The results show that most participants can consistently make accurate grammatical/non-grammatical assessments of the new sentences, even though few can correctly articulate the rules that they are using to make those assessments. AGL is used in many studies as a measure of implicit learning or memory along with a separate test for explicit learning or memory in response to a certain variable. One study investigated the relationship between age and learning style, i.e. explicit versus implicit. An AGL task was used because of its ability to measure both implicit and explicit learning. One group of participants was given strings made from a complex grammar, with no mention in the instructions about the underlying rules. This was thought to increase the amount of implicit learning, as more complex rules are harder to perceive and participants were not attempting to find them. Another group was given strings made from a simple grammar, with instructions to try to figure out the rules. This was thought to increase the amount of explicit learning, as participants were consciously attempting to find rules that were easy to perceive. The results showed that aged adults performed poorly on the task that emphasized explicit learning compared to young adults; however, both groups performed similarly on the task that emphasized implicit learning. This demonstrates that the aging effects seen with explicit memory do not have an effect on implicit memory. A 2002 study was done investigating the neural correlates of AGL. Data from amnesic patients with medial temporal damage whose performance on AGL tasks is no different from controls show that this area is not implicated with AGL. The learning phase was conducted as usual for the participants, and the test phase was conducted with the participants inside an fMRI scanner. The results showed a greater activity in the left superior occipital cortex and right fusiform gyrus for grammatical stimuli, and greater activity in the left angular gyrus during grammaticality judgments, as compared to a matched recognition control task. Reber's original AGL theory is rule-based; participants learn and apply the formal rules of the artificial grammar through viewing grammatical strings. However, there are many alternate theories to describe the knowledge that is obtained through learning an artificial grammar. This theory states that participants do not acquire the abstract rules exactly as stated by the artificial grammar. Instead, participants develop their own rules based on small sections of each letter string. For example, they may notice that an F always comes after an M. The existing AGL paradigm is criticized for having only two responses: grammatical or non-grammatical. In one study, participants were asked to indicate why they felt a certain sentence was grammatical or non-grammatical.