{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:13:15Z","timestamp":1760058795086,"version":"build-2065373602"},"reference-count":45,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2025,5,1]],"date-time":"2025-05-01T00:00:00Z","timestamp":1746057600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Medicina"],"abstract":"<jats:p>Background and Objectives: The Oppel\u2013Kundt (O\u2013K) geometric optical illusion has been studied among people with mental disorders to understand the differences in their visual perception. Earlier studies were mainly focused on patients with schizophrenia, while less is known about patients with depression and the influence of medication use. The objectives were to compare illusion manifestation for schizophrenia, depression, and to evaluate possible differences depending on drug use. Materials and Methods: The stimuli consisted of three horizontally arranged dots, which were considered as terminators specifying the ends of the reference and the test stimulus intervals. The reference interval was filled with a set of distracting dots and changed, at random, from 0 to 19. The participants were asked to place the central terminator in the middle, between the outer ones. The trial consisted of 10 different figures, and each trial was repeated 10 times. This study involved 35 patients with depression and schizophrenia spectrum disorders and a comparison group of 35 persons. Information about drug use by patients was retrieved from their medical records. Results: OK illusion manifested stronger in patients with depression compared to the other subjects. The patients who were taking benzodiazepines made greater errors evaluating OK figures than those who were not. No differences were found regarding other drug use. The limitations include a limited sample and possible interfering effects of other drugs, especially antidepressants, which have been shown to affect illusion perception. Conclusions: The OK illusion was more prominent in the patients with depression and in those who were taking benzodiazepines.<\/jats:p>","DOI":"10.3390\/medicina61050835","type":"journal-article","created":{"date-parts":[[2025,5,4]],"date-time":"2025-05-04T20:42:37Z","timestamp":1746391357000},"page":"835","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Variations in Oppel\u2013Kundt Illusion Strength Among Depressive and Schizophrenia Spectrum Disorder Groups: Impact of Benzodiazepine Use"],"prefix":"10.3390","volume":"61","author":[{"given":"Edgaras","family":"Dir\u017eius","sequence":"first","affiliation":[{"name":"Institute of Biological Systems and Genetic Research, Lithuanian University of Health Sciences, LT-44307 Kaunas, Lithuania"},{"name":"Department of Psychiatry, Lithuanian University of Health Sciences, LT-44307 Kaunas, Lithuania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Rasa","family":"Pakanavi\u010di\u016bt\u0117","sequence":"additional","affiliation":[{"name":"Department of Psychiatry, Lithuanian University of Health Sciences, LT-44307 Kaunas, Lithuania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Deimant\u0117","family":"Andriu\u0161kevi\u010di\u016bt\u0117","sequence":"additional","affiliation":[{"name":"Department of Psychiatry, Lithuanian University of Health Sciences, LT-44307 Kaunas, Lithuania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7187-7577","authenticated-orcid":false,"given":"Darius","family":"Leskauskas","sequence":"additional","affiliation":[{"name":"Department of Psychiatry, Lithuanian University of Health Sciences, LT-44307 Kaunas, Lithuania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1149-3296","authenticated-orcid":false,"given":"Aleksandr","family":"Bulatov","sequence":"additional","affiliation":[{"name":"Institute of Biological Systems and Genetic Research, Lithuanian University of Health Sciences, LT-44307 Kaunas, Lithuania"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,5,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"118","DOI":"10.1002\/andp.18631960909","article-title":"Untersuchungen \u00dcber Augenwass Und Optische T\u00e4uschungee. (Researches on Ocular Size and Optic Illusions)","volume":"120","author":"Kundt","year":"1863","journal-title":"Ann. Der Phys."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"443","DOI":"10.55782\/ane-2014-2007","article-title":"Temporal Dynamics of the Oppel-Kundt Illusion Compared to the M\u00fcller-Lyer Illusion","volume":"74","author":"Bertulis","year":"2014","journal-title":"Acta Neurobiol. Exp."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"157","DOI":"10.21307\/ane-2017-048","article-title":"An Effect of Continuous Contextual Filling in the Filled-Space Illusion","volume":"77","author":"Bulatov","year":"2017","journal-title":"Acta Neurobiol. Exp."},{"key":"ref_4","unstructured":"Bulatov, A., Marma, V., Bulatova, N., and Mickien\u0117, L. (2020, August 26). The Filled-Space Illusion Induced by a Single-Dot Distractor, Available online: https:\/\/pubmed.ncbi.nlm.nih.gov\/31038484\/."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"139","DOI":"10.21307\/ane-2020-014","article-title":"Dependence of the Filled-Space Illusion on the Size and Location of Contextual Distractors","volume":"80","author":"Marma","year":"2020","journal-title":"Acta Neurobiol. Exp."