Impairment of visual perception in Aging: Compensatory brain mechanisms

Abstract

We have studied the effects of normal aging on visual perception and the existence of possible compensatory brain mechanisms. Were measured in three groups of 30 people with normal vision and average age of 19.6, 42.6 and 65.7 years, the response time to the presentation of stimuli (0.5º in diameter grey circles) sequentially in 24 positions of the visual field, distributed in 8 polar coordinates and 3 eccentricities (2.15, 3.83 and 5.53 degrees of visual field). The stimulus was presented for 100 milliseconds, with low and high contrast (6% and 78%, respectively). The experiments were conducted with and without covert attention to stimuli. With age was observed a progressive increase in the response times from the stimuli of 6% of contrast and those presented in the eccentricity of 5.53º. With covert attention, response times were significantly reduced in the three age groups. However, while the younger and older showed similar reductions in the response times, the adult group obtained minor cuts. These results show that during aging occurs a selective and progressive deterioration in the perception of low contrast and that this deterioration is greater in the peripheral macular areas and that from sixty years the visual attention compensating mechanisms have greater efficiency in the improvement of visual perception.