The previous section dealt with responses to single emotional stimuli that inform about a certain motivational state of the individual. These motivational states can be experimentally manipulated. The current section emphasizes influences from these manipulations on (experimentally) observable behavior. A huge body of empirical examples in that field is given within so-called priming paradigms. As one of the below described studies follows the affective priming paradigm, the theoretical background as well as previous evidence is outlined in the current section.
What is (affective) priming?
Priming has been described in general as faster processing of a certain stimulus when the processing occurs in context of an associatively related stimulus (De Houwer et al., 2002). More specifically, affective priming is defined as shorter evaluative or lexical decision latencies for affectively congruent prime target pairs (Wentura, 2000).
Respective facilitated responses are found in semantic priming for semantically related prime target pairs. The paradigm based initially on the idea of spreading activation within a semantic network as described below (Wentura, 2000). That is, semantic priming refers to the „benefit in processing a target word that is preceded by a semantically related prime word, relative to a condition with an unrelated prime (Wentura, 1999). For both affective and semantic priming, the nodes within the assumed network symbolize the different concepts whereas the links in between symbolize either associations between these concepts or semantic relations (Wentura, 2000). As the below outlined experiment is designed as affective priming paradigm, the following paragraphs emphasize affective priming.
Introduction to (affective) priming research
Affective priming research can be structured along three dimensions. First, the affective congruence effect was investigated, e.g. by using the evaluation task as in section 8. Furthermore, other methodologies have been used that are also popular in semantic priming, such as lexical decision tasks (word-nonword decision), the pronunciation task (to say the target word aloud), and the Stroop-priming (to name the color of the target). Besides the first dimension, materials used as primes and targets have been broadly varied, e.g. words (noun-noun, adjective-adjective, noun-adjective, and so on), pictures, or even odors. Third, the role of the stimulus onset asynchrony (SOA) has been widely investigated and divided into short (300 ms or less) and longer SOAs (Wentura, 2000). Results for the different kinds of priming paradigms are very mixed (Wentura, 2000). Hence, giving a summary of priming research seems to be a challenge (see also section 8.1), as the number of both paradigm variations and assumed mediating and moderating mechanisms is high.
Within the last years, an ongoing debate emerged about the assumed mechanisms involved in affective (and semantic) priming that mediates the observed response facilitation or inhibition. The discussion started with the fundamental publication of Fazio, Sanbonmatsu, Powell, and Kardes (1986), who ran three experiments and aimed at testing the attitude accessibility hypothesis. That hypothesis postulates that the mere presentation of highly arousing affective words automatically increases the accessibility of the corresponding affective evaluation. Thus, the authors presented positively and negatively valenced adjectives as targets. The subjects were asked to evaluate the target as positive or negative. Each trial comprised a positively or negatively valenced noun as
prime. The strength of the prime was manipulated in that subjects were asked to evaluate if the noun is positive or negative prior to the experiment. In the experimental phase, strongly (very short response latencies) and weakly associated primes (longest reaction times) were presented individually (experiment I) or in a similar list for all subjects (experiment III). In addition, SOA was varied with 300 and 1000 ms (experiment II). Summarizing all three experiments, decision latencies were shorter when prime and target words were affectively congruent (even for weak primes). The results have been repeatedly replicated in the following years (Bargh, Chaiken, Govender, & Pratto, 1992; De Houwer, Hermans, & Eelen, 1998; Hermans, De Houwer, & Eelen, 1994; K. C. Klauer, Rossnagel, & Musch, 1997).
Bargh and colleagues (1992) investigated the pervasiveness and conditionability of priming effects in three experiments. The authors presented adjectives and attitude objects previously rated in an evaluative decision task with a 300 ms SOA. Results suggested that the priming effect is a pervasive and relatively unconditional phenomenon. This is in line with Fazio et al.’s (1986) attitude accessibility hypothesis and suggests an automatic activation of an objects’ representation by its mere presentation. Two years later, Hermans and colleagues (1994) replicated the Foa and colleagues’ (1986) study presenting 100 both affectively polarized pictures as primes and targets. Healthy students performed both an evaluative decision task (experiment I, SOA 300 and 1000 ms) and a pronunciation task (experiment II). Both variations replicated the earlier findings, but only for 300 ms SOA. Klauer et al. (1997) aimed at testing whether evaluative and semantic priming follow the same laws. For evaluative priming that parallels the below described study, the authors report priming effects for 0 ms and 100 ms SOA. A series of experiments run by De Houwer and colleagues (1998) suggested several effects with words and nonwords (SOA 300 ms and 1000 ms):
Previous results were further replicated within an evaluative decision task. Affective priming occurred only for word-word pairs, but not for nonword-word pairs. However, affective (the learned meaning was affectively valenced) priming and identity priming (when nonwords were paired with its learned synonym) effects also emerged for nonwords for which a meaning has been previously learned. Priming effects were again restricted to 300 ms SOA.
