Repetition priming

Repetition priming refers to improvements in a behavioural response when stimuli are repeatedly presented. The improvements can be measured in terms of accuracy or reaction time, and can occur when the repeated stimuli are either identical or similar to previous stimuli. These improvements have been shown to be cumulative, so as the number of repetitions increases the responses get continually faster up to a maximum of around seven repetitions. These improvements are also found when the repeated items are changed slightly in terms of orientation, size and position. The size of the effect is also modulated by the length of time the item is presented for and the length time between the first and subsequent presentations of the repeated items. Repetition priming refers to improvements in a behavioural response when stimuli are repeatedly presented. The improvements can be measured in terms of accuracy or reaction time, and can occur when the repeated stimuli are either identical or similar to previous stimuli. These improvements have been shown to be cumulative, so as the number of repetitions increases the responses get continually faster up to a maximum of around seven repetitions. These improvements are also found when the repeated items are changed slightly in terms of orientation, size and position. The size of the effect is also modulated by the length of time the item is presented for and the length time between the first and subsequent presentations of the repeated items. Repetition priming can occur without a person being aware of either the repeats or the improvements in his/her response, so it is generally thought to involve implicit memory processes that are dissociable from explicit memory processes. This idea has support from findings that amnesic patients with damage to limbic and/or diencephalic structures show measurable repetition priming effects but have deficits on explicit measures of memory. However, some researchers suggest that implicit and explicit memory systems are not in fact separate. Repetition priming has also been associated with attentional processes, stimulus expectation and episodic memory. Research into repetition priming has been used to investigate the nature of mechanisms underlying the behavioural effects of rapid learning. In utilizing measures of repetition suppression, the putative neural correlate of repetition priming, and measuring changes in the neural response associated with changing the presented stimuli, researchers are attempting to index regions and their processing biases along perceptual, conceptual and response dimensions. This area of research is based on multiple measurement methods from single cell recordings to multi-regional measurements using functional magnetic resonance imaging (fMRI), electroencephalography (EEG) and magnetoencephalography (MEG). Transcranial magnetic stimulation (TMS) has also been used to temporarily 'lesion' (inactivate) specific regions and so get an indication of the necessity of those regions in processing specific dimensions of the presented stimuli. Much of this research has been focused on the visual domain, however auditory and olfactory processes have also been investigated.