Pavlov's Experiments With Dogs & Their Reflex Behavior

Reflexes occur where nervous pathways transmit impulses from one pathway to another. The well known unconditioned knee-jerk reflex occurs when the incoming sensory nerves from just below the knee cap sense a jolt, which is transmitted to the spinal column, where there is a junction (synapse) with a motor nerve, which is activated, transmitting a message to the extensor thigh muscles, which suddenly constrict, causing the lower leg to jerk forward.

Knee-jerk reflexes are easy to understand, since they do not involve the brain. However, thousands of other reflexes involving the brain are constantly at work. Some of these are activated consciously, others operate unconsciously. Hence, the nervous system is defined in two branches of control; voluntary (under conscious control) and involuntary (controlled unconsciously).

In Ivan Pavlov's experimental work with dogs, he sounded a bell and then gave the dogs a bit of solid food (meat or bread) which produced salivation. This was repeated until the dogs salivated for the bell just as if it were food. He called the food an unconditioned stimulus and the bell a conditioned stimulus, even though solid food for dogs is actually a conditioned stimulus.

Surprisingly, salivating for solid food is not an inborn, unconditioned reflex. In another Russian experiment, puppies were weaned and fed only milk for several months. They did not salivate when they smelled, saw or ate solid food until they had eaten it several times!

So, Pavlov's famous bell-food experiments actually conditioned salivation from one conditioned reflex to another. On the other hand, injecting lemon juice into a dog's mouth and producing salivation, or pricking a leg with a pin and causing a withdrawal movement, were genuinely innate reflexes. Pavlov's work, and the resulting publicity, have helped explain a great deal about both animal and human behavior, some of it to the benefit of dogs in general.

However, there is a down side to Pavlov's publicity: It created the general impression that discoveries about laboratory dogs, in a totally unnatural environment, explain the behavior of wild animals and/or domestic pets living in active, often hectic social environments. The result is that some behaviorists still struggle to diagnose and solve behavior problems using purely conditioned behavioral theory, disregarding principles derived from empirical (practical) experience. Perhaps more unfortunately, Pavlov's work tended to validate some popular concepts that animals can't think, they merely respond to stimuli and behave like robots.