Affective Priming: Valence and Arousal

Introduction

Affect: Its Hypothesized 3-D Structure: Valence, Arousal and Control

It is widely held that emotion can be defined as a coincidence of values on a small number of relatively independent dimensions. This view is based on factor analyses conducted on verbal judgments indicating that the variance in emotional assessments can be accounted for by three major dimensions: the two primary dimensions being affective valence (ranging from pleasant to unpleasant) and arousal (ranging from calm to excited). A third, less strongly-related dimension was variously called ‘dominance’ or ‘control’. Dimensional views of emotion have been advocated by a large number of theorists over the years, including Wundt (1896), Mehrabian and Russell (1974), and Tellegen (1985). A more recent study (Fontaine et al. 2007) provides further experimental support for the dimensional view of emotion, suggesting that the following dimensions are needed to satisfactorily represent similarities and differences in the meaning of emotion words: evaluation/pleasantness (accounting for 35.3% of the variance), potency-control (accounting for 22.8% of the variance), activation-arousal (accounting for 11.4% of the variance) and unpredictability (accounting for 6% of the variance).

Complexity of Emotional Response: Dual Process Accounts

When an emotional state occurs one needs to distinguish between different components of the response and their influence on subsequent cognition and behaviour. There is a cognitive component which involves changes in perceptual, attentional and semantic aspects of emotion (e.g. subsecond affective priming effects and attentional biases). This can occur rapidly, automatically, and unconsciously and is assumed to involve valence information. There is also a ‘motor’ component which refers to activated motor programs and action tendencies (e.g. prepared reflexes, changed facial or postural expressions). This has can also occur automatically and unconsciously. There are also physiological components which involve underlying changes in emotion-related physiological responses (e.g. hormonal or cardiovascular state). Finally there is the experiential (phenomenological) component which refers to the conscious feeling. Theories of emotional influence on decision-making or behaviour differ in which components are believed to be critical.

The impact of an emotional stimuli is largely determined by the amount of time it can be processed. With minimum processing, the stimulus may evoke a non-specific orienting response and this response may depend on unexpectedness or salience (Ohman, Hamm & Hugdahl, 2000). Additional stimulus processing may lead to differentiation of valence, with negative stimuli inducing an avoidance response and positive stimuli inducing an approach response (Hamm, Schupp, & Weike, 2003; Lang, 1995). Also, as more features are extracted in processing and the stimulus is recognized in context, the resulting response becomes differentiated into a specific – subjectively felt – emotional state, and may involve cognitive (normative) evaluation, attribution and inference.

Baumeister and colleagues (2007), in their review of the literature, conclude that emotion functions as a dual process: an automatic, unconscious, fast-acting process involving simple valence and involved in approach and avoidance reactions, and a slow, controlled, conscious process which functions as an evaluative feedback mechanism, involving qualitatively experienced emotions and arousal. Consciously experienced emotion on this account does not typically cause behaviour in a direct way (unlike e.g. automatic approach or avoidance valence based responses), but provide evaluative feedback for cognition about actions, thereby promoting learning and altering the preferences and decision making underlying future actions in related contexts.

This is consistent with evidence that affect is processed through at least two parallel pathways (LeDoux, 1989; 1995). One pathway creates an immediate response based on innate and conditioned responses, running directly from the thalamus to the amygdala.  This ‘automatic affect’ pathway rapidly transmits a crude response to sensory features of a stimulus directly to the amygdala for immediate reaction. The second pathway involves elaborated cortical analysis of the meaning of the stimulus. The thalamus routes sensory information to the cortex, which activates associations to it and appraises its value. From there, this information is transmitted to the amygdala, which is involved in assessing its emotional significance.

