Search

Three experiments explored whether patterns of eye movements during reading might help explain syntactic prominence effects that are typically observed using reaction time tasks. Participants read sentences in which target words were in syntactically prominent or syntactically less prominent positions. Across all three experiments, using three types of syntactic prominence manipulations, there were fewer fixations and shorter reading times for words in more prominent positions, indicating that enhanced accessibility of syntactically prominent words is not caused by increased processing time. Rather, syntactic prominence appears to facilitate early encoding/lexical access and sentence integration processes while also, as shown previously, increasing activation of concepts in a comprehender's sentence or discourse representation. We propose that enhanced encoding and sentence integration processes can be attributed to an increase in attentional resources for more prominent concepts, and that this increase derives from readers' immediate sensitivity to informational prominence contours that are signaled by syntax. doi: 10.3758/MC38.6.740

When two masked, to-be-attended targets are presented within approximately half a second of each other, performance on the second target (T2) suffers, relative to when the targets are presented further apart in time or when the first target (T1) can be ignored. This pattern of results is known as the attentional blink (AB). Typically, participants differ with respect to the magnitude of their AB and their overall target accuracy. Despite investigations as to what participant characteristics may influence AB performance (e.g., age, brain damage, or mood state), there has been no focused examination of whether individual differences in cognitive performance measures predict the magnitude of the AB or overall rapid serial visual presentation (RSVP) target accuracy. Our university student participants performed single-target and dual-target RSVP tasks, as well as a selection of cognitive tasks that did not use RSVP presentations, with color, letter, digit, and object stimuli. Overall performance on each of the RSVP targets (T1, T2, and single target) was predicted by speeded manual and vocal identification times to isolated stimuli and by performance with other RSVP targets. However, the magnitude of the AB was predicted only by T1 accuracy, not by any other performance measures. The results suggest that individual differences in AB magnitude do not result from differences in effective RSVP target encoding and are not well explained by varied information-processing abilities.

Keywords: saccades; smooth tracking; microgravitation Abstract: The effects of prolonged microgravity conditions on the performance of visual tracking functions such as fixational rotations of the eyes (saccades), smooth tracking of linear and curved movements of a foveal point stimulus, and following a vertical pendulum-like movement of foveoretinal optokinetic stimuli were studied. Experiments were performed on 31 cosmonauts in freefall conditions, in ten cases followed by additional studies after a cycle of head movements and in 14 after resting. These experiments showed that while intrinsic visual functions were retained in microgravity conditions, there were decreases in the precision and speed measures of all types of visual tracking (fixational rotations of the eyes, smooth tracking) and, in some cases, complete degradation of the smooth tracking reflex, an increase in the time taken to fix the gaze on a target (by factors of 2 or more), and decreases in the frequency of stimulus tracking. During the initial period of adaptation to the altered gravitational conditions and periodically during prolonged flight, the system of smooth visual tracking was found to undergo a transition to a strategy of saccadic approximation, in which gaze tracks the movement of the target using a set of macro- or microsaccadic movements. These impairments, seen in virtually all the cosmonauts, resulted from vestibular deprivation (functional deafferentation of the otolith input) in conditions of weightlessness, while in cosmonauts conceptualizing space on the basis of perceiving the positions of the feet and head additionally showed support-tactile deprivation. Article History: Registration Date: 07/10/2004

