The Role of Affective Styles and the Perception of Approach-Withdrawal

Emotions on Cerebral Asymmetry

Karyn A. Vacanti

St. Bonaventure University












Two hypotheses are used to explain how emotions are processed; the valence hypothesis and the approach-withdrawal hypothesis.The valence hypothesis states positive emotions are processed by the left hemisphere and negative emotions by the right hemisphere.There are contradictory results to support this.The approach-withdrawal hypothesis states approach emotions are processed by the left and withdrawal emotions by the right hemisphere.This study looked at individual differences in the form of affective styles.It was predicted that people with a negative affective style would process withdrawal emotions faster than approach, and positive affective people would demonstrate the opposite. It was found that approach emotions are processed the fastest by a positive affect in the left hemisphere.Withdrawal emotions were processed the quickest in the right hemisphere and by a negative affective style.











The Role of Affective Styles and the Perception of Approach-Withdrawal Emotions in Cerebral Asymmetry

The perception and processing of emotions is a complex procedure in the brain.Currently there are two hypotheses regarding which hemisphere, the right or the left brain processes which emotions.The most common one is the valence hypothesis.This states that the right hemisphere is dominant in the processing of negative emotions, and the left hemisphere is dominant for positive emotions (Rains, 2002).

††††††††††† The valence hypothesis does not have much support.Studies have shown contradictory results.A study that used normal men, with no brain damage, did not show this lateralization of the processing of emotions.It was not clear that all positive emotions are processed by the left hemisphere and all the negative emotions are processed by the right hemisphere.This particular study found a lateralization of negative emotions only.Sad facial emotions were seen as more expressive in the left visual field than in the right visual field (Asthana & Mandal, 2001).Visual fields are contra lateral to each hemisphere of the brain.Therefore objects presented to the right visual field go the left hemisphere of the brain, and objects shown to the left visual field are routed to the right hemisphere.There was no asymmetry of happy faces found.This is one study that shows results not conducive to the valence hypothesis.

††††††††††† A second study by Crews, Jr. and Harrison (1994) looked at cerebral asymmetry in facial affect perception in women who were depressed and non-depressed.It was hypothesized that women with a depressed mood would show significantly slower overall reaction times to emotional facial stimuli than non-depressed women, and sad faces would be identified quicker within the left visual field than the right visual field. This study found that depressed women have significantly quicker reactions times for sad images presented in the right visual field, left hemisphere, than non-depressed women.When presented to the left visual field, depressed women identified happy faces reliably more quickly than non-depressed women, and happy faces were also identified quicker in left than right visual field.Overall, for sad faces non-depressed women had significantly faster reaction times to sad faces shown in the left visual field.There was a lack of asymmetry in reaction times for sad faces in the left and right visual fields for depressed women.Depressed women processed sad faces relatively the same in both visual fields.††† The results yielded from the study do not support the researchersí hypothesis.There is no concrete evidence to show that emotions are processed by their hedonic value.Again this study provides contradictory support for the valence hypothesis.

††††††††††† The approach-withdrawal hypothesis is another way to describe how emotions are processed.The approach system facilitates appetitative behavior and generates certain types of positive affect that are approach-related, for example an emotion that occurs as an individual moves closer to a desired goal.The withdrawal system facilitates the withdrawal of an individual from sources of aversive stimulation or organizes an appropriate response to a threat (Davidson, Jackson, & Kalin, 2000).Not all negative emotions are identified as withdrawal related.Anger is an example of a negative emotion that can be associated with approach behavior.A study by Harmon-Jones and Allen (1998) looked at anger.The approach-withdrawal dimension rather than valence is thought to underlie the asymmetry because positive affective states are inferred to reflect approach tendencies and negative affective states are inferred to reflect withdrawal tendencies.Harmon-Jones and Allen (1998) decided to look at anger because individuals with high levels of approach motivation had high levels of positive affect as well.To test whether valence or direction underlies the asymmetry an approach motivational tendency with a negative valence needed to be tested.

††††††††††† Many researchers have studied the approach-withdrawal dimension of emotions.One study by Davidson, Ekman, Saron, Senulis, and Friesen (1990) found that activation asymmetry in the anterior cortical regions discriminates between positive and negative emotions that are associated with approach and withdrawal.For this study the participants were hooked to an EEG machine, and watched film clips.Two clips were positive and two were negative.All of the participants showed more right sided frontal activation during disgust versus happiness.The left side showed more activation for happiness versus disgust (Davidson et al., 1990).††† There is evidence from the study to support the approach-withdrawal hypothesis.

††††††††††† Lesion studies support the approach- withdrawal hypothesis.It has been found that individuals with damage to the right hemisphere are more impaired in the perception of facial emotions.Right hemisphere damaged patients in one study were significantly less accurate compared to left hemisphere damage patients in the perception of negative and withdrawal emotions than for positive and approach emotions (Mandal, Borod, Asthana, Mohanty, Mohanty, & Koff, 1999).Other studies have found that damage to the left hemisphere will lead to an increase in the incidence of depressive symptoms.This could be due to the fact that these people can process negative and withdrawal emotions more efficiently than positive and approach emotions (Davidson, Jackson, & Kalin, 2000).

