title: Anomalous anticipatory skin conductance response to acoustic stimuli: experimental results and speculation about a mechanism.
abstract: OBJECTIVE
  The primary aim of this study was to conduct a replication, simplification, and extension of similar previous studies that claimed anomalous anticipatory skin conductance responses prior to various stimuli and to provide sufficient protocol and analysis details in order to foster additional replications. A secondary aim was to provide a testable model in order to understand the observed results.
  
  
  METHODS
  We used standard skin conductance measures and techniques to search within 50 participants for responses prior to 1-second duration, 97-dB acoustic stimuli, compared to prior to silent controls. We used an interstimulus interval randomly and uniformly distributed between 30 and 50 seconds.
  
  
  METHODS
  The dependent variable was the difference between proportions of 3.5-second prestimulus intervals prior to acoustic stimuli and prior to silent controls that contained a fully formed, nonspecific skin conductance response (ns-SCR). The null hypothesis was that the proportion difference should be zero.
  
  
  RESULTS
  We found a significant proportion difference of 0.032 (Z = 2.08; effect size = 0.077 +/- 0.037; p(1t) = 0.0018), which is a replication of earlier similar studies.
  
  
  CONCLUSIONS
  We examined and ruled out a number of potential artifacts that might have accounted for this finding. To understand these results, we demonstrated, by Monte Carlo techniques, that a possible explanation is that experimenters may have used their own intuition to initiate experiment runs to somehow sort otherwise random nonspecific skin conductance responses into appropriate bins in order to mimic physiological responses. We found experimental evidence to support this idea as an operational mechanism. If this speculation is confirmed in prospective studies, then this intuition-based mimicking of effects may profoundly impact the interpretation of results from complementary and alternative medical studies that use statistical inference to assess outcomes.
authors.affiliation: Laboratories for Fundamental Research, Palo Alto, CA 94306, USA. May@LFR.ORG
authors.forename: Edwin C
authors.initials: EC
authors.lastname: May
authors.forename: Tamás
authors.initials: T
authors.lastname: Paulinyi
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Vassy
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000293:Adolescent; D000328:Adult; D000368:Aged; D001007:Anxiety; D005260:Female; D005712:Galvanic Skin Response / Q000502:physiology; D006801:Humans; D006814:Hungary; D008297:Male; D009010:Monte Carlo Method; D013216:Reflex, Startle / Q000502:physiology; D012107:Research Design / Q000592:standards; D013997:Time Factors