PubMed · 1997 · 10 citations · 0 references
MedicineNeurosciencePsychiatryCognitive NeuroscienceEye MovementsVisual AttentionAttentional ControlAttentional SelectionEye Movement AnalysisEye-movement ControlNeural Basis Of AttentionSelective AttentionCovert SaccadesSaccade LatencySaccadic Eye Movement ControlSaccadic Eye Movement DisordersSaccadic Eye Movement PhysiologySaccadic Latency MeasurementSustained Attention DeficitTiming Of Saccades
Saccadic latency of schizophrenics (N = 15) and normal controls (N = 11) was measured to the left and right visual fields with three fixation conditions that differentially affect saccade latency. Fixation was offset either 1) prior to the target (gap condition), 2) simultaneous with the target onset (control condition), or 3) after target onset (overlap condition). Saccade latencies are typically reduced in the gap condition, which is attributed to the fixation offset acting to facilitate attentional disengagement or as a preparatory warning signal. Repeated measures Analysis of Variance (ANOVA) revealed that whereas the saccadic latencies of schizophrenics and normal controls do not differ for right visual field targets, the schizophrenics' latencies were prolonged to left visual field targets. This difference was most pronounced in the overlap condition, where normal controls produced faster saccades to the left visual field targets, whereas schizophrenics showed the opposite asymmetry. Because the overlap condition provides no early warning of the upcoming target, the lateralized finding suggests a deficit in the right hemisphere mechanisms responsible for sustained attention.