The scientific study of learning in animals is a very recent growth; it may almost be regarded as beginning with Thorndike’s _Animal Intelligence_, which was published in 1911. Thorndike invented the method which has been adopted by practically all subsequent American investigators. In this method an animal is separated from food, which he can see or smell, by an obstacle which he may overcome by chance. A cat, say, is put in a cage having a door with a handle which he may by chance push open with his nose. At first the cat makes entirely random movements, until he gets his result by a mere fluke. On the second occasion, in the same cage, he still makes some random movements, but not so many as on the first occasion. On the third occasion he does still better, and before long he makes no useless movements. Nowadays it has become customary to employ rats instead of cats, and to put them in a model of the Hampton Court maze rather than in a cage. They take all sorts of wrong turnings at first, but after a time they learn to run straight out without making any mistake. Dr. Watson gives averages for nineteen rats, each of which was put into the maze repeatedly, with food outside where the rat could smell it. In all the experiments care was taken to make sure that the animal was very hungry. Dr. Watson says: “The first trial required on the average over seventeen minutes. During this time the rat was running around the maze, into blind alleys, running back to the starting point, starting for the food again, biting at the wires around him, scratching himself, smelling this spot and that on the floor. Finally he got to the food. He was allowed only a bite. Again he was put back into the maze. The taste of the food made him almost frantic in his activity. He dashed about more rapidly. The average time for the group on the second trial is only a little over seven minutes; on the fourth trial not quite three minutes; from this point to the twenty-third trial the improvement is very gradual.” On the thirtieth trial the time required, on the average, was about thirty seconds.[3] This set of experiments may be taken as typical of the whole group of studies to which it belongs. [3] Watson, _Behaviorism_, pp. 169–70. Thorndike, as a result of experiments with cages and mazes, formulated two “provisional laws,” which are as follows: “The Law of Effect is that: of several responses made to the same situation, those which are accompanied or closely followed by satisfaction to the animal will, other things being equal, be more firmly connected with the situation, so that, when it recurs, they will be more likely to recur; those which are accompanied or closely followed by dissatisfaction to the animal will, other things being equal, have their connections with that situation weakened, so that, when it recurs, they will be less likely to recur. The greater the satisfaction or discomfort, the greater the strengthening or weakening of the bond.