Spaced study also fixes the matter more durably. Every student knows that continuous "cramming" just before an [{343}] examination, while it may accomplish its immediate purpose, accomplishes little for permanent knowledge.
When we say that spaced repetitions give best results in memorizing, that does not mean that study generally should be in short periods with intervals of rest; it says nothing one way or the other on that question. The probability is, since most students take a certain time to get well "warmed up" to study, that fairly long periods of consecutive study would yield larger returns than the same amount of time divided into many short periods. What we have been saying here is simply that repetition of the same material fixes it better in memory, when an interval (not necessarily an empty interval) elapses between the repetitions.
Whole versus part learning.
In memorizing a long lesson, is it more economical to divide it into parts, and study each part by itself till mastered, or to keep the lesson entire and always go through the whole thing? Most of us would probably guess that study part by part would be better, but experimental results have usually been in favor of study of the whole.
If you had to memorize 240 lines of a poem, you would certainly be inclined to learn a part at a time; but notice the following experiment. A young man took two passages of this length, both from the same poem, and studied one by the whole method, the other by the part method, in sittings of about thirty-five minutes each day. His results appear in the table.
LEARNING PASSAGES OF 240 LINES, BY WHOLE AND PART METHODS
(Pyle and Snyder)
Method of study Number Total number
of days of minutes
required required
30 lines memorized per day,
then whole reviewed till it
could be recited 12 431
3 readings of whole per day
till it could be recited 10 348
Here there was an economy of eighty-three minutes, or nearly twenty per cent., by using the whole method as against the part method. Similar experiments have regularly given the same general result.
However, the matter is not quite so simple, as, under certain conditions, the results tend the other way. Let us consider a very different type of learning test. A "pencil maze", consisting of passages or grooves to be traced out with a pencil, while the whole thing was concealed from the subject by a screen, was so arranged that it could be divided into four parts and each part learned separately. Four squads of learners were used. Squads A and B learned the maze as a whole, squads C and D part by part. Squads A and C learned by spaced trials, two trials per day. Squad B learned the whole thing at one sitting; while squad D, which came off best of all, learned one part a day for four days, and on the fifth day learned to put the parts together. The results appear in the adjoining table, which shows the average time required to master the maze by each of the four methods.
PART AND WHOLE LEARNING, SPACED AND UNSPACED,
IN THE PENCIL MAZE (From Pechstein)
Spaced trials Unspaced trials
Whole learning A 641 seconds B 1250 seconds
Part learning C 1220 seconds D 538 seconds