This study tested the relative effects of indulgence and discipline during early rearing (development) in 4 breeds of dogs. The idea originated from the work of D. Levy, who proposed that overindulgence during childhood tended to produce psychopathy in adulthood.

Puppies from 8 litters, 2 each of basenji (African hunting dog), beagle, wire hair terrier, and sheltie (shetland sheep dog), were weaned at 3 weeks and were randomly assigned to two rearing conditions: indulged and disciplined. They lived in pairs in isolation boxes from 3 to 8 weeks of age, and were treated identically except for 2 daily 15-minute treatment periods.

The puppies in the indulged condition were encouraged in any actions they chose and were never disciplined during the experimental treatment periods. The 4 breeds reacted quite differently: basenjis ignored the experimenter and explored; shelties were strongly attracted to the experimenter; beagle and terrier puppies were also attracted to the experimenter.

The puppies in the disciplined condition were trained to sit, stay, follow on a leash during the experimental treatment periods. Again the 4 breeds reacted differently. The basenjis were hard to train, because they wandered away, and affection alone was not a sufficient reward. Shelties were strongly affected by the discipline; they learned easily and became very quiet. Beagles had difficulty learning to stay because they were strongly attracted to the experimenter.

At 8 weeks each dog was tested individually on a new discipline task once a day for 8 days. The dog was put in a room with the experimenter and a dish of meat and was punished each time it came to the dish to eat the meat. After 3 minutes the experimenter left and observed the dog through a one-way mirror for 10 minutes, timing how long the dog stayed away from the meat. The 4 graphs below (data in them are only approximately correct) present the mean number of minutes before the indulged and disciplined dogs of each breed started eating over the 8 days of testing.

Figure 1. Delay in eating meat, after having been punished for eating it. The the indulged and disciplined dogs of the four breeds differ in the way they react. For example the indulged Basenjis delay eating the meat on the first three trials, but by the fourth, they eat as quickly as the disciplined basenjis. In contrast, indulged beagles start out eating the meat promptly but end up not eating the meat at all in the 10-minute test period. The disciplined beagles show the opposite pattern. They delaying eating the meat on the first trials, but they eat promptly on the last. These and other differences in these four graphs are examples of interaction between genetics (dog breed) and environment (indulged vs. disciplined).

The graphs show that:

1. the breeds reacted differently on this test (e.g., basenjis ate promptly; shelties didn't eat;)
2. the effect of the indulged vs. disciplined treatment depended on the breed (e.g., by the end of testing the basenjis and shelties showed no effects of the treatment, whereas the beagles and terriers shows a strong effect: the indulged dogs didn't eat, but the disciplined dogs ate promptly)
3. the same treatment could have quite different effects, depending on the breed (e.g., at the beginning of testing the basenjis and beagles showed opposite effects of the treatment: disciplined beagles and indulged basenjis delayed eating, but indulged beagles and disciplined basenjis ate promptly on trial 1)

Points 2 and 3 are important because they demonstrate the interaction of heredity and environment: the effects of environmental conditions depend on the genetic or hereditary background on which they act -- and vice versa.

Treatment was resumed for four weeks, and the test was repeated with the same results. The dogs were then kept in pens under normal conditions and were observed and tested periodically for a year. These later tests also showed effects of breed, of treatment condition, and their interaction:

Indulged shelties were active, they dominated their quiet disciplined littermates, even though the latter were larger.

Terriers were initially attracted to a visitor. The indulged terriers maintained interest; the disciplined ones lost interest. Disciplined terriers remembered the sit and stay tasks they had learned at 3 -- 8 weeks of age, but they did not come to experimenter when called. Indulged terriers had difficulty staying away from experimenter.

Disciplined beagles acted like normal beagles, strongly attracted to people. Indulged beagles got shyer and shyer; by 10 months they were either completely submissive or ran away from people. It took longer to catch indulged beagles than any other dog. Note the opposite effects of indulgence and discipline on beagles vs. shelties and terriers.

The film's conclusions:

1. Breeds differ in immediate reaction to discipline and indulgence;
2. Breeds differ on later testing depending on rearing conditions;
3. Behavioral differences persisted into adulthood;
4. Behavioral effects of the treatment could appear belatedly in adulthood