Response Priming

The term response priming or Reaktionsbahnung is called a special form of priming in the psychology of perception. Generally consist priming effects that the reaction ( engl. response) to a target stimulus ( engl. target) from the previous presentation of a Bahnungsreizes (English prime ) is affected. The specificity of the response priming is that both stimuli follow each other very quickly and are linked to motor response alternatives. If a subject performs a quick response to classify the target stimulus, a short time before appearing Prime trigger response conflicts when he is assigned to another response alternative than the target stimulus. This response conflicts are reflected in the behavioral data in the form of so-called priming effects low, such as in response times and error rates. A special feature of response priming effects is their independence from conscious perception ( visibility ) of the Primes.

Response priming effect as visomotorischer

As early as 1962 reported Fehrer and Raab experiments in which subjects were asked to respond to the appearance of a stimulus as quickly as possible by pressing a single button, its visibility by so-called metacontrast masking (see below) has been greatly reduced. They found that the reaction time was independent of the conscious visibility of the stimulus, ie to highly visible stimuli was also reacts quickly to barely visible stimuli ( Fehrer -Raab effect ). The term response priming used were primed in 1982 for the first time Rosenbaum and Kornblum in connection with an experimental paradigm in which parts of motor responses by primes. The modern method of response priming was in the 80s and 90s by Peter Wolff, Werner Klotz, Ulrich Ansorge and Neumann Odmar at Bielefeld University entwickelt.Eine Another important development occurred in the mid -90s by the working group to Dirk Foothill at the Technical University Braunschweig.

In experimental paradigms, using the method of the Response priming, subjects have to respond to a specific target stimulus. In a simple experiment, it could be explained by one of two geometric stimuli, the two corresponding response keys are assigned (eg diamond - left button, square - right button). The experiment will consist of many successive passages in which the subject must always press left on publication of a diamond and the right at appearance of a square. Doing a Prime, which also have the response -inducing properties of the target stimulus appears in each passage shortly before the presentation of the target stimulus, so even a diamond or a square (Fig. 1a). Are prime and target with same reactions linked (diamond follows rhombus, square to square), they are considered to be consistent (or " congruent ", " compatible "); they are associated with different responses (hash followed by square, square to diamond), as inconsistent (also called " incongruent ", " incompatible"; Fig. 1b). The time interval between onset of the prime and onset of the target stimulus is called stimulus onset asynchrony (SOA). SOAs are used typically of approximately 100 ms (milliseconds) or less.

Priming effects occur when the prime affects the motor response to the target stimulus: consistent Primes accelerate response times, inconsistent Primes they decelerate ( Fig. 2). Priming effects in reaction times are usually determined as the difference between the mean reaction times in the consistent and inconsistent passages. Additionally, consistent Primes only very rarely lead to response errors ( ie false responses to the target stimulus ), while the incidence of errors in inconsistent Primes can be very high. The priming effects increase in both the reaction times and the error rate is typically in the SOA, resulting in plots of typical scissor-like course of the effect. This means that the later the target stimulus following the Prime, the more influence the prime on the reaction times. At an average reaction time of 350 to 450 ms, the response priming effect may exceed 100 ms; he is thus one of the numerically largest effects of reaction time research.

Today is well established that the increase of the effect with the SOA is due to the fact that the Prime has more time to influence the reaction before the actual target stimulus can be motorized effective. This follows clearly from the analysis of the time course of motor activity in the EEG, in primed pointing movements, in force measurements and simulation studies. How big is the priming effect is, therefore, depends on both the stimulus characteristics and properties of the task. Primes with higher stimulus energy (ie, higher contrast, longer duration etc.) and functions with simple Reizdiskriminationen lead to large priming effects, while Primes with low stimulus energy and difficult discrimination tasks lead to reduced effects. Priming effects can be enhanced by visual attention is directed in time for presentation of the Primes on its position or its relevant characteristics.

The time course described applies to SOAs of up to about 100 ms. For longer SOAs, the effect may rise even further. Under certain conditions, but one can also observe a reversal of the effect, in the inconsistent primes lead to faster responses to the target stimulus as consistent Primes. This effect is often referred to as " compatibility negative effect."

Masked priming

Response priming can be used to investigate phenomena of unconscious perception. The conscious visibility of the Primes by a masking stimulus can be systematically varied to the point of invisibility of the Primes. This is done through the presentation of the mask shortly before or after the Primes. The visibility of the primes can be collected by various measures, such as Forced -choice discrimination, discovery rulings, brightness judgments and other gauges. In many response priming experiments, the target stimulus itself serves to mask the Primes ( Fig. 1). The so-called metacontrast masking is achieved by the Prime follows a mask that surrounds it, so that both stimuli have adjacent contours. A circle can be masked for example by a larger ring whose inner dimensions correspond to the external dimensions of the circle. Metacontrast is a form of visual backward masking, ie the visibility of the Primes is decreased by the presentation of a subsequent stimulus.

