In 1885, Hermann Ebbinghaus hypothesised the forgetting curve – the decrease in the ability of the brain to retain memory over time. He created a graph which suggests that although you retain 100% of new information in your short-term memory immediately, within two days, retention drops by 60%. Without re-learning the information at hand, the brain can only keep 10% one week after initial retention. Dr Art Kohn, a professor at Portland State business school goes one step further, stating 50% of information is forgotten after one hour, 70% in 24 hours and 90% in a week.