This series of studies investigated the effectiveness of the PETTLEP model across a variety of tasks. In the first two studies, interventions arising from this model were compared to traditional imagery interventions and physical practice. Study 1 compared a six-week intervention of PETTLEP imagery, traditional imagery, physical practice and an intervention combining PETTLEP imagery and physical practice for strength training. Analysis indicated that the PETTLEP combination group, PETTLEP imagery group and physical practice group improved significantly from pre-test to post-test, whereas the traditional imagery group and control group did not. Study 2 compared the effects of PETTLEP imagery, traditional imagery and physical practice interventions on performance of a computer-game. Results showed that the PETTLEP imagery group and physical practice group improved from pre-test to posttest, whereas the traditional imagery group and control group did not. These two studies indicate that PETTLEP imagery is more beneficial to performance than traditional imagery, and as effective as physical practice. Study 3 and 4 compared differing amounts of PETTLEP imagery on a netball task (over a four week period) and a strength task (over a twenty-two week period). Results indicated that the larger the amount of imagery completed, the larger the apparent performance effect. However, there were exceptions and this should be investigated further with differing doses of imagery, focussing on frequency and volume of imagery. This series of studies has shown PETTLEP imagery to be effective in improving performance on a variety of tasks, including cognitive, motor and strength tasks. It has also shown PETTLEP to be effective over a number of timescales, ranging from forty five minutes to twenty two weeks. In the first two studies it was shown to be as effective as physical practice. Therefore, sport psychologists and coaches should follow the guidelines set out in the PETTLEP model to individualise their imagery interventions and increase their functional equivalence. Additionally, the amount of imagery completed and its ratio to physical practice should also be considered in order to have the greatest possible effect on sports performance. Supplied by The British Library - 'The world's knowledge'