Figure 3 shows typical masking characteristics as a function of SOA, prime and target, the target stimulus serves as a mask. As a measure of conscious visibility of the Primes could here about the discrimination performance of a test person serve, which has the task to guess the shape of the Primes (diamond or square) in each passage. Without masking, the performance would be practically perfect: the subject could correctly name the Prime as a diamond or square problems in each passage. With complete masking of the prime power would, however, be at chance level (Fig. 3, left). In many experiments, however, result in less extreme masking curves (Fig. 3 right). The vast majority of the experiments leading to so-called type-A masking which is strongest at short SOA between prime and mask, and decreases with increasing SOA, so that the Prime is always easier to distinguish. Under certain conditions, it may also lead to Type-B masking when the masking effect is strongest at medium SOA, the Prime is however easier to distinguish at shorter or longer SOAs. Type-B masking can occur especially in metacontrast masking, however, depends sensitively on the properties of prime and mask. In addition, the masking curve from person to person can vary greatly.

Independence of response priming and visual awareness

Experiments show that the time course of the response priming effect ( increasing effect with increasing SOA) is independent of the timing of the mask. Klotz and Neumann (1999 ) demonstrated response priming effects in complete masking of the primes. Foothill et al. varied the time course of masking by altering the relative duration of Primes and target stimuli. Target stimuli were arrows that could point to the left or right, and Primes were smaller arrows that were metacontrast masked by the target stimuli. If the subjects had to decide in which direction showed the Primes, depending on condition, all illustrated in Figure 3 species could be generated by masking curves: complete visibility, complete masking, type A and type B masking masking. However, when the subjects were asked to respond as quickly as possible to the direction of the target stimulus, resulted in all conditions almost identical priming effects. The time course of these effects was always the same ( with the SOA rising), regardless of whether the primes were completely visible or completely invisible, no matter whether the visibility of the SOA decreased or removed. Priming effects may be increased so even if the visibility of the primes decreases. Such opposite time courses of priming and visual awareness of the prime show that both processes are based on different mechanisms. This finding was confirmed in many other experiments in which numerous dissociations between masking and priming effects revealed. The independence of priming and visual consciousness clearly contradicts the traditional view, according to the unconscious priming processes are at best a residual capability that remains to a small degree, if the visibility of the stimuli has dropped below a certain threshold. This view has repeatedly led to sharp criticism of the research to the unconscious or subliminal perception, but it is probably fundamentally wrong. Rather, the motor activation by masked primes apparently occurs independently of processes of backward masking, provided the visibility of the primes is determined only by the nature of the mask, while the prime stimulus itself remains unchanged. This means that visually unconscious ( hidden ) stimuli can, in a short period of time and under certain conditions, motor responses in the same manner affect how conscious stimuli.

Variants

Provided that one is clear about the role of certain influential variables, response priming can be used in numerous experimental variations and to investigate a variety of questions from cognitive psychology. The most commonly used form of using a prime and a target stimulus at the same screen position, the target stimulus serves as a mask (often on the principle of metacontrast masking ). In many experiments, two different target stimuli are shown simultaneously, preceded by two primes at the same positions. The subject must then distinguish the two target stimuli and react to the position of the target stimulus relevant to the task. Sometimes three kinds of stimuli are used ( prime, mask, target stimulus), especially when the SOA between prime and target must be very long. Sometimes even no mask. Prime and target must not be located at the same positions: A stimulus can also flank the other, as is the case in the Eriksen paradigm. The Eriksen effect could be of current knowledge, a special case of response priming.

Response priming effects have been demonstrated with a variety of stimuli and discrimination tasks, including geometric stimuli, color stimuli, different types of arrows, natural images (animals vs.. objects ), vowels and consonants, letters and numbers. In a study chess configurations were presented as primes and target stimuli, and the subjects had to decide whether the king was in check. Similarly, diverse types of masking were used. Some experiments measure instead of keypress responses ( mostly with two response alternatives done ) Talk reactions, targeted pointing movements, eye movements, or so-called readiness potentials that capture the motor activation in the brain and can be measured by methods of electroencephalography. Also, imaging techniques such as magnetic resonance imaging are used. Others use more than two experiments reaction alternatives. Mattler (2003) showed that response priming can affect motor actions not only, but also cognitive operations such as the shift of spatial attention or a change reaction-time tasks.

Theories

Here are three theories to explain the positive response priming effect are presented. For an overview of the explanations for the negative compatibility effect, see Sumner (2007).

Direct parameter specification

The theory of direct parameter specification ( "direct parameter specification"; Fig. 4 ) was developed by Odmar Neumann at the University of Bielefeld, to explain the Fehrer -Raab effect and the earliest response priming studies. This theory assumes that the subject at the beginning of the experiment acquires rules of the stimulus-response mapping, which are present after a short practice in automated form. Is this practice phase completed, the reaction can be prepared in advance so that only a single critical stimulus feature (eg, diamond vs. Squared) is necessary to initiate the reaction. This incoming stimulus feature then defines the last missing action parameter ( "action parameter", eg left vs. Reaction right ). The triggering action is fast and direct, without a conscious representation of the stimulus would be necessary. Response priming is explained that the Prime with its irritating properties exactly the same processes of direct parameter specification triggers that should only take place in accordance with instruction- by the target stimulus. Parallel to the response triggered in visomotorischen system creates a conscious representation of prime and target, which may be subjected to but processes of visual masking. However, the conscious representation plays no role for the motor response on Primes and target stimuli in the current test run.

Action trigger approach

The " action triggers approach" ( engl. "action trigger account" ) was developed by Wilfried customer, Andrea Kiesel and Joachim Hoffmann at the University of Würzburg. This approach emphasizes that responses are initiated to unconscious stimuli either by semantic analysis nor by previously learned stimulus-response associations. Instead, it is assumed that a prime in an existing "action release condition" fit and thus the reaction triggers, much like a key that opens a lock. This always occurs in two successive steps. First, be kept to an expected or known task "action triggers " in working memory active, which should trigger a specific motor response. This "action triggers " are formed in the instruction and practice phase of the experiment. Called In the second step, " online stimulus processing", it is compared whether a stimulus shown fits into a well-known scheme. If this is the case, the associated response is automatically triggered. An example would be the task to tell whether a proffered number is greater or less than five: at present the numbers "1 " to "4 " should be pressed the left button at the presentation of the numbers "6" to "9" the right. As a result of the instruction to be "action triggers " are formed, which automatically cause the corresponding reaction after the presentation of the relevant stimulus. An important prediction of this theory is that reactions can also be triggered by primes which, although even never occur as the target, but satisfy the trigger conditions.

Again, the conscious representation of the stimulus is irrelevant for the current motor activation; but it can lead to in later passes of the experiment response criteria be changed strategically (for example, in order to avoid response errors ). Overall, this theory can be seen as a further development of the concept of the direct parameter specification.

Rapid Chase theory

The "rapid - chase theory " was introduced in 2006 by Thomas Schmidt, Silja Niehaus and Annabel nail. It links the model of direct parameter specification with the observation that newly appearing visual stimuli trigger a wave activity in visomotorischen system that quickly spreads from visual areas through to motor areas. Since the propagation speed of this activity wave is very high, Victor Lamme and Pieter Roelfsema have set up by the University of Amsterdam, the thesis that there is first provided a pure feedforward process ( feedforward sweep): A cell that is first reached by the wave front, must have its activity to pass without being able to integrate previously feedback from other cells. At the same time Lamme and Roelfsema assume that such a feedforward processing alone is not sufficient to give rise to visual awareness of a stimulus: these are feedback processes and recurrent (recurrent ) processing loops necessary, even the most distant areas of the brain can connect with each other.

After the rapid -chase theory prime and target successively solve such " feedforward sweep ", which eventually reach motor areas of the brain. There succession motor processes are triggered; also a trip occurs automatically and without awareness. As the Prime has a head start to prime and target provide a " chase " ( "rapid chase" ) by the visomotorische system. Since the prime signal reaches the motor cortex first, it initiates the motor response associated with it. The shorter the SOA, the sooner, the target stimulus signal take up the chase. Only when the target stimulus signal has also arrived in the motor cortex, it may be the motor reaction to continue (if it is consistent with the Prime) or redirect (if it is inconsistent with the Prime). This can be explained in that response priming effects with the SOA rise: The longer the SOA, the longer prime the reaction alone control, and the farther he can steer the reaction process in a certain direction. If necessary, the Prime can also provoke an error ( it is the most frequently observed priming effects in the error rates found ). Such a sequence of motor activation by prime and target has already been described in 2003 by Dirk Foothill and employees in a mathematical model and is also consistent with early EEG findings for response priming match. Response priming effects are independent of visual awareness, according to the Rapid Chase theory because they are supported by rapid feedforward processes, while the emergence of a conscious representation has to rely on slower, recurrent processes.

The most important prediction of the rapid -chase theory is that the feedforward sweep of prime and target should be carried out strictly sequential. This strict sequence should be reflected in the time course of motor responses, and there should be an early period, in which the reaction is controlled solely by the Prime, but is independent of any properties of the actual target stimulus. Particularly well be examined on the basis of the time course of primed pointing movements these predictions. This shows that the pointing motion at a fixed time after the appearance of the Primes (not the actual target stimulus ) and starts first takes place in the direction of the Primes. When prime and target are inconsistent, the target stimulus can reverse the pointing direction " in flight " and steer you in the right direction; the longer the SOA, the longer and further moves the finger in the direction of misleading Primes. Schmidt, Niehaus and nail were able to show that the earliest phase of such primed pointing movements only on properties of the Primes ( here the color contrast of red versus green Primes ) dependent, but not by characteristics of the target stimulus ( the time of its appearance, its color contrast or its masking effect ). These findings were confirmed with different methods and stimuli.

Since the Rapid Chase theory Response priming regarded as a feedforward process, it assumes that the priming effects arise before recurrent and feedback processes can engage in the processing. Therefore, the theory provides the controversial thesis that response priming effects are a measure of the preconscious processing of visual information, which may differ fundamentally from the representation of stimuli in the visual consciousness.