Underlying mechanisms in (affective) priming: general assumptions
Generally, Klauer and Musch (2003) summarize three basic assumptions in affective priming. First, primes are assumed to influence the preactivation of relevant target connections within a lexical or semantic network. Second, irrelevant evaluations (e.g., evaluative decisions) influence the observable answer. Last but not least, irrelevant evaluations lead to an effect in the sense of a bias for positive or negative answers. An additional central concept in (affective) priming consists in the assumed affective-matching-mechanism (K.C. Klauer & Musch, 2003). This mechanism suggests further three assumptions and is of central interest for the current study:
1. The evaluation of prime and target is activated automatically. In addition, both evaluations are compared to each other automatically, independent of the experimental tasks.
2. Evaluative consistency of two words leads to a sense of plausibility. Inconsistency in contrast provokes a feeling of implausibility.
3. A spontaneous feeling of plausibility facilitates affirmative answers, whereas implausibility in contrast inhibits affirmative answers.
The term evaluative consistency refers to word pairs for which affirmative or dismissive answers are required. For lexical decision tasks, for instance, participants have to decide whether a stream of letters is an existing word or not. In this case, a “yes, word” answer is considered as affirmative and is thus facilitated (assumption 3) for evaluatively consistent prime target pairs (assumption 1) by a feeling of plausibility (assumption 2). The “yes, word” response is inhibited in contrast for evaluatively inconsistent prime target pairs (assumptions 2,3). Thus, although the evaluation of prime and target are irrelevant for the described task, this automatic process as well as the comparison of the evaluation of prime and target influence the measurable experimental behavior of the subject; a phenomenon, which is explained by the affective-matching mechanism (K.C. Klauer & Musch, 2003). Wentura (1998; 2000) as well as Klauer and Stern (1992) confirmed these assumptions amongst others with a lexical decision task. The respective expectations for an evaluative decision task which is used in the current dissertation is outlined in section 8.1.
Underlying mechanisms in (affective) priming: spreading activation versus judgmental tendencies
The complex pattern of effect expectations and respective empirical evidence (see below) constitutes the point of origin for the different assumed mechanisms underlying affective priming. The mentioned debate concerning possible underlying mechanisms comprises mainly three perspectives that are not necessarily exclusive: the spreading activation model, the judgmental tendency model, and Stroop-like mechanisms. All of them will be described in more detail in the following paragraphs.
Spreading activation models have their origin in several assumptions: According to the accessibility hypothesis, the perception of the prime activates the respective representations within a lexical or semantic network. It is further postulated that the representations of related concepts are connected. Via these connections, activation is supposed to spread within the network. As described above, Fazio et al. (1986) showed that less time is needed to categorize a target as positive or negative, when the target was preceded by a prime of the same valence compared to a prime with a different valence. The activation of the prime representation is hypothesized to spread along the interconnections within the network and to preactivate the representations of evaluatively consistent targets. Hence, the processing of all targets that are evaluatively consistent with the prime is facilitated (De Houwer et al., 2002; K.C. Klauer & Musch, 2003). Thus, priming studies seem to be well applicable to investigate semantic or associative network models, such as proposed by Lang and colleagues (1979) for the associative fear structure.
But in the last years, evidence suggested some effects that do not confirm the spreading activation model (K.C. Klauer & Musch, 2003): Affective priming effects are strongly dependent on the task. Affective priming effects were reduced and even inverted for dismissive answers within tasks that require either affirmation or negation from the participant (K.C. Klauer & Musch, 2003; K.C. Klauer & Stern, 1992; Wentura, 1998, 2000). List-context effects are additionally difficult to explain within the spreading activation model (Greenwald, Draine, & Abrams, 1996; Wentura, 1999).
Wentura (1999; 2000) takes into account that the obtained affective priming effects could be explained by the spreading activation mechanism, but that other explanations are possible, too: response facilitation or respectively interference (that is:
Stroop-like processes), and the judgmental tendency mechanisms. However, affective priming effects in lexical decision task suggest that at least parts of the spreading
activation mechanism seem to apply, as these effects are hard to explain by Stroop-like processes. In that kind of task, congruent and incongruent primes obviously do not have a different relevance to assign the target as word or nonword (Wentura, 2000).
However, these results could alternatively be explained by judgmental tendency mechanisms, as e.g. proposed by Klauer and Stern (1992). The authors assume a three-component process when subjects have to evaluate e.g. statements like “... (noun) is ...
