Interhemispheric interaction and degree of handedness in relation to social, political, gender, and philosophical beliefs in undergraduates

Research has suggested that brain hemispheres play different roles in processing belief systems, the RH serving to update beliefs while LH acts to hold beliefs constant (Ramachandran, 1995). Degree of handedness is thought to be directly related to amount of interhemispheric interaction in the brain (Christman, 2001). Niebauer (2004) correlated degree of handedness with beliefs in creationism and evolutionism, finding that mixed-handers ascribed to the more progressive belief of evolutionism, and strong-handers to the more conservative belief of creationism. The current study replicated Niebauer’s study and additionally sought to find similar correlations between mixed-handedness and progressive beliefs in the areas of egalitarianism, political ideology, and moral traditionalism. No significant correlations (merely several trends) are established between handedness and belief systems. Handedness and Belief Systems 3 Interhemispheric interaction and degree of handedness in relation to social, political, gender, and philosophical beliefs in undergraduates Cerebral Lateralization and Belief Systems The findings of cerebral lateralization research indicate that there is substantial evidence that the two brain hemispheres have different and nearly opposing roles in creation of beliefs and functioning of belief systems. Some of the earliest research came from the clinical setting, as Rausch (1977) reported on hypothesis testing of patients who had surgical excisions of either the right or left temporal lobe. Those with right hemisphere surgical excisions preserved certain hypotheses even when they were proved incorrect, while patients with left surgical excisions were observed to alter from a specified hypothesis even when it was shown to be correct. Those for whom the left hemisphere was intact appeared to attempt to maintain their current beliefs (in this case a hypothesis) and those for whom the right hemisphere was intact appeared to update and change their beliefs. This study was an early suggestion of a model of hemispheric specialization in belief maintenance and revision, the left hemisphere acting to hold constant or maintain current beliefs, and the right hemisphere acting to revise and update beliefs. Ramachandran (1995) discussed how this can help explain anosgnosia in right hemisphere parietal lobe damage, explaining that those with the damage may lack the right hemisphere’s ability to update their current health situation to include their illness, resulting in denial of their affliction. Drake & Bingham (1985) used lateral orientation in an experimental setting to investigate the relation between persuasion and cerebral hemisphere activation. Hemispheric activation was accomplished by playing a counterattitudinal message in either the left or right ear while the participants filled out response measures and had their body turned in the direction of the Handedness and Belief Systems 4 message. Results indicated that those induced to turn toward the left (right hemispheric activation) were more influenced by the message, indicating that the right hemispheric may have a role in openness to persuasion (updating beliefs), and the left hemisphere in resisting persuasion (belief perseverance). These findings were supported by Drake’s (1988) finding that activation of the left hemisphere resulted in more consistent results on personality scales than did activation of the right hemisphere. EEG activation was used by