dealing with illumination in visual scenes effects of ageing and alzheimers disease处理照明在视觉场景老龄化和老年痴呆症的影响.pdfVIP

Dealing with Illumination in Visual Scenes: Effects of Ageing and Alzheimer’s Disease 1 1 1{ 2 3 1 Gillian Porter *, Ute Leonards , Tom Troscianko , Judy Haworth , Antony Bayer , Andrea Tales 1 Department of Experimental Psychology, University of Bristol, Bristol, United Kingdom, 2 South Glos Memory Service, Avon and Wiltshire Mental Health Partnership, Bristol, United Kingdom, 3 Department of Geriatric Medicine, Cardiff University, Cardiff, United Kingdom Abstract Various visual functions decline in ageing and even more so in patients with Alzheimer’s disease (AD). Here we investigated whether the complex visual processes involved in ignoring illumination-related variability (specifically, cast shadows) in visual scenes may also be compromised. Participants searched for a discrepant target among items which appeared as posts with shadows cast by light-from-above when upright, but as angled objects when inverted. As in earlier reports, young participants gave slower responses with upright than inverted displays when the shadow-like part was dark but not white (control condition). This is consistent with visual processing mechanisms making shadows difficult to perceive, presumably to assist object recognition under varied illumination. Contrary to predictions, this interaction of ‘‘shadow’’ colour with item orientation was maintained in healthy older and AD groups. Thus, the processing mechanisms which assist complex light- independent object identification appear to be robust to the effects of both ageing and AD. Importantly, this means that the complexity of a function does not necessarily determine its vulnerability to age- or AD-related decline. We also report slower re