(adjective)”: The affective components of prime and target are assumed to be activated first. An automatic comparison process occurs in a second step its affective compatibility. This comparison is meant to result in an a priori hypothesis about the correct answer. That is a tendency to give an affirmative or dismissive answer. Only in the third step, the relevant information for the task is retrieved in a controlled way, influenced in its retrievability by the a priori hypothesis.
According to the judgmental tendency model, Klauer and Stern (1992) argue that an automatic tendency for positive answers emerges if prime and target have the same valence. Klauer and Stern (1992) investigated how attitudes (e.g. trait ratings) bias memory-based judgments in two experiments. The experiments presume on the one hand that an attitude assigned to an object is automatically activated. The same is postulated for the affective evaluation of the trait. Both are further automatically compared to each other for affective consistency. The automatic process results in either affirmative or negative answer tendencies. Klauer and Stern (1992) presented pairs of person names and trait adjectives in a grammatical judgment task: The presented pairs were mixed as person-trait, person-person, and trait-trait. It was predefined that only the first combination is “grammatically correct” for one group and as “false” for another group. The person names were well-known European politicians thus providing most probably a variety of personal attitudes. Results suggested that “correct” answers were facilitated for affectively consistent pairs, whereas inconsistent pairs biased “false”
answers. Klauer and Stern (1992) demonstrate in a second experiment that these answer tendencies are enhanced under time pressure. Thus, uncomfortable conditions raise the impact of automatic processing.
Wentura (1998) aimed at further clarifying if affective priming is rather due to the spreading activation hypothesis or the model of judgmental tendencies. If the spreading activation mechanism applies, reactions to affectively valenced targets should be faster if the target is preceded by an affectively congruent prime. According to the model of judgmental tendencies, affectively congruent prime target pairs facilitate affirmative
responses, whereas affectively incongruent prime target pairs facilitate dismissive responses. Reaction times should thus be only enhanced for congruent pairs, if the required answer matches the judgmental tendency.
To test both models, Wentura (1998) presented words and pseudo words to a huge sample (n = 91). Half of the subjects was instructed to answer “yes” for words and the other half “no” for pseudo words. The respective other stimuli should be ignored.
Priming effects were indeed only found for the affirmative group. The results thus argue for the model of judgmental tendencies. Two years later, Wentura (2000) published a comparable study: According to the spreading activation model, “yes” and “no”
answers should not be influenced except for affective congruence and incongruence.
The judgmental model predicts facilitation due to affective congruence only for “yes”
but not for “no” answers. This effect was again controlled by asking half of the subjects if the target is a word (thus requiring “yes”) and to ask the other half for pseudo words (thus requiring “no” for words). According to the judgmental theory, the affective priming of the answer “word = no” should be less pronounced. The author presented 96 semantically unrelated noun-adjective and noun-nonword pairs, respectively. The results replicated the previous evidence and suggested the judgmental tendency model, although the effect was rather small in both studies.
Wentura (2000) concludes that the spreading activation and the judgmental tendency model do not exclude each other as one model focuses on the facilitation of access and the other the facilitation-inhibition of answers. As Wentura (2000) points out, both effects occur in different stages of information processing. Wentura (1999;
2000) further emphasizes that particularly affective priming studies using words in evaluative decision tasks are very likely to facilitate affirmation tendencies for affectively congruent prime target pairs and to facilitate negative answers for incongruent prime target pairs. This will be of particular interest for the current study.
Klauer and Musch (2003) summarize the evidence as well as theoretical considerations in a model of the evaluative system and postulate a preconscious evaluation activity. This evaluation, once activated, influences subsequent processes via e.g. Stroop (e.g., De Houwer et al., 2002) or affective matching mechanisms. However, questions such as the goal dependence of the irrelevant evaluations and a comparison between evaluative and cognitive processing still remain to be answered.
Despite of all debates about the mediating mechanisms in affective priming, Wentura (2000) presumes an agreement in that the presentation of a stimulus automatically activates the valence of a stimulus.
Additional questions in affective priming
Besides the debate about the underlying mechanisms, some additional questions are of interest in affective priming research. The following paragraphs will briefly respond to questions concerning controlled versus unconscious processing, the role of subjective appraisal processes, associative strength, and the SOA duration. This is of particular interest for the current study, as the assessment for subjectively altered stimulus appraisal on very early and uncontrolled stimulus processing levels is intended.
Do primes have to be processed in a controlled manner? Greenwald and colleagues (1996) demonstrated that unconscious activation of meaning is possible since subliminally presented and masked primes are able to affect target processing, too.
