Senior Honors Projects, 2010-current

Date of Award

Spring 2014

Document Type

Thesis

Degree Name

Bachelor of Science (BS)

Department

Department of Psychology

Advisor(s)

Michael D. Hall

Jeffrey T. Andre

Vivien (Kit Ying) Chan

Abstract

The current investigation sought to address several important issues concerning frequency-based acoustic measures of vocal deception, including 1) to provide a direct comparison of aggregate and local measures, 2) to dissociate effects of deception from stress, and 3) to establish an approach that reduces potential adverse effects of stress. Participants were randomly assigned to conditions of truthful or deceptive intent in which they were recorded while answering a series of questions about their academic records. This was done both with and without the presence of a mild stressor. Acoustic measurements then were obtained from the recordings, including aggregate fundamental frequency (F0), F0 variability (% jitter), and local changes in F0 following the beginning of potentially deceptive content. There was an observed effect of stress on aggregate F0, as well as a corresponding marginal effect for local F0 changes. Additionally, a marginal effect of deception on local F0 changes was obtained. Across all observed effects, measured values decreased under conditions of stress/deception, suggesting attempted control of these parameters by participants. The fact that only local measures indicated deception (with much greater observed effect size relative to corresponding aggregate measures) further suggests that local measures are likely to provide a more reliable means by which to detect deception.

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