Biological Psychology 60 (2002) 51 – 68 Differential conditioning of anticipatory pupillary dilation responses in humans Gu ¨ nter Reinhard *, Harald Lachnit * Department of Psychology, Philipps -Uniersita ¨t Marburg, Gutenbergstr. 18, D-35032 Marburg, Germany Received 23 March 2001; accepted 16 January 2002 Abstract The purpose of the present experiments was to demonstrate conditioning of anticipatory pupillary dilation responses in humans as previous efforts to condition pupillary dilation had yielded inconsistent results. In those studies, using an aversive unconditioned stimulus (US) had yielded more promising results than using non-aversive USs. In three experiments we utilized a reaction time task as a non-aversive US and observed reliable differential conditioning of anticipatory pupillary dilation. Differential responding was evident within very few trials and was largest late in the anticipatory interval. Experiment 4 replicated these findings using an aversive US (electric shock). In measuring anticipatory responses in a differential conditioning preparation all four experiments provided clear evidence for Pavlo- vian conditioning of pupillary dilation in humans. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Pavlovian conditioning; Pupillary response; Humans www.elsevier.com/locate/biopsycho 1. Introduction The purpose of the present experiments was to demonstrate differential Pavlovian conditioning of pupillary dilation responses in humans in order to broaden our arsenal of methods for the examination of the processing of compound stimuli. Previous studies of human Pavlovian conditioning that utilized autonomic re- * Corresponding author. Tel.: +49-6421-2823438; fax: +49-6421-2826621. E-mail addresses: reinharg@mailer.uni-marburg.de (G. Reinhard); lachnit@mailer.uni-marburg.de (H. Lachnit). 0301-0511/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved. PII:S0301-0511(02)00011-X