††††††††††† Individual differences play an important role in the asymmetry of the prefrontal cortex.Specifically affective states influence hemispheric lateralization and the perception of emotions.Affective states are consistent individual differences in emotional regulation and reactivity.This is how one responds to emotional challenges, cognitive processes, and dispositional moods (Davidson, 2000).†† One study looked at how inducing approach-related positive and withdrawal-related negative affective states would affect the asymmetry in the prefrontal cortex.It was found that emotions like fear and disgust, withdrawal and negative emotions, increase relative right-sided prefrontal activation.The opposite pattern of activation occurred when an approach and positive affective state was induced.There is a tendency for individuals to react stronger to negative rather than positive stimuli because there is an evolutionary pressure to avoid harm (Davidson et al., 2000).In this respect it is important to study negative emotions that have an approach tendency.This would solidify the idea that emotions are processed based on their motivational nature rather than valence.It can be hypothesized that individuals with a negative affective style will process withdrawal emotions quicker in the right hemisphere than individuals with a positive affective style.Also approach emotions will be processed faster by people with a positive affective style opposed to a negative affective style.Finally the valence of the emotions, positive or negative, will not determine how they are processed; rather the approach-withdrawal dimension of the emotions will influence how quickly they are processed.






††††††††††† Fifteen male and female college students from the psychology department at St. Bonaventure University will be recruited for the study.The students will receive extra credit in one of their psychology classes for their participation.Since previous frontal brain asymmetry research has only used right handed individuals, this study will as well (Jacobs & Snyder, 1996)†††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††† ††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††Materials

††††††††††† To assess the affective style of the participants the Positive and Negative Affect Schedule (PANAS) will be used.This is a self-report emotion measure.The PANAS is a trait measure of negative and positive affect.It contains a total of 20 emotion descriptors.Ten of them assess the high activation pole of negative affect, and the other 10 assess high activation pole of positive affect.The GEN version of the PANAS was used because it allows respondents to indicate how they feel in general.The internal consistency reliability of the Positive and Negative Affect scales of the PANAS-GEN is .88 and .87 (Jacobs & Snyder, 1996).

††††††††††† For this study stimulus slides representing different emotions were chosen from the standardized series of Ekman slides.These slides show facial emotions of disgust, surprise, anger, and happiness (Fourie, 1995). Disgust, for example,is considered a withdrawal emotion because the withdrawal entails terminating the sensory input, which could be olfactory, oral, or visual (Davidson et al., 1990).†† Along with the expressive faces, there were also neutral faces of the same person to match the other slides.The pictures were displayed to the participants through an electronic tachistoscope that is capable of exposing the photographs from 1 ms to 1000 ms.One hundred fifty milliseconds was the exposure duration of each photograph (Asthana & Mandal, 2001).


††††††††††† The participants will be given the PANAS-GEN first.They were then divided into two groups of 30, one group with a positive affective style and the other with a negative affective style.Once this was completed they viewed the four emotions depicted on the faces on the slides.The participants were told to look through the central eyepiece of the tachistoscope and fixate their eyes at the central point after a ready signal.Next the slides, in a counterbalanced sequence, were shown in either the right or left visual field.The slides were counterbalanced through a Latin square. The slide with the emotional face was shown to one visual field and the neutral face was shown to the opposite visual field. Visual field was counterbalanced as well through ABBA counterbalancing.All together the participants saw 8 slides, two of each type of emotion.Each emotion was viewed once in the left and right visual field.The participants were to push the button of the visual field that contained the most emotional face.The reaction time was then recorded for each photograph the participants viewed.


††††††††††† It was found that in the right visual field a person with a positive affective style processed approach emotions on the average of 0.73 milliseconds.On the other hand someone with negative affective style processed approach emotions on average 0.79 milliseconds.Withdrawal emotions were processed 1.07 milliseconds by positive affective individuals and 0.84 milliseconds by negative affect people.In the left visual field approach emotions were processed at 0.89 milliseconds by positive affect people and 0.97 milliseconds by negative affect.Individuals with a positive affect averaged 0.85 milliseconds for processing withdrawal emotions, and negative affect people averaged 0.76 milliseconds.There was a significant interaction between affective style, visual field, and type of emotion.The F was equal to 0.473.There were also main effects of the type of emotion, approach or withdrawal, and of affective style.


††††††††††† These results support the hypothesis that individuals with a negative affective style process withdrawal emotion quicker than the approach, and positive affective style people processed the approach emotions quicker than the withdrawal.Also the results support the approach-withdrawal hypothesis.People tend to process emotions based on the motoric component rather than the valence dimension.The valence of the emotions had no bearing on how quickly they were processed.Approach emotions were perceived more rapidly in the right visual field, left cerebral hemisphere, and withdrawal emotions were processed faster in the left visual field, right cerebral hemisphere.The evidence from this study suggests that approach and withdrawal related systems are localized in different cerebral hemispheres.The left frontal hemisphere is implicated in approach related emotional behavior, and withdrawal related emotions are implicated in the right frontal hemisphere (Davidson, 1993).

††††††††††† This study supports the idea that emotions are processed based on whether the emotion is approach or withdrawal.There are implications for future studies.The study lacked empirical evidence to show which hemisphere of the brain was actually activated during the presentation of the photographs..An EEG or PET scan should be used so the experimenter can visually see what hemisphere is being activated during the task.Also participants with a negative affective style, increased right frontal activation, should demonstrate an increase in vulnerability to moods, emotions, and psychopathology associated with withdrawal.These individuals should be more susceptible to emotions of disgust and fear, should show more dispositional negative affect, and should be more prone to anxiety disorders, especially phobias, which include a strong withdrawal component (Davidson, 1993).This could be studied more in depth by eliciting specific mood states in the participants and to see how they react based on affective style.This study provides increased support for the approach-withdrawal hypothesis, but there are still many aspects of emotional processing and affective style that needs to be studied.
















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