[Towards a deterioration of the structural and perceptive representations of objects in physiological aging?]

Previous data collected in healthy elderly participants by our laboratory suggested impairment of visual and auditory object processing in normal aging. This impairment seemed not to be related to simple perceptual deficits. The aim of the present study was to identify the mechanism of this disorder according to serial models of object recognition, by dissociating the recognition abilities using naming tasks from a visual and from auditory stimuli, perceptual representations (visual and auditory), and semantic knowledge on the same 62 objects. Fifty three healthy participants were divided in three groups according to age (20-30 years, n = 17; 40-50 years, n = 14; 60-95 years, n = 22). They performed a battery assessing visual and auditory naming, judgement on semantic knowledge and perceptual visual properties, and matching of perceptual auditory properties of the same objects. The aged participants had lower performance on the naming tasks in both modalities, and worse perceptual properties performances again for both modalities than the other two groups. However, no significantly statistical difference was found on the semantic task. A significant correlation was found between age and the scores on each of the four tasks on which aged participants had lower scores than the youngest ones. No statistical difference was found between the two younger groups, but a trend was shown for the perceptual properties. Thus a degradation of perceptual representations of objects seems to be present in normal aging, but the nature of this degradation has to be specified.