Kornhuber and Deecke's discovery of the Bereitschaftspotential (German for readiness potential) led to research on the now extensively used LRP, which has often been investigated in the context of the mental chronometry paradigm.
Part of this preparation includes a slow negative wave bilaterally distributed over pre- and post-central sites, the readiness potential.
[2] Vaughan, Costa, and Ritter (1968) noted that the readiness potential was larger contralateral to the side of the body where the muscle contraction occurred.
[3] The only RPs that do not seem to be lateralized are face and tongue movements which have symmetrical distribution over both hemispheres with the maximum of the potential located in the lower half of the central sulcus.
That the lateralized aspect of the readiness potential in general might be used to measure the amount of motor preparation for a direct specific action, termed "corrected motor asymmetry", was highlighted by De Jong and Gratton et al.[4] The LRP is elicited whenever a subject initiates a voluntary movement with his/her hand (or feet).
The amplitude of the lateralization effect is thought to represent the amount of differential response preparation elicited by the warning stimulus.
This type of paradigm, called "masked priming", has been used with the LRP to see whether a cue someone is unable to identify at all is still able to influence the response system.
This suggests that a cue with newly learned meaningful implications for the motor system (i.e., arbitrary response-mappings) need not be consciously processed in order for response preparations to begin.
Thus since the LRP can pick up signals for responses never actually initiated or perceived of, it can uncover information processing that happens without our awareness but that can still affect our overt behavior.
In a Go/No-Go paradigm participants are told to respond with their right or left hand according to a specific feature of a presented target.
This paradigm helps answer questions about the order of information extraction by through comparison of LRPs (or lack of) to stimulus features in the Go versus No-Go conditions.
To verify the order of information extraction it is important to flip the features that are mapped to hand selection and the No-Go instruction.
For example, one study used the LRP component to characterize the temporal order with which grammatical and phonological information about a word is retrieved when preparing to speak.
Similarly, another study[9] used the LRP in a Go/No-Go paradigm to show that conceptual information about nouns (e.g., is the depicted item heavier or lighter than 500g?)
[11][12] Together, these studies show how the LRP has helped to map out the temporal dynamics of information processing during speech production.
[13][14] As described above, experiments have used the LRP to generate support for a continuous model of stimulus evaluation and response selection.
This is in contrast to a discrete model that predicts full stimulus evaluation must be complete before response initiation can start.
The research question was whether during the spatial stroop task conflict on position-inconsistent (or, incongruent) trials is represented in the motor response stage as can be indexed by the LRP.
In a follow-up study by the same group Kolev et al., 2006 used the LRP again to show that the effects from their 2004 study generalized to the auditory domain, and to extend further support that the effects of aging on slowed response time in a four choice reaction time task is in the response generation and execution stage and not in stimulus processing and selection.
Generally, the amplitude of the lateralization effect is thought to represent the amount of differential response preparation elicited by the cue or warning stimulus.
In an experiment by Gratton, Coles, Sirevaag, Erikson, and Donchin in 1988,[20] the time of response initiation, defined as the latency of onset of EMG activity, was examined in relation to the LRP.
[21] In their paper on inferences from CNV and LRP they cited experiments done by Ulrich, Moore, & Osman (1993) in which three hypotheses could be derived.
The muscle-specific preparation hypothesis gained the most support with follow up studies (Ulrich, Leuthold, & Sommer, 1998).
They demonstrate that the more the subject knows about the direction and which hand to move, for example, the larger the foreperiod of the LRP even in conditions that stress time and pressure.