Conceptual Flexibility: Behavioral And Neural Variations In Semantic Memory Retrieval

Understanding the neural organization of semantic memory- our shared general knowledge- has the potential to uncover the neural mechanisms by which we give meaning to the endless array of objects that we encounter in the world. One prominent set of theories posits a distributed organization of semantic memory-remembering object features activates brain regions overlapping with or adjacent to regions involved in perceiving and acting on those features (e.g., Allport, 1985). Despite accumulated evidence favoring these theories, it is important to understand both the commonalities in the mapping between perception and memory, as well as meaningful variability across sources such as contexts, people, and use. In three studies, we found evidence that while conceptual knowledge is grounded in neural substrates, several factors contribute to variations in semantic memory retrieval. In Chapter 2, we used the logic often used in neuroimaging studies of semantic memory by demonstrating overlapping chromaticity effects (e.g., greater response to colored than grayscale stimuli) in the left lingual gyrus for both color perception and color knowledge. Chapter 3 investigated whether the mapping between perception and memory varied across contexts and participants. Whereas context (here, fidelity of color information as manipulated through task demand) varied the extent to which the left fusiform gyrus was active during a color similarity judgment, individual differences i