title: Comparison of video- and EMG-based evaluations of the magnitude of children's emotion-modulated startle response.
abstract: We investigated the reliability and validity of a video-based method of measuring the magnitude of children's emotion-modulated startle response when electromyographic (EMG) measurement is not feasible. Thirty-one children between the ages of 4 and 7 years were videotaped while watching short video clips designed to elicit happiness or fear. Embedded in the audio track of the video clips were acoustic startle probes. A coding system was developed to quantify from the video record the strength of the eye-blink startle response to the probes. EMG measurement of the eye blink was obtained simultaneously. Intercoder reliability for the video coding was high (Cohen's kappa = .90). The average within-subjects probe-by-probe correlation between the EMG- and video-based methods was .84. Group-level correlations between the methods were also strong, and there was some evidence of emotion modulation of the startle response with both the EMG- and the video-derived data. Although the video method cannot be used to assess the latency, probability, or duration of startle blinks, the findings indicate that it can serve as a valid proxy of EMG in the assessment of the magnitude of emotion-modulated startle in studies of children conducted outside of a laboratory setting, where traditional psychophysiological methods are not feasible.
authors.affiliation: Department of Psychiatry, University of Wisconsin, Madison, Wisconsin 53719, USA. mjessex@wisc.edu
authors.forename: Marilyn J
authors.initials: MJ
authors.lastname: Essex
authors.forename: H Hill
authors.initials: HH
authors.lastname: Goldsmith
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Smider
authors.forename: Isa
authors.initials: I
authors.lastname: Dolski
authors.forename: Steven K
authors.initials: SK
authors.lastname: Sutton
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Davidson
mesh_terms: D002648:Child; D002675:Child, Preschool; D004576:Electromyography; D004644:Emotions; D005260:Female; D006801:Humans; D008297:Male; D013216:Reflex, Startle / Q000502:physiology*; D014743:Videotape Recording