for as much as 50% of the variance seen in memory tasks. Proteins identified in animal studies have been linked directly to a molecular cascade of reactions leading to memory formation, and a sizable number of these proteins are encoded by genes that are expressed in humans as well. In fact, variations within these genes appear to be associated with memory capacity and have been identified in recent human genetic studies. Complementary Processes The idea that the brain is separated into two complementary processing networks (task positive and task negative) has recently become an area of increasing interest. The task positive network deals with externally oriented processing whereas the task negative network deals with internally oriented processing. Research indicates that these networks are not exclusive and some tasks overlap in their activation. A study done in 2009 shows encoding success and novelty detection activity within the task-positive network have significant overlap and have thus been concluded to reflect common association of externally oriented processing. It also demonstrates how encoding failure and retrieval success share significant overlap within the task negative network indicating common association of internally oriented processing. Finally, a low level of overlap between encoding success and retrieval success activity and between encoding failure and novelty detection activity respectively indicate opposing modes or processing. In sum task positive and task negative networks can have common associations during the performance of different tasks. Depth of Processing Different levels of processing influence how well information is remembered. This idea was first introduced by Craik and Lockhart (1972). They claimed that the level of processing information was dependent upon the depth at which the information was being processed; mainly, shallow processing and deep processing. According to Craik and Lockhart, the encoding of sensory information would be considered shallow processing, as it is highly automatic and requires very little focus. Deeper level processing requires more attention being given to the stimulus and engages more cognitive systems to encode the information. An exception to deep processing is if the individual has been exposed to the stimulus frequently and it has become common in the individual’s life, such as the person’s name. These levels of processing can be illustrated by maintenance and elaborate rehearsal. Maintenance and Elaborative Rehearsal Maintenance rehearsal is a shallow form of processing information which involves focusing on an object without thought to its meaning or its association with other objects. For