VISUAL AND SEMANTIC DETERMINANTS OF OBJECT RECOGNITION DEFICITS IN EARLY ALZHEIMERS-DISEASE

The visual and semantic factors underlying recognition deficits in Alz heimer's disease were investigated. To control for object form we used triads of computer-generated blobs. Triads either shared visual featu res or were visually distinct. Triads were artificially labeled using semantically close or distinct, biological, or nonbiological names (e. g., lion, tiger, zebra or violin, guitar, banjo vs robin, donkey, frog or kite, wrench, carriage). On test trials blobs were presented alone and patients attempted to recall their ''name.'' Visually close triad s were misidentified significantly more often than visually distinct t riads. Irrespective of whether biological or non-biological labels wer e used, triads labeled with semantically close names were misidentifie d significantly more often than semantically distinct triads. Hence, p roblematic object categories are those whose exemplars are visually an d semantically close.