The Evolution of Cognitive Search

Search can be defined as an attempt to arrive at a goal at an unknown location in the physical environment, time, memory or any other space. Search is necessary because the quantity and quality of resources essential to survival and reproduction vary in space and time. In addition to exploration through actual body movement in their environment, animals also search their external information space through selective allocation of attention and their internal information space in order to retrieve relevant items from memory. Here we integrate data on search in three distinct domains, physical movement, attention to external information, and locating items in memory, in order to highlight the remarkable similarities among these three domains. First, resources in all three domains are typically distributed in patches. Second, in each of the three domains, animals typically keep searching in patches where they have recently found resources and leave areas where they have either not found or depleted resources. Third, the neurobiological mechanisms modulating the exploration for and exploitation of resources in all three domains involve dopamine and, in many vertebrates, regions of the prefrontal cortex and basal ganglia. We suggest that, throughout evolution, animals co-opted existing strategies and mechanisms used to search their physical space for exploring and exploiting internal and external information spaces. The cross disciplinary integration of theory and data about search can help us guide future research on the mechanisms underlying cognitive search.