Posthypnotic suggestion and the modulation of Stroop interference under cycloplegia Amir Raz, a,b, * Kim S. Landzberg, c Heather R. Schweizer, a Zohar R. Zephrani, a Theodore Shapiro, d Jin Fan, d and Michael I. Posner d a Department of Psychiatry, Weill Medical College of Cornell University, White Plains, NY 10605, USA b Department of Psychiatry, Division of Child and Adolescent Psychiatry, Columbia University, College of Physicians and Surgeons and New York State Psychiatric Institute, New York, NY 10032, USA c Department of Ophthalmology, Albert Einstein College of Medicine, Bronx, NY 10467, USA d Department of Psychiatry, Weill Medical College of Cornell University, New York, NY 10021, USA Received 21 October 2002 Abstract Recent data indicate that under a specific posthypnotic suggestion to circumvent reading, highly sug- gestible subjects successfully eliminated the Stroop interference effect. The present study examined whether an optical explanation (e.g., visual blurring or looking away) could account for this finding. Using cy- clopentolate hydrochloride eye drops to pharmacologically prevent visual accommodation in all subjects, behavioral Stroop data were collected from six highly hypnotizables and six less suggestibles using an optical setup that guaranteed either sharply focused or blurred vision. The highly suggestibles performed the Stroop task when naturally vigilant, under posthypnotic suggestion not to read, and while visually blurred; the less suggestibles ran naturally vigilant, while looking away, and while visually blurred. Al- though visual accommodation was precluded for all subjects, posthypnotic suggestion effectively eliminated Stroop interference and was comparable to looking away in controls. These data strengthen the view that Stroopinterferenceisneitherrobustnorinevitableandsupportthehypothesisthatposthypnoticsuggestion may exert a top-down influence on neural processing. Ó 2003 Elsevier Science (USA). All rights reserved. Consciousness and Cognition 12 (2003) 332–346 www.elsevier.com/locate/concog Consciousness and Cognition * Corresponding author. Fax: 1-914-997-8664. E-mail address: amr2006@med.cornell.edu (A. Raz). 1053-8100/$ - see front matter Ó 2003 Elsevier Science (USA). All rights reserved. doi:10.1016/S1053-8100(03)00024-2