A microanalysis of autonomic activity during human speech.

The objective of the current study was to untangle the effects of a number of variables likely to affect autonomic activation during human speech. Thirty-one young adults completed four tasks: 1) talking aloud with an experimenter about a personally relevant topic; 2) counting aloud with the experimenter present; 3) counting aloud while alone; and 4) counting subvocally while alone. Cardiovascular activity was monitored with a digitized, real-time microcomputer-based signal-processing system. Measures included systolic and diastolic blood pressures, heart rate, blood volume pulse, T-wave amplitude monitoring of ECG signals, as well as respiration rate and amplitude. Overall, the measures consistently indicated that 1) the motor efforts required for speech production in a truly low-distress situation were associated with a low level of autonomic activation that exceeded baseline levels only on blood volume pulse and respiration amplitude; 2) experimenter presence significantly enhanced the blood volume pulse response but did not affect any other autonomic index; and 3) talking about personally relevant material triggered dramatically larger responses on nearly all autonomic indices. It is concluded that the motor efforts required for speech production are of minor importance in predicting autonomic responses to tasks involving speech. Speech content (i.e., affect related vs. neutral) has, however, significant impact on autonomic activation during speech.