Adaptation to leftward-shifting prisms enhances local processing in healthy individuals

• Published in: Neuropsychologia Vol. 56; pp. 418 - 427
• Main Authors: Reed, Scott A., Dassonville, Paul
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.04.2014; Elsevier
• Subjects: Adaptation, Physiological - physiology; Adolescent; Adult and adolescent clinical studies; Attention - physiology; Biological and medical sciences; Disorders of higher nervous function. Focal brain diseases. Central vestibular syndrome and deafness. Brain stem syndromes; Female; Functional Laterality - physiology; Fundamental and applied biological sciences. Psychology; Global processing; Hemispatial neglect; Humans; Illusions; Local processing; Male; Medical sciences; Nervous system (semeiology, syndromes); Neurology; Organic mental disorders. Neuropsychology; Perception; Photic Stimulation; Prism adaptation; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Psychomotor Performance - physiology; Psychopathology. Psychiatry; Vision; Visual Fields - physiology; Visual Perception - physiology; Young Adult; Prism adaptation; Global processing; Illusions; Hemispatial neglect; Local processing; Human; Perceptual adaptation; Nervous system diseases; Healthy subject; Spatial neglect; Perceptual illusion; Cognition; Experimental study; Cerebral disorder; Vision; Central nervous system disease; Global local processing; Perception; Neurological disorder
• ISSN: 0028-3932; 1873-3514; 1873-3514
• DOI: 10.1016/j.neuropsychologia.2014.02.012

In healthy individuals, adaptation to left-shifting prisms has been shown to simulate the symptoms of hemispatial neglect, including a reduction in global processing that approximates the local bias observed in neglect patients. The current study tested whether leftward prism adaptation can more specifically enhance local processing abilities. In three experiments, the impact of local and global processing was assessed through tasks that measure susceptibility to illusions that are known to be driven by local or global contextual effects. Susceptibility to the rod-and-frame illusion – an illusion disproportionately driven by both local and global effects depending on frame size – was measured before and after adaptation to left- and right-shifting prisms. A significant increase in rod-and-frame susceptibility was found for the left-shifting prism group, suggesting that adaptation caused an increase in local processing effects. The results of a second experiment confirmed that leftward prism adaptation enhances local processing, as assessed with susceptibility to the simultaneous-tilt illusion. A final experiment employed a more specific measure of the global effect typically associated with the rod-and-frame illusion, and found that although the global effect was somewhat diminished after leftward prism adaptation, the trend failed to reach significance (p=.078). Rightward prism adaptation had no significant effects on performance in any of the experiments. Combined, these findings indicate that leftward prism adaptation in healthy individuals can simulate the local processing bias of neglect patients primarily through an increased sensitivity to local visual cues, and confirm that prism adaptation not only modulates lateral shifts of attention, but also prompts shifts from one level of processing to another. [Display omitted] . •Assessed local and global processing after prism adaptation in healthy individuals.•Leftward adaptation enhances the local effects that drive illusion susceptibility.•Leftward adaptation has only a marginal effect on susceptibility to global cues.•Adaptation-related enhancement of local processing simulates local bias of neglect.