Analogy instruction and speech performance under psychological stress.

To examine the efficacy of explicit and implicit forms of instruction for speech motor performance under conditions of psychological stress. In experiment 1, 20 participants were asked to deliver a formal presentation to validate the modified Trier Social Stress Test (TSST). In experiment 2, 40 participants were instructed explicitly by verbal explanation or implicitly by analogy to speak with minimum pitch variation and were subjected to psychological stress using the modified TSST. Acoustic correlates of pitch height (mean fundamental frequency) and pitch variation (standard deviation of fundamental frequency) significantly increased in experiment 1 when participants delivered a speech under modified TSST condition. In experiment 2, explicitly instructed participants were unable to maintain minimum pitch variation under psychological pressure caused by the modified TSST, whereas analogy-instructed participants maintained minimal pitch variation. The findings are consistent with existing evidence that analogy instructions may result in characteristics of implicit motor learning, such as greater stability of performance under pressure. Analogy instructions may therefore benefit speech motor performance and might provide a useful clinical tool for treatment of speech-disordered populations.