Motor Learning Effects of Two Types of Stressors: Implications for Practice Specificity

Abstract

Various types of stress have been found to have both positive and negative effects on motor performance (Szalma & Hancock, 2011; Van Gemmert & Van Galen, 1997). One potential explanation for these diverse findings is that stress increases the amount of neuromotor noise in the system (Van Gemmert, 1997). Low levels of stress may have an activating effect on the system which may improve motor performance whereas larger levels of stress decrease motor performance. Research has also suggested that increases in stress increase effort (Hockey, 1997) which may in turn facilitate motor learning (Lee, Swinnen, & Serrien, 1994). The primary purpose of this dissertation was to examine potential effects of cognitive and physical stress on motor learning. Chapter 1 provides some background information on stress and it also introduces some theories developed to explain the relationship between stress and human motor performance. Chapter 2 describes a study on the potential effects of cognitive stress on motor learning. It was found that additional cognitive stress hindered motor performance (p < .001) but did not impede motor learning of a timed aiming task when the cognitive stressor was removed (p > .05). The second experiment (chapter 3) is about the effects of physical stress (80dBs of continuous white noise) on motor learning. Results revealed that increased physical noise negatively affected reaction time (p < .05) on a timed aiming task but did not affect other performance measures (p > .05). During a no stress transfer test the group that practiced with the increased physical stress had marginally longer reaction times (p = .06). In chapter 4 a study about specificity of practice and stress (cognitive and physical) is presented. In this chapter stress was added during a transfer test to see if learning was specific to the environment (stress or no stress) during practice. The addition of cognitive stress during transfer significantly diminished motor performance (p < .001), but the addition of physical stress seemed not to affect motor performance (p > .05). Chapter 5 provides discussion on the results from the three experiments. The results are discussed in the context of practice specificity and the neuromotor noise theory.