Recent research on human-dog interactions showed that talking to and petting a dog are accompanied by lower blood pressure (BP) in the person than human conversation. To clarify whether cognition, conditioning, or tactual contact exerted the major influence in this so-called "pet effect," 60 male and female undergraduates with either positive or neutral attitudes toward dogs interacted with a dog tactually, verbally, and visually while BP and heart rate were recorded automatically. Results revealed that (a) subjects' BP levels were lowest during dog petting, higher while talking to the dog, and highest while talking to the experimenter and (b) subjects' heart rates were lower while talking or touching the dog and higher while both touching and talking to the dog. Touch appeared to be major component of the pet effect, while cognitive factors contributed to a lesser degree. Implications for coping with hypertension are discussed, and suggestions for further research are stated.