page_title: Response priming
section_title: Rapid-chase theory
hierarchical_section_title: Response priming / Theories / Rapid-chase theory
caption_attribution_description: English: Rapid chase theory in response priming
context_page_description: In the psychology of perception and motor control, the term response priming denotes a special form of priming. Generally, priming effects take place whenever a response to a target stimulus is influenced by a prime stimulus presented at an earlier time. The distinctive feature of response priming is that prime and target are presented in quick succession and are coupled to identical or alternative motor responses. When a speeded motor response is performed to classify the target stimulus, a prime immediately preceding the target can thus induce response conflicts when assigned to a different response as the target. These response conflicts have observable effects on motor behavior, leading to priming effects, e.g., in response times and error rates. A special property of response priming is its independence from visual awareness of the prime.
context_section_description: The rapid-chase theory of response priming was proposed in 2006 by Thomas Schmidt, Silja Niehaus, and Annabel Nagel. It ties the direct parameter specification model to findings that newly occurring visual stimuli elicit a wave of neuronal activation in the visuomotor system, which spreads rapidly from visual to motor areas of the cortex. Because the wavefront of activity spreads very fast, Victor Lamme and Pieter Roelfsema from the University of Amsterdam have proposed that this wave starts as a pure feedforward process (feedforward sweep): A cell first reached by the wavefront has to pass on its activity before being able to integrate feedback from other cells. Lamme and Roelfsema assume that this kind of feedforward processing is not sufficient to generate visual awareness of the stimulus: For this, neuronal feedback and recurrent processing loops are required that link widespread neuronal networks.
  According to rapid-chase theory, both primes and targets elicit feedforward sweeps that traverse the visuomotor system in rapid succession until they reach motor areas of the brain. There, motor processes are elicited automatically and without the need for a conscious representation. Because the prime signal has a head-start over the target signal, primes and targets are engaged in a "rapid chase" through the visuomotor system. Because the prime signal reaches the motor cortex first, it is able to activate the motor response assigned to it. The shorter the prime-target SOA, the quicker the target can start the pursuit. When the target signal finally arrives at the motor cortex, it can continue the response process elicited by the prime (if prime and target are consistent) or redirect the response process (if prime and target are inconsistent). This explains why response priming effects increase with prime-target SOA: the longer the SOA, the more time for the prime signal to control the response on its own, and the further the response activation process can proceed in the direction of the prime. Under some circumstances, the prime can also provoke a response error (leading to the characteristic priming effects in error rates). Such a time-course of sequential motor control by primes and targets was described in 2003 by Dirk Vorberg and coworkers in a mathematical model and fits the time-course of primed motor potentials in the EEG.
  According to rapid-chase theory, response priming effects are independent of visual awareness because they are carried by rapid feedforward processes whereas the emergence of a conscious representation of the stimuli is dependent on slower, recurrent processes.
  The most important prediction of rapid-chase theory is that the feedforward sweeps of prime and target signals should occur in strict sequence. This strict succession should be observable in the time-course of the motor response, and there should be an early phase where the response is controlled exclusively by the prime and is independent of all properties of the actual target stimulus. One way to check these predictions is to examine the time-course of primed pointing responses. It has been shown that these pointing responses start at a fixed time after presentation of the prime (not the actual target) and start to proceed in the direction specified by the prime. If prime and target are inconsistent, the target is often able to reverse the pointing direction "on the fly", directing the response into the correct direction. However, the longer the SOA, the longer the time where the finger is moving in the direction of the misleading prime. Schmidt, Niehaus, and Nagel (2006) could show that the earliest phase of primed pointing movements exclusively depends on properties of the prime (e.g., the color contrast of red vs. green primes), but is independent of all properties of the target (its time of occurrence, its color contrast, and its ability to mask the prime). These findings could be confirmed with different methods and different types of stimuli.
  Because rapid-chase theory views response priming as a feedforward process, it maintains 
caption: Fig. 4: A schematic depiction of rapid-chase theory.[14] Primes and targets are engaged in a chase through the visuomotor system (from visual to motor areas). Because the prime signal has a head-start over the target signal, it is able to start a motor response assigned to it and to control this response for as long as the prime-target SOA allows. When the actual target signal then arrives in the motor system, it can follow through with the response already activated by the prime (in consistent trials) or has to reverse the response (in inconsistent trials). Rapid-chase theory assumes that primes and targets elicit feedforward cascades of neuronal activation traversing the visuomotor system in strict sequence, without mixture or overlap of prime and target signals. Therefore, the initial motor response to the prime must be independent of all stimulus aspects of the actual target.
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