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"871","DOI":"10.3390\/medicina45110112","article-title":"Three-Part Oppel-Kundt Illusory Figure","volume":"45","author":"Bertulis","year":"2009","journal-title":"Medicina"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1867","DOI":"10.1016\/j.neuropsychologia.2013.06.013","article-title":"The Two Sides of Spatial Representation in Neglect Patients: The Same Spatial Distortion for Different Patterns of Performance","volume":"51","author":"Manfredini","year":"2013","journal-title":"Neuropsychologia"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"690","DOI":"10.1093\/schbul\/sbr052","article-title":"Perceptual Organization Impairment in Schizophrenia and Associated Brain Mechanisms: Review of Research from 2005 to 2010","volume":"37","author":"Silverstein","year":"2011","journal-title":"Schizophr. Bull."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1016\/j.visres.2014.06.009","article-title":"The Tilt Illusion: Phenomenology and Functional Implications","volume":"104","author":"Clifford","year":"2014","journal-title":"Vis. Res."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"91","DOI":"10.1515\/REVNEURO.2008.19.2-3.91","article-title":"The M\u00fcller-Lyer Illusion as a Tool for Schizophrenia Screening","volume":"19","author":"Pessoa","year":"2008","journal-title":"Rev. Neurosci."},{"key":"ref_11","first-page":"43","article-title":"M\u00fcller-Lyer Illusion Manifestation Peculiarities among People with Schizophrenia and Bipolar Disorders: A Pilot Study","volume":"15","author":"Leskauskas","year":"2013","journal-title":"Biol. Psychiatry Psychopharmacol."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"734","DOI":"10.3758\/s13423-016-1168-5","article-title":"A Review of Abnormalities in the Perception of Visual Illusions in Schizophrenia","volume":"24","author":"King","year":"2017","journal-title":"Psychon. Bull. Rev."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"145","DOI":"10.1080\/13546805.2017.1287693","article-title":"Enlarged Temporal Integration Window in Schizophrenia Indicated by the Double-Flash Illusion","volume":"22","author":"Sinke","year":"2017","journal-title":"Cogn. Neuropsychiatry"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"46","DOI":"10.1016\/j.scog.2015.03.004","article-title":"Schizophrenia and the Eye","volume":"2","author":"Silverstein","year":"2015","journal-title":"Schizophr. Res. Cogn."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"83","DOI":"10.1016\/j.jpsychores.2013.03.008","article-title":"Visual Contrast Sensitivity in Major Depressive Disorder","volume":"75","author":"Fam","year":"2013","journal-title":"J. Psychosom. Res."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"377","DOI":"10.1080\/15622970701513756","article-title":"Vision in Depressive Disorder","volume":"10","author":"Bubl","year":"2009","journal-title":"World J. Biol. Psychiatry"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"2297","DOI":"10.1016\/S0042-6989(01)00104-3","article-title":"Different Effects of Lorazepam and Diazepam on Perceptual Integration","volume":"41","author":"Beckers","year":"2001","journal-title":"Vis. Res."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"379","DOI":"10.1007\/BF00179195","article-title":"Modification of Visual Orientation Illusions by Drugs Which Influence Dopamine and GABA Neurones: Differential Effects on Simultaneous and Successive Illusions","volume":"90","author":"Gelbtuch","year":"1986","journal-title":"Psychopharmacology"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"105","DOI":"10.1007\/BF02246061","article-title":"Effects of Lorazepam on Perceptual Integration of Visual Forms in Healthy Volunteers","volume":"119","author":"Giersch","year":"1995","journal-title":"Psychopharmacology"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1386","DOI":"10.1038\/sj.npp.1300429","article-title":"Lorazepam Strongly Prolongs Visuals Information Processing","volume":"29","author":"Giersch","year":"2004","journal-title":"Neuropsychopharmacology"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"379","DOI":"10.1007\/BF02246113","article-title":"Effects of Lorazepam on Human Contrast Sensitivity","volume":"117","author":"Harris","year":"1995","journal-title":"Psychopharmacology"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"183","DOI":"10.1002\/hup.927","article-title":"Effects of Lorazepam on Visual Perceptual Abilities","volume":"23","author":"Manzano","year":"2008","journal-title":"Hum. Psychopharmacol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"326","DOI":"10.1007\/s002130050678","article-title":"Lorazepam but Not Diazepam Impairs Identification of Pictures on the Basis of Specific Contour Fragments","volume":"138","author":"Wagemans","year":"1998","journal-title":"Psychopharmacology"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"775","DOI":"10.2466\/pms.1974.39.2.775","article-title":"The Oppel-Kundt and the M\u00fcller-Lyer Illusions among Schizophrenics","volume":"39","author":"Letourneau","year":"1974","journal-title":"Percept. Mot. Ski."},{"key":"ref_25","first-page":"259","article-title":"La Perception Des Illusions de Mueller-Lyer et D\u2019Oppel-Kundt Chez Les Deficients Mentaux","volume":"17","author":"Gaudreau","year":"1963","journal-title":"Can. J. Psychol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"101839","DOI":"10.1016\/j.jbtep.2023.101839","article-title":"Visual Illusions in Young People Reporting Psychotic-like Experiences","volume":"79","author":"Sperandio","year":"2023","journal-title":"J. Behav. Ther. Exp. Psychiatry"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"799","DOI":"10.2466\/pr0.1962.10.3.799","article-title":"The Brief Psychiatric Rating Scale","volume":"10","author":"Overall","year":"1962","journal-title":"Psychol. Rep."