Affective Priming

In a typical affective priming study, positive and negative prime stimuli (words or pictures) are presented for 200 ms and are followed by a positive or negative target stimulus after an interstimulus interval of 100 ms. This results in a stimulus onset asynchrony of 300 ms (SOA; i.e., the interval between the onset of the prime and the onset of the target). Results show that the time needed to evaluate the target stimuli as either “positive” or “negative” – or to classify the target stimulus as ‘word’ or ‘nonword’ – is significantly shorter when prime and target share the same valence (positive-positive or negative-negative; affectively congruent) as compared to trials on which prime and target are of opposite valence (positive-negative or negative-positive; affectively incongruent). These data can only be explained if one assumes that the affective valence of the prime is processed.  Semantic priming effects are known to have different time courses than affective valence-based priming effects. Affective priming occurs with 150 msec SOAs; with SOAs of 500-1000msecs affective priming is not observed. Semantic priming, on the other hand, can occur with much longer SOAs.

Affective priming has also been observed for subliminally presented affective primes – presented for 15msec with a backward mask, and not consciously perceptible (Winkielman, Zajonc & Schwarz, 1997).

The Role of Arousal In Automatic Emotional Responses?

The interactions of arousal and valence dimensions of affective stimuli in priming has not been investigated in the literature. It is widely held that affective priming is mediated by the amygdala and is involved in detecting ‘motivational/incentive’ meaning of stimuli for automatic approach and withdrawal reactions. Through its central nucleus, the amygdala  triggers the release of stress hormones (e.g., cortisol) through its effect on the endocrine command centers in the hypothalamus, and increases arousal and the activation of autonomic nervous system responses (e.g., galvanic skin response, pupil dilation, blood pressure). Through the basolateral nucleus, the amygdala influences motivated action through its projections to the nucleus accumbens, a key structure of the brain’s incentive motivation system (Schultheiss & Wirth, 2008). Although both function together, the two responses can be dissociated: motivated approach/avoidance reactions can occur without autonomic arousal, and vice versa. According to Damasio’s ‘somatic marker’ hypothesis  (1994;1996), bodily autonomic/arousal reactions are necessary to ‘mark’ stimuli as good or bad to guide subsequent decision making automatically, suggesting that arousal is necessary for affective priming, assuming that priming reflects the operation of the automatic ‘markers’.

The role of arousal in automatic affective priming effects is not clearly understood, and has not been systematically investigated. All existing affective priming studies do not control for the arousal dimension of emotion. Does a stimulus have to be intrinsically arousing to elicit affective priming effects (e.g. a laughing face) – consistent with the Somatic Marker hypothesis – or can a stimulus that is high in valence but low in arousal (e.g. sun bathing) also elicit affective priming, consistent with the evidence for dissociations of central nucleus and basolateral nucleus amygdala activation?

Experiment Series 1: Arousal x Valence Interactions in Affective Priming

We propose to do affective priming experiments – both supraliminal and subliminal – looking at the interactions of valence and arousal, using the Turkish Affective Norms Database TUDADEN.

Turkish Affective Norms Database (TUDADEN)

The Turkcede Duygusal Anlamsal ve Degersel Normlar (TUDADEN) (Smith & Gökçay, 2009). has been developed to provide a set of normative emotional ratings for a large number of words in the Turkish language. The goal was to develop a set of verbal materials that have been assessed in terms of the affective dimensions of valence (pleasant-unpleasant), arousal, and dominance/control, as well as word frequency.

Stimuli

Between 2007-2009 my research lab has normed the following sets of Turkish words from the TUBITAK database for our affective priming study:

High arousal, positive valence

High arousal, negative valence

Low arousal, positive valence

Low arousal, negative valence

High arousal, neutral valence

Low arousal, neutral valence

All controlled for semantic relatedness, word frequency and word length.

Affective Priming Experiments

We will use a lexicial decision affective priming paradigm to assess valence-arousal interactions. We will also use the International Affective Picture System to run the study with pictures. The experiments will invesigate the following combinations of factors:

Valence type x arousal type x SOA (150 x 1000msec) x presentation type (subliminal or supraliminal)

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References

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