Organization of practice / distribution of trials
| The figure (redrawn from Shea and Morgan (1979) and Jarus (1994)) illustrates how two training regimes produced different results in the short and long term. A group who performed blocked practice learned a skill more quickly. However, a group who practice in a random manner retained a higher level of performance after a ten minute break.
| The benefits of random practice are even more striking after ten days. In this figure's right hand side (redrawn from Shea and Morgan (1979) and Jarus (1994)), the paired words specify how the groups trained - and how they were tested. The "blocked-random" group, for example, trained in a blocked manner but was tested in a random manner. The groups' retention differed most when they were tested in a random manner, the manner in which the environment typically "tests" people's motor skills.
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Shea and Morgan's extremely influential study, replicated many times since it appeared, illustrates the effects on learning of "contextual interference." People retain skills better when they train in an environment or task context that prevents their simply repeating a movement pattern. "Interference," like random, ever-changing practice, forces them to engage in more meaningful processing or regeneration of motor skills.
Bernstein (1967) anticipated these findings when he remarked that "...practice, when properly undertaken, does not consist in repeating the means of solution of a motor problem time after time, but is the process of solving this problem again and again by techniques which we changed and perfected from repetition to repetition. ...Practice is a particular type of repetition without repetition."
References:
Bernstein, N. (1967). The coordination and regulation of movements. New York: Pergamon.
Jarus, T. (1994). Motor learning and occupational therapy: The organization of practice. American Journal of Occupational Therapy, 48, 810-816.
Shea, J.B., & Morgan, R.L. (1979). Contextual interference effects on the acquisition, retention, and transfer of a motor skill. Journal of Experimental Psychology: Human Learning and Memory, 5, 183.
Other sources on organization of practice and contextual interference
Del Rey, P., Whitehurst, M., & Wood, J. (1983). Effect of experience and contextual interference on learning and transfer by boys and girls. Perceptual Motor Skills, 56, 581-582.
Farrow, D., & Maschette, W. (1997). The effects of contextual interference on children learning forehand tennis groundstrokes. Journal of Human Movement Studies, 33, 47-67.
Pinto-Zipp, G., & Gentile, A.M. (2002). Practice schedules and motor learning: Children versus adults. Manuscript submitted for publication.