Byline: Alessandro Serra (1), Joy Derwenskus (1), Deborah L. Downey (1), R. John Leigh (1) Keywords: Key words eye movements; saccades; internuclear ophthalmoplegia Abstract: Background and Purpose: Modern neuroimaging has demonstrated progression of disease in multiple sclerosis (MS) that may not be detected by standard clinical protocols, prompting a search for new, sensitive tests. Methods: In fifty patients with MS, we examined eye movements, with particular attention to the speed and accuracy of saccades, and the vestibulo-ocular reflex during small, high-speed head rotations. We also measured the subjective visual vertical (SVV), using a modified laser-pointer. Visual function was measured, and patients were graded using the Kurtzke Functional Neurological Status (FSS), and Expanded Disability Status Scale (EDSS). Results: Our main finding was that patients showing abnormalities of eye movements (20/50) were more disabled than those with a normal examination (EDSS scores significantly different, p &lt 0.01), although the ages and duration of disease were similar in both groups. Saccadic dysmetria and internuclear ophthalmoparesis were common. SVV was abnormally large in 36 % of patients these showed abnormal eye movements and poorer visual acuity more commonly than those with normal SVV. In patients with the largest deviations of SVV, Kurtzke FSS cerebellar functions were significantly worse (p = 0.021). Conclusions: Clinical examination of eye movements, with attention to dynamic properties of saccades and the vestibulo-ocular reflex, takes only a few minutes to perform, but may provide better information concerning the presence of brainstem and cerebellar involvement than Kurtzke protocols. Measurement of SVV is possible in the clinic and is a sensitive sign of brainstem dysfunction our present study suggests that SVV is also affected when cerebellar circuits are involved in MS. Prospective studies are required to determine whether the development of abnormalities with ocular motor and SVV testing are predictive of disease activity and progressive disability in MS. Author Affiliation: (1) Neurology Service, Department of Veterans Affairs Medical Center, &amp University Hospitals, Case Western Reserve University, Cleveland, Ohio, USA, US (2) Institute of Clinical Neurology, University of Sassari, Sassari, Italy, IT (3) Department of Neurology, University Hospitals, 11100 Euclid Avenue, Cleveland, Ohio, 44106--5040, USA. rjl4@po.cwru.edu, US Article note: Received: 9 August 2002, Received in revised form: 20 November 2002, Accepted: 28 November 2002 Correspondence to R. John Leigh, M. D.

Byline: Dianne L. Koczat (1), Sally J. Rogers (1), Bruce F. Pennington (2), Randal G. Ross (1,3) Keywords: Endophenotype; saccade; autism Abstract: Autistic probands exhibit impaired spatial accuracy and impaired response suppression errors during a delayed oculomotor response task. Family members of autistic probands, and thus the possible familial nature of these deficits, have not been assessed. Eleven parents of autistic probands and 17 adults from unaffected families, ages 25--50 years, completed oculomotor delayed-response tasks. Parents of autistic probands demonstrated poorer spatial accuracy than the comparison group (p = .002), with no significant differences between groups on percentage of premature saccades or latency of remembered saccades. Spatial working memory deficits, as measured by the delayed oculomotor response task, appear to be familial in families with an autistic proband. These deficits deserve further evaluation as a potential endophenotypic marker for genetic risk for autism. Author Affiliation: (1) Department of Psychiatry, University of Colorado Health Sciences Center, Denver, Colorado (2) Department of Psychology, University of Denver, Denver, Colorado (3) Department of Psychiatry, Denver Veterans Administration Medical Center, Denver, Colorado Article History: Registration Date: 12/10/2004

Ontological changes in the composition of damselfish eye lenses are discussed relative to possible effects on trace-metal accumulation. The eye lenses of Parma microlepsis from rocky barrens of Sydney were found to have concentrations of Sr, Rb, Hg and Ba above quantitative detection limits of solution-based inductively coupled plasma-mass spectrometry. The central nucleus and the softer surrounding cortex were separated, and nuclei had lower concentration of the metals, except for Ba, for which concentration was the same. Differnetial binding affinities for the crytallins may partly account for trace-metal differences seen in the nuclei and cortices.

Byline: C. Kemner (1), M. N. Verbaten (2), J. M. Cuperus (1), G. Camfferman (2), H. van Engeland (1) Keywords: Saccadic eye movement; autism Abstract: The saccadic eye movements, generated during a visual oddball task, of autistic children, normal children, children with attention deficit disorder and hyperactivity (ADDH), and dyslexic children were examined to determine whether autistic children differed from these other groups in saccadic frequency. Autistic children made more saccades during the presentation of frequent stimuli (than normals and ADDH children), and between stimulus presentations. Also, unlike the normal and dyslexic groups, their saccadic frequency did not depend on stimulus type. This abnormal pattern of saccades may negatively influence the ability to attend to stimuli, and thereby learning processes. Suggestions are made with respect to possible abnormalities in subcortical mechanisms involved in saccade generation. Author Affiliation: (1) Department of Child and Adolescent Psychiatry, Utrecht University, Utrecht, The Netherlands (2) Department of Psychoparmacology, Utrecht University, Utrecht, The Netherlands Article History: Registration Date: 29/09/2004

Byline: M. Doran (1), A. J. Larner (1) Author Affiliation: (1) Walton Centre for Neurology &amp Neurosurgery, Lower Lane, Liverpool, L9 7LJ, UK Article History: Registration Date: 01/01/2004 Received Date: 23/01/2003 Accepted Date: 07/07/2003

Byline: S. E. Murik (1) Author Affiliation: (1) Irkutsk State University, Irkutsk, Russia Article History: Registration Date: 11/10/2004