The oddball paradigm is an experimental design used within psychology research. Presentations of sequences of repetitive stimuli are infrequently interrupted by a deviant stimulus. The reaction of the participant to this "oddball" stimulus is recorded. Use in ERP research The oddball method was first used in event-related potential (ERP) research by Nancy Squires, Kenneth Squires and Steven Hillyard at the UC San Diego. In ERP research it has been found that an event-related potential across the parieto-central area of the skull that usually occurs around 300 ms after stimuli presentation called P300 is larger after the target stimulus. The P300 wave only occurs if the subject is actively engaged in the task of detecting the targets. Its amplitude varies with the improbability of the targets. Its latency varies with the difficulty of discriminating the target stimulus from the standard stimuli. Detection of these targets reliably evokes transient activity in prefrontal cortical regions. Measuring hemodynamic brain activity in the prefrontal cortex using functional magnetic resonance imaging (fMRI) revealed that the dorsolateral prefrontal cortex is associated with dynamic changes in the mapping of stimuli to responses (e.g. response strategies), independently of any changes in behavior. Since P300 has been shown to be an attention-dependent cognitive component in wakefulness, one might suppose that it would be absent during sleep; a time in which information processing of external stimuli is commonly thought to be inhibited. Research to date indicates that P300 can be recorded during the transition to sleep and then reappears in REM sleep. Stimuli that are rare and intrusive are more likely to elicit the classic parietal P300 in REM sleep. There is, however, little or no positivity at frontal sites. This is consistent with brain imaging studies that show frontal deactivation is characteristic of REM sleep. These findings indicate that while sleepers may be able to detect stimulus deviance in stage 1 and REM, the frontal contribution to consciousness may be lost. Studies of cognition often use an oddball paradigm to study effects of stimulus novelty and significance on information processing. However, an oddball tends to be perceptually more novel than the standard, repeated stimulus as well as more relevant to the ongoing task, making it difficult to disentangle effects due to perceptual novelty and stimulus significance. Evaluating different brain ERPs can decipher this effect. A frontro-central N2 component of ERP is primarily affected by perceptual novelty, whereas only the centro-parietal