Concrete symbols (e.g., "sun," "run") can be learned in the context of objects and actions, thereby grounding their meaning in the world. However, it is controversial whether a comparable avenue to semantic learning exists for abstract symbols (e.g., "democracy"). When we simulated the putative brain mechanisms of…

Using both the lesion method and functional imaging (positron emission tomography) in large cohorts of subjects investigated with the same experimental tasks, we tested the following hypotheses: (A) that the retrieval of words which denote concrete entities belonging to distinct conceptual categories depends upon partially segregated regions in…

Hypothesizes that the human brain localizes mental operations which are integrated in the performance of cognitive tasks such as reading. Provides support of this hypothesis from studies in neural imaging, mental imagery, timing, and memory. (RT)

Illustrates how one can discover structure in mental abilities where none was obvious. Reports that two classes of processes are used to form images. Indicates that imagery is carried out by multiple processes, not all of which are implemented equally effectively in the same part of the brain. (RT)