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"466","DOI":"10.3758\/BF03210936","article-title":"Differentiation and Decrement in the Mueller-Lyer Illusion","volume":"12","author":"Coren","year":"1972","journal-title":"Percept. Psychophys."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"27","DOI":"10.1037\/h0073071","article-title":"Practice and Its Effects on the Perception of Illusions","volume":"9","author":"Judd","year":"1902","journal-title":"Psychol. Rev."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"384","DOI":"10.1007\/s00426-005-0229-6","article-title":"Decrement of the M\u00fcller-Lyer and Poggendorff Illusions: The Effects of Inspection and Practice","volume":"70","author":"Predebon","year":"2005","journal-title":"Psychol. Res."},{"key":"ref_31","unstructured":"The Ashton Manual, and Ashton, H (2002). , Ed., Routledge."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"663","DOI":"10.4088\/JCP.v64n0607","article-title":"Chlorpromazine equivalent doses for the newer atypical antipsychotics","volume":"64","author":"Woods","year":"2003","journal-title":"J. Clin. Psychiatry"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"151","DOI":"10.1192\/bjp.bp.111.100560","article-title":"Effect of Antidepressive Therapy on Retinal Contrast Processing in Depressive Disorder","volume":"201","author":"Bubl","year":"2012","journal-title":"Br. J. Psychiatry"},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Friedel, E.B.N., Tebartz van Elst, L., Schmelz, C., Ebert, D., Maier, S., Endres, D., Runge, K., Domschke, K., Bubl, E., and Kornmeier, J. (2021). Replication of Reduced Pattern Electroretinogram Amplitudes in Depression with Improved Recording Parameters. Front. Med., 8.","DOI":"10.3389\/fmed.2021.732222"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"8571","DOI":"10.1167\/iovs.11-8376","article-title":"Retinal Pathway Origins of the Pattern Electroretinogram (PERG)","volume":"52","author":"Luo","year":"2011","journal-title":"Investig. Ophthalmol. Vis. Sci."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"343","DOI":"10.1007\/s00406-014-0573-x","article-title":"Retinal Dysfunction of Contrast Processing in Major Depression Also Apparent in Cortical Activity","volume":"265","author":"Bubl","year":"2015","journal-title":"Eur. Arch. Psychiatry Clin. Neurosci."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"118","DOI":"10.1016\/j.neubiorev.2015.08.004","article-title":"Dorsal Raphe Nucleus Projecting Retinal Ganglion Cells: Why Y Cells?","volume":"57","author":"Pickard","year":"2015","journal-title":"Neurosci. Biobehav. Rev."},{"key":"ref_38","first-page":"317","article-title":"A Review of Impaired Visual Processing and the Daily Visual World in Patients with Schizophrenia","volume":"80","author":"Kogata","year":"2018","journal-title":"Nagoya J. Med. Sci."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"171","DOI":"10.1034\/j.1600-0447.2001.00160.x","article-title":"Visual Binding Abilities in the Initial and Advanced Stages of Schizophrenia","volume":"103","author":"Parnas","year":"2001","journal-title":"Acta Psychiatr. Scand."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1016\/j.schres.2022.12.030","article-title":"Systematic Review of Visual Illusions in Schizophrenia","volume":"252","author":"Costa","year":"2023","journal-title":"Schizophr. Res."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"324","DOI":"10.1037\/0096-1523.5.2.324","article-title":"Levels of Processing in Visual Illusions: The Combination and Interaction of Distortion-Producing Mechanisms","volume":"5","author":"Coren","year":"1979","journal-title":"J. Exp. Psychol. Hum. Percept. Perform."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"560","DOI":"10.3758\/s13414-021-02412-z","article-title":"Quantitative Study of Asymmetry in the Manifestation of the Wings-in and Wings-out Versions of the M\u00fcller-Lyer Illusion","volume":"84","author":"Bulatov","year":"2022","journal-title":"Atten. Percept. Psychophys."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"229","DOI":"10.1007\/s00213-005-0242-x","article-title":"Some Facilitatory Effects of Lorazepam on Dynamic Visual Binding","volume":"184","author":"Elliott","year":"2006","journal-title":"Psychopharmacology"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"145","DOI":"10.1007\/BF02245623","article-title":"An Effect of Triazolam on Visual Attention and Information Processing","volume":"121","author":"Johnson","year":"1995","journal-title":"Psychopharmacology"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"594","DOI":"10.1080\/08039488.2020.1771767","article-title":"Neurocognitive Effects of Atypical Antipsychotics in Patients with First-Episode Schizophrenia","volume":"74","author":"Hou","year":"2020","journal-title":"Nord. J. Psychiatry"}],"container-title":["Medicina"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1648-9144\/61\/5\/835\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T17:25:41Z","timestamp":1760030741000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1648-9144\/61\/5\/835"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,5,1]]},"references-count":45,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2025,5]]}},"alternative-id":["medicina61050835"],"URL":"https:\/\/doi.org\/10.3390\/medicina61050835","relation":{},"ISSN":["1648-9144"],"issn-type":[{"type":"electronic","value":"1648-9144"}],"subject":[],"published":{"date-parts":[[2025,5,1]]}}}