higher levels of Extraversion were associated with faster responses. Although the authors note this is likely a function of specific task demands rather than underlying individual differences, other authors have proposed the RT-Extraversion relationship as representing individual differences in motor response, which may be mediated by dopamine. However, these studies are difficult to interpret in light of their small samples and have yet to be replicated. In a similar vein, other researchers have found a small (r < 0.20) association between RT and Neuroticism, wherein more neurotic individuals tended to be slower at RT tasks. The authors interpret this as reflecting a higher arousal threshold in response to stimuli of varying intensity, speculating that higher Neuroticism individuals may have relatively "weak" nervous systems. In a somewhat larger study of 242 college undergraduates, Neuroticism was found to be more substantially correlated (r ≈ 0.25) with response variability, with higher Neuroticism associated with greater RT standard deviations. The authors speculate that Neuroticism may confer greater variance in reaction time through the interference of "mental noise." See also CDR computerized assessment system Implicit-association test Inspection time Jensen box Movement in learning Psychomotor agitation Psychomotor learning Psychomotor retardation Timed antagonistic response alethiometer References Further reading External links Reaction Time Test – Measuring Mental Chronometry on the Web Historical Introduction to Cognitive Psychology Timing the Brain: Mental Chronometry as a Tool in Neuroscience Cognition Time in life