Stable implicit motor processes despite aerobic locomotor fatigue.

Implicit processes almost certainly preceded explicit processes in our evolutionary history, so they are likely to be more resistant to disruption according to the principles of evolutionary biology [Reber, A. S. (1992). The cognitive unconscious: An evolutionary perspective. Consciousness and Cognition, 1, 93-133.]. Previous work (e.g., [Masters, R. S. W. (1992). Knowledge, (k)nerves and know-how: The role of explicit versus implicit knowledge in the breakdown of a complex motor skill under pressure. British Journal of Psychology, 83, 343-358.]) has shown that implicitly learned motor skills remain stable under psychological pressure and concurrent cognitive demands, and recently [Poolton, J. M., Masters, R. S. W., & Maxwell, J. P. (2007). Passing thoughts on the evolutionary stability of implicit motor behaviour: Performance retention under physiological fatigue. Consciousness and Cognition, 16(2), 456-468.] showed that they also remain stable under conditions of anaerobic fatigue that would have significantly challenged the survival skills of our ancestors. Here we examine the stability of an implicitly learned motor skill under fatigue conditions that primarily tax a different physiological system (the aerobic system), but which have equally strong evolutionary connotations. Participants acquired a throwing task by means of an errorless (implicit) learning method or an errorful (explicit) method. Motor performance in the errorless condition, but not the errorful condition, remained stable following an exhaustive VO2 max. running test. Our findings replicate and extend the work of Poolton et al., providing further support for Reber's evolutionary distinction between implicit and explicit processes.