The study of learning and memory are divided between pre- and post-Ebbinghaus. His contribution was that significant.
Hermann Ebbinghuas was born in Bonn, Germany during the middle of the nineteenth century, 18 years after Wundt and six years before Freud. He attended the University of Bonn and studied language, history and philosophy. Ebbinghaus was a rationalist and wrote his dissertation on Hartmann’s philosophy of the unconscious. Interestingly, his son became a well-known philosopher (Julius Ebbinghaus).
Ebbinghaus was a gentleman scholar. He inherited enough wealth to spend his time researching whatever interested him. And many things interested him.
Ebbinghaus was the first person to publish an article on measuring the intelligence of school children. When French psychologists Binet and Simon created the first standardized test of intelligence, they include Ebbinghaus’ sentence completion task.
He is also known for the Ebbinghaus illusion. This is a visual image of two same-sized circles surrounded by other circles. The comparison of the large and small surrounding circles makes it appear that the same-sized circles are actually different sizes. It is a demonstration of the impact of context on our perceptual system.
Ebbinghaus’ papers were organized in four parts: introduction, method, results and discussion. His contemporaries adopted this approach and it is now the standard organization for research journals.
But Ebbinghaus is best known for his work on memory and forgetting. He got interested in the subject after reading Fechner’s book on psychophysics. Although memory had been discussed by philosophers and studied after the fact, no one before Ebbinghaus had studied the process of memory as it occurred. Philosophers started with existing associations and inferred backwards; Ebbinghuas studied the entire memory process by learning, forgetting and relearning material.
An extremely thorough investigator, Ebbinghaus varied the size of the lists being memorized, standardized their presentation (one per tick of a clock), and recorded the number of exposures needed to relearn. Keeping the words in order, like a pack of cards, he quickly looked that the word, and went on to the next one. When he reached the end of the list, he paused for 15 seconds, and went through the list again. He stopped only when he had achieved “complete memory” (prefect recall of the list one time). He found that overlearning, continuing on after complete memory was the best way to learn lists.
Ebbinghaus proved some things people already knew but had never shown experimentally. He showed that the more repetitions made, the more items are learned. This practice effect had long been known but never experimentally verified.
Everyone also knew that forgetting increases over time but Ebbinghuas showed that forgetting follows a predictable pattern. If time alone was the sole cause, forgetting would show a steady linear increase. This is what happens with motor skills. Every day you don’t play the piano, you get a little worse. But lists are different. Ebbinghaus showed that forgetting occurs rapidly and then tapers off.
Everyone knew that meaningful material is easier to learn than those with random associations. But according to Ebbinghaus, not only are meaningful words easier to recall, it takes 10 times more exposure to material in order to learn random words.
Everyone knew about the serial position effect but couldn’t prove it. With a long list, we remember the first part of the list best, the last part of the list second best, and the middle of the list the least. Ebbinghaus proved this pattern occurs with long lists of any material. The position on the list influences the difficulty.
First, Ebbinghaus discovered that the difficulty and amount learned are not related one-to-one. Difficult lists often require much more effort than easy ones. It is not a linear relationship. There is a linear relationship between learning and the amount of time spent studying. The more time spent studying, the more learning occurs.
Second, there is a very rapid forgetting of verbal material in the first hour. This is the largest drop in memory. The drop in memory flattens out to about 30% in about two days. Memory levels drop to about 10% within 30 days. A month after learning a list is only slightly worse than 8 hours.
Ebbinghuas’ third discovery is that recall is better if learning is space out over small study sessions. This discovery of distributed practice is why professors say not to cram for tests. You will remember it best if you learn it over time.
Fourth, Ebbinghaus proved that associations within a list aid memory. If you can find items that go together, the list is easier to learn. Nonadjacent associations are helpful but adjacent associates are very helpful.
Fifth, the best strategy for limiting the decline of recall is to overlearn the material. Ebbinghaus studied a list until he could say it correctly once (what he called “complete memory”). But if he continued to study a list beyond that level, there was less forgetting.
Here’s how he did it
Ebbinghaus’ procedure was to use himself as the subject but impose careful controls. The list of was presented on cards, one word per card. They were kept in the same order (which turns out to make list learning easier). He used a watch or metronome) to set the pace one card per sec. When he reached the end of list, Ebbinghaus would pause for 15 seconds. Then he would either do another run through the cards or try to recall the list.
At first, Ebbinghaus used names of sounds. Later, he used random words that had no theme. These were normal words but the list was nonsense. Ebbinghaus then switched to words he created, such as CVC (consonant-vowel-consonant, such as BOK) or CCC (consonant-consonant-consonant, such as BLV) combinations.
On Day 1, he might learn a list of 16 to 20 items, repeating it 8, 16, 24, 32, 42, 53 or 64 times. Then on Day 2, 24 hours later, we would relearn the list to perfection. The main score was the number of trials it took to relearn the list. The better he remembered, the more effort he saved, so he called the difference savings.
Nearly 100 years after Ebbinghaus, memory research Alan Baddeley studied Ebbinghaus’ concept of distributed practice. The British postal service was modernizing its system and needed to teach its employees how to type. Baddeley divided them into groups. One group practiced their typing one hour a day for 5 days a week. Another group practiced two 2-hour sessions for 5 days a week. The 1-hour a day group did best. They learned the quickest (less hours) and retained it better a year after their training.
But when given a choice, people preferred the dual 2-hour per day method. The 1 hour per day training learned faster (55 hours versus 80 hours) but it took more time away from work (11 weeks versus 4 weeks). The postal employees were afraid they’d lose their jobs if they were away from work too long.
The best schedule for maximum effect with the least amount of effort is 1 hour per day. It takes more weeks but less hours to become proficient.