title: Eye movements of patients with schizophrenia in a natural environment.
abstract: Alterations of eye movements in schizophrenia patients have been widely described for laboratory settings. For example, gain during smooth tracking is reduced, and fixation patterns differ between patients and healthy controls. The question remains, whether such results are related to the specifics of the experimental environment, or whether they transfer to natural settings. Twenty ICD-10 diagnosed schizophrenia patients and 20 healthy age-matched controls participated in the study, each performing four different oculomotor tasks corresponding to natural everyday behavior in an indoor environment: (I) fixating stationary targets, (II) sitting in a hallway with free gaze, (III) walking down the hallway, and (IV) visually tracking a target on the floor while walking straight-ahead. In all conditions, eye movements were continuously recorded binocularly by a mobile lightweight eye tracker (EyeSeeCam). When patients looked at predefined targets, they showed more fixations with reduced durations than controls. The opposite was true when participants were sitting in a hallway with free gaze. During visual tracking, patients showed a significantly greater root-mean-square error (representing the mean deviation from optimal) of retinal target velocity. Different from previous results on smooth-pursuit eye movements obtained in laboratory settings, no such difference was found for velocity gain. Taken together, we have identified significant differences in fundamental oculomotor parameters between schizophrenia patients and healthy controls during natural behavior in a real environment. Moreover, our data provide evidence that in natural settings, patients overcome some impairments, which might be present only in laboratory studies, by as of now unknown compensatory mechanisms or strategies.
authors.affiliation: Department of Neurophysics, Philipps-University Marburg, Karl-von-Frisch-Straße 8a, 35043, Marburg, Germany. stefan.dowiasch@physik.uni-marburg.de.
authors.forename: Stefan
authors.initials: S
authors.lastname: Dowiasch
authors.affiliation: Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Rudolf-Bultmann-Straße 8, 35039, Marburg, Germany.
authors.forename: Bianca
authors.initials: B
authors.lastname: Backasch
authors.affiliation: Department of Neurophysics, Philipps-University Marburg, Karl-von-Frisch-Straße 8a, 35043, Marburg, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Einhäuser
authors.affiliation: Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Rudolf-Bultmann-Straße 8, 35039, Marburg, Germany.|AWO Centre of Psychiatry Halle, Clinic for Psychiatry and Psychotherapy, Zscherbener Str. 11, 06124, Halle, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Leube
authors.affiliation: Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Rudolf-Bultmann-Straße 8, 35039, Marburg, Germany.
authors.forename: Tilo
authors.initials: T
authors.lastname: Kircher
authors.affiliation: Department of Neurophysics, Philipps-University Marburg, Karl-von-Frisch-Straße 8a, 35043, Marburg, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Bremmer
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D004777:Environment; D005133:Eye Movements; D005260:Female; D006801:Humans; D008297:Male; D015835:Ocular Motility Disorders / Q000175:diagnosis / Q000209:etiology*; D010775:Photic Stimulation; D011597:Psychomotor Performance; D012559:Schizophrenia / Q000150:complications*; D014796:Visual Perception; D055815:Young Adult
keywords: Eye movements; Natural environment; Real-world gaze; Schizophrenia; Self-motion