If a subject's pulse rate is 102 bpm while under the influence of PCP and marijuana, this is an example of which effect?

The scenario presented can be accurately characterized as an additive effect. In this context, both PCP (phencyclidine) and marijuana have individual effects on the body's physiological functions, such as heart rate. When a subject consumes both substances, the overall impact on the pulse rate is the sum of the effects produced by each substance independently. For instance, if PCP raises the pulse rate and marijuana has a mild calming effect on the heart rate, the combined effect could result in a higher overall pulse than what would occur with either drug alone.

An additive effect is simply where the total effect of two drugs is equal to the sum of the individual effects, without any increase or decrease in the effects due to the interaction between the two substances. This phenomenon is essential in understanding how different drugs can compound their effects when used together, exemplified by the increased heart rate in this scenario.