Perceptual learning of contour integration is not compromised in the elderly

Older adults have decreased ability to extract visual contours from noisy backgrounds. The neural mechanisms underpinning the integration of local features into global shapes are key to human visual object perception. Our study demonstrates that older adults maintain plasticity in these mechanisms. We tested 15 younger (20-34 years) and 17 older (62-78 years) adults on six occasions. The first five sessions were conducted over several weeks, with 3-7 days between visits. The final session was 3 months after the fifth session. Contour processing was measured using closed contours (circles or ellipses) constructed of Gabor elements, embedded in noise (identical Gabors of random orientation). At visits one, five, and six, Glass pattern coherence thresholds were also measured to determine whether learning transferred to an alternate task requiring the extraction of shape signal from noise. Older adults improved in their ability to perform the contour tasks in a similar fashion to younger adults. Improvement was specific to the trained task and performance improvements were maintained over a 3-month period. Our results indicate that plasticity of the aging human visual system is maintained for contour integration.