Arousal and cognition are distinct but we often experience their interplay in a single instance. If you chance upon a rattle snake in the backyard, you would feel totally alerted and/or scared (physiological arousal), and your past experience with or knowledge of poisonous snakes provides the cognition of the situation. Cognition reminds us of cognitive phenomenon, such as understanding, intending, remembering, and so on. Arousal is an emotional sensation that occurs when we are, say, in a state of alertness. There is accumulated evidence that shows that when we are in a state of alertness, one’s brain activity in terms of electric firings, for example, is greater than we are in a state of calm, and lesser than when we are in a state of anxiety.