Brain training puzzles really can boost intelligence, a study shows for the first time. While previous studies have suggested that number puzzles can improve memory and crosswords can expand vocabulary, scientists (51)............... now proved that mental exercise really does (52).............. us more quick-witted. A Swiss-American team reports in a leading scientific journal how computer-based mental exercises were used (53)................ improve overall problem-solving ability.
(54)................ team gave 35 volunteers a series of mental exercises designed to improve their memory. A control group of 35 subjects did not take these tests. Members of the first group were shown a different type (55)................. square every three seconds and asked if a certain square matched (56)................ shown earlier. Participants also heard a series of spoken letters and had to decide (57)................ each was the same as one presented two or three steps earlier in the sequence. If they did well, the task became harder and if they did badly, (58)................ became easier. They repeated the same exercises for between eight and nineteen days. Their problem-solving ability was then compared with the group who (59)................ not done the exercises.
The results of the studies, published in The Proceedings of the national Academy of Sciences, showed that the group who took part in the brain training exercises had a significantly better problem-solving ability than the other group. Moreover, the more participants trained, the more problems (60)................. could solve