assumed to alter perception by forcefully manipulating it into matching the expected situation, while uninhibited fear results in fleeing, thereby removing the inconsistent stimulus from the perceptual field and resolving the inconsistency. Integration of the