le importance if the next trial
began instantly (as in unspaced learning), but can have no importance
when so long as interval as a day is left between trials; for
evidently the recency of twenty-four hours plus ten seconds is not
effectively different from that of an even twenty-four hours. Recency,
then, does not explain the law of effect.

Can it be explained as an instance of the sub-law of intensity? An
animal, or man, who sees success coming as he is making the reaction
that leads directly to success, throws himself unreservedly into this
reaction, in contrast with his somewhat hesitant and exploratory
behavior up to that time. The dammed-up energy of the
reaction-tendency finds a complete outlet into the successful
reaction, and therefore the successful reaction is more intensely
exercised than the unsuccessful. This seems like a pretty good
explanation, though perhaps not a complete explanation.

Limitations of the Law of Exercise

The law of exercise, with all its sub-laws, is certainly fundamental
and universal; it is always in operation whenever anything is learned;
and yet, just by itself, it goes only halfway towards accounting for
learned reactions. For a reaction to be exercised, it must be _made_,
and the law of exercise presupposes that it is made, and does not
attempt to account for its being made in the first place.

{394}

The law of exercise does not cover the formation of new linkages, but
only the strengthening of linkages that are already working. It does
not explain the attachment of a response to some other than its
natural stimulus, nor the combination, of responses into a higher
unit, nor the association of two facts so that one later recalls the
other. We learn by doing, but how can we do anything new so as to
start to learn? We learn by observing combinations of facts, but how
in the first place do we combine the facts in our minds?

How, for example, can we learn to respond to the sight of the person
by saying his name? Evidently, by exercising this linkage of stimulus
and response. But how did we ever make a start in responding thus,
since there is nothing about the person's looks to suggest his name?
The name came to us through the ear, and the face by way of the eye;
and if we repeated the name, that was a response to the auditory
stimulus and not to the visual. How has it come about, then, that we
later respond to the visual stimulus by saying the name?

In short, the more s