Psychologists have shown that an individual's inability to recognize once-familiar faces and objects may have as much to do with difficulty perceiving their distinct features as it does with the capacity to recall from memory. A new study suggests that memory impairments for people diagnosed with early stage Alzheimer's disease may in part be due to problems with determining the differences between similar objects. The research contributes to growing evidence that a part of the brain once believed to support memory exclusively -- the medial temporal lobe -- also plays a role in object perception.