Lynch, J. J., McCarthy, J. F. 1969. Social responding in dogs: heart rate changes to a person. Psychophysiology 5(4), 389-393.

This paper reports the variable conditional effects of a person on the heart rate of nine mongrel dogs. There were three experimental procedures: person present and playing a passive role, person present and playing an active role (petting the dog), and person present and serving as a signal for forthcoming electrical stimulation. The order of presentation of these conditions was counterbalanced with dogs assigned randomly to one of three orders of procedures. Each procedure consisted of 50 trials (exposures to a human). On each trial, the person entered the conditioning room and stood motionless for 40 sec. The petting and shock reinforcements occurred 40 sec after the person entered the room, enabling the study of conditional heart rate changes in the interval from appearance of the person to reinforcement. Heart rate changes varied with the meaning of the person, and the rates from high to low were in the order: person serving as a signal for subsequent punishment, person alone, and person serving as a signal for subsequent petting. It was stressed that an experimenter could have marked and varied social-psychophysiological effects upon the individuals being studied, and that in any experiment it is necessary to properly evaluate these effects.