Before, researchers thought learning occurred by classical and operant only. Although, researchers later found there are biological constraints within conditioning. This contradicts the conditioning theory quite hugely and questions the effectiveness of reinforcement in behaviour.  Discovered by research on animals, studies (Shettleworth, 1975) &(Harlow, 1959), found animals have  biological predispositions in some behaviours, disturbing conditioning.   

B.F. Skinner(1938) invented operant conditioning and it is “learning occurs through reinforcements and punishments”.  Expanding upon “law of effects” by Thorndike(1898, 1911), Skinner proposed using reinforcers can shape animals to the behaviour they are being conditioned too. Reinforcers are a stimulus which follow a behaviour and increase probability it will occur. Thus, reinforcement needs a response to occur. Additionally, reinforcement and punishment are key principles, both consist of positive and negative. Positive reinforcement involves a desirable stimulus being added, whereas negative reinforcement is the removal of aversive stimulus. Both reinforcements increase likelihood of the behaviour. Furthermore, punishment, is an undesirable consequence, which reduces likelihood of behaviour. It has negative side effects, for instance the maintenance of undesirable behaviours.  Another concept in the theory is schedules of reinforcement, it is how often a response is reinforced. It affects how quickly or slowly something is learnt and whether extinction occurs or not.

Research by Breland and Breland (1961) supports that there are biological constraints in operant conditioning. They found natural behaviours of gathering or preparing food, overrides the influence of trained behaviour.

Procedure: Random selection of animals, from a sample of 6,000, did different tasks. One task involved a raccoon having the predicted reinforced response of picking up coins and putting it in a 5-inch metal box. Afterwards, it receives food reinforcement. It consisted of two conditions, one with a single coin and the requirement of dropping it in, then attempt with 2 coins later.

Another task involved a chicken, where the reinforced response was to pull rubber loop, releasing capsule to roll down a slide. Once capsule was at rest at the bottom of the slide, the chicken had to peck it towards the observer. If successful, an automatic feeder reinforced the behaviour. However, before adding the loop, the chickens pecked stationary capsules until pecking behaviour was strong enough to push towards observer.

Lastly, the pigs’ observation occurred over several weeks and involved timing how long it took them to put the dollars in the bank and retrieve others. The predicted reinforced response was picking up a dollar and putting it in the bank, then getting another dollar and so on, until the ratio was complete. Being completed neatly and quickly.

Results: The results showed the failure of the conditioning theory as animals did not demonstrate the conditioned behaviours. The racoons, would not let the coin go, rather would rub it against the inside of the container and clutch it for a few seconds. Finally, it gave the coin back and received food reinforcement. Though, with two coins the rubbing behaviour got worse, despite the non-reinforcement.  As for the chickens, they completed it successfully but later the chickens dragged the capsule to the cage and pounded it up and down on the floor of the cage. Additionally, some chickens could not peck the stationary capsules successfully. Lastly, the pig at first would quickly and neatly take the dollar and put in it in the bank. Although, after few weeks the behaviour was slower; on the way back from the bank, it would drop the dollar, root it, then toss it in the air and drop it again and so on. It was not due to low drive, it occurred despite having strength and increased drive. The pig went through the ratio slowly, taking 10 minutes to transport 4 coins in 6 feet.

Discussion: These results developed an aspect of biological constraints, “instinctive drift”. It is when learned behaviour, overtime, drifts towards instinctive behaviour (Breland & Breland, 1961). They found even though preventing the hungry animal from food reinforcement, instinctive drift occurred. Hence, it went against years of research into the principles of learning. Those principles stated, rewarding behaviour with food reinforcement increases strength of behaviour. Whereas eliminate undesired behaviours which resulted in no food reinforcement.

Conclusion: Overall, there is overwhelming evidence of biological constraints in operant conditioning. Therefore, in future research or therapies involving conditioning of any species, the acknowledgement of the evolutionary history and their instinctive patterns is vital. Otherwise conditioning can fail as animals could go back to biologically predisposed behaviours