cue, the participant tries to recall the exemplar (e.g. Food-C__, Food-S__, Red-T__, Red-Bl__). Anderson and Spellman observed that items that shared a semantic relationship with practiced information was less recallable. Using the example from above, recall of items related to practiced information, including tomato and strawberry was lower than recall for cracker, even though strawberry is part of a different pair. This finding suggests that associative competition by explicit category cue is not the only factor in retrieval difficulty. They theorized that the brain suppresses, or inhibits, non-practiced attributes. This explains why an item that is very similar to tomato, but not from the same pair, also exhibits decreased recall rate. "Think/no-think" paradigm and intentional inhibition During the recovered memory debate of the 1990s, cognitive psychologists were dubious about whether specific memories could be repressed. One stumbling block was that repression had not been demonstrated in a research study. In 2001, researchers Anderson and Green claimed to have found laboratory evidence of suppression. They trained their participants with a list of unrelated word pairs (such as ordeal-roach), so they could respond with the second member of the pair (roach) when they saw the other member (ordeal). The more frequently participants had tried to not think about a particular word, the less likely they were to retrieve it on a final memory test. This impairment even occurred when participants were given an "independent probe" test, i.e. given a similar category (insect) instead of the original cue (roach), and asked to fill in the blank on the memory test: insect-r_. According to Anderson and Green, the fact that participants had a decreased ability to recall items they were told to forget strongly supports the existence of an inhibitory control mechanism and the idea that people have the ability to suppress unwanted memories. Though Anderson & Green's (2001) results have been replicated several times, a group of prominent psychology researchers using the same methodology as the original study were unable to replicate even the basic result (Bulevich, Roediger, Balota, & Butler, 2006). They determined that suppression is not a robust experimental phenomenon in the think/no-think paradigm and suggested that Anderson and Green's findings could be explained by retroactive interference, or simply thinking about X when told to "not think" about Y. Amnesia for trauma or abuse Amnesia, the forgetting of important personal information, usually occurs because of disease or injury to the brain,