Subjects had to categorize either affectively polarized words as pleasant or unpleasant or first names as male or female. Nevertheless, this is only found under particular conditions: Priming effects occurred only when targets followed the prime within 100 ms. Furthermore, in contrast to supraliminally presented prime target pairs, subliminally presented pairs did not influence subsequent prime target pairs. Thus, unconscious priming is possible but of very short duration.
A few years before, Murphy and Zajonc (1993) have already shown that affective priming occurs in particular for extremely briefly presented primes (facial expressions and Chinese ideographs): In a comparison of affective and cognitive priming, the authors found affective priming to be more expressed in very brief prime presentations (4 ms) and cognitive priming in longer prime presentations (1000 ms). The authors thus reasoned that affective reactions can be evoked with minimal stimulus input (Murphy &
Zajonc, 1993). Thus, individuals are able to make reliable affective discriminations with minimal exposure times.
Moors, De Houwer, Hermans, and Eelen (2005) as well as Fazio (2001) additionally emphasize the impact of subjective appraisal processes and claim that the intrinsic valence of a stimulus is crucial for further stimulus processing: Empirical examples for automatic processing of intrinsic stimulus valence have been described above for e.g. Bargh et al. (1996) or Fazio et al. (1986). Thus, evaluations of the primes emerge automatically during experimental presentation, a process that is assumed to be
rapid (e.g., Fazio et al., 1986; Hermans, De Houwer, & Eelen, 2001) and evoked without consciousness (e.g., Bargh et al., 1996).
Has associative strength a moderating role in associative priming? As described above, participants were instructed to name an attitude for objects as quickly as possible (Fazio et al., 1986). Associative strength was operationalized by the reaction time.
Indeed, affective priming was only found for strongly associated primes. Continuing this idea, Fazio et al., (1986) tried to experimentally manipulate associative strength of the prime by an attitude rehearsal task in which the subjects expressed their attitudes toward the object multiple times. Again, the affective priming effect in a word structure (one-syllable) evaluation task was found to be more pronounced for the rehearsed primes (Fazio et al., 1986). This was taken as final evidence that the priming effect depends upon the subjective evaluation of the stimuli. For a discussion about the time course of assessing associative strength and the priming procedure, see the argumentation of Bargh, Chaiken, and Fazio (1992), Chaiken and Bargh (1993), and Fazio (2001).
Hermans, De Houwer, and Eelen (2001) explicitly investigated the role of SOA length (-150, 0, 150, 300, and 450 ms) in both an evaluative decision task and a pronunciation task. The authors aimed at answering whether priming is actually due to automatic processes. To avoid random answers, the consistent/inconsistent proportion was shifted from usually 50/50 to 75/25. The authors presented subjectively rated words (most positive vs. most negative) as primes. The authors argue that it is a strong indicator for an automatic nature of activating affects or attitudes if affective priming is reliably observed at SOAs of 300 ms, but not for SOAs of 1000 ms. Similarly, Fazio (Fazio, 2001) concludes that the affective priming effect is only found for shorter stimulus onset asynchrony (SOA), 300 ms for instance. For SOAs of 1000 ms, the affective priming effect was not found (Fazio, 2001).
In summary, affective priming is a well investigated empirical phenomenon. It has to be consequently judged as valid and reliable method to experimentally manipulate the initially mentioned motivational state of subjects and to observe its influences on the action disposition.
(Affective) priming in clinical samples
The most probable benefit of priming paradigms is to provide insights in the processing of disorder-related and unrelated stimuli. The design has been applied in
several clinical samples. For instance, schizophrenic, depressive, anxiety disorder patients and PTSD patients in particular have been investigated. The following paragraphs summarize finding among clinical samples ensued by a subsection considering previous PTSD studies.
For schizophrenic patients, indicators of an altered semantic and affective priming patterns have been found in schizophrenics with mild thought disorders (Lecardeur et al., 2007) and subjects with sub-clinical symptoms of psychosis (van't Wout, Aleman, Kessels, Laroi, & Kahn, 2004). Most recently, Lecardeur and colleagues (2007) investigated 15 chronic schizophrenics with mild thought disorders according to the Positive and Negative Syndrome Scale (PANSS) and the Thought Language Communication Scale as well as 15 healthy controls in a semantic priming paradigm.
The authors presented related and unrelated prime target pairs (nouns) with a SOA of 250 ms and 500 ms, requiring a lexical decision task. Indeed, a hyper-priming effect was found for the schizophrenics, which was mainly due to enhanced response
The authors presented related and unrelated prime target pairs (nouns) with a SOA of 250 ms and 500 ms, requiring a lexical decision task. Indeed, a hyper-priming effect was found for the schizophrenics, which was mainly due to enhanced response