The illustration given below shows the brain structures responsible for emotions.

Another set of studies of emotional states primarily banks on the changes in the autonomic nervous system (ANS) functions. A large number of studies have measured ANS functions such as heart rate, pulse rate, blood pressure, and galvanic skin conductance to infer emotional state of an individual. Such studies are based on the premise that different emotions elicit distinctive patterns of physiological response. In an interesting study Hubert and Jong-Meyer (1991) screened cartoon film and recorded changes in the ANS functions. Cartoons inducing pleasant and amused state elicited very few changes in bodily sensations, temporary decrease in heart rate, and a rapid decrease in skin conductance. On the other hand, suspense film elicited marked changes in bodily sensations, increase in skin conductance and a temporary decrease in heart rate. Changes in heart rate are influenced by the sympathetic as well as the parasympathetic systems. Hence, psychological states determine the heart rate, which is otherwise a physiological process. On the other hand, skin conductance is entirely influenced by the sympathetic system. It reflects primary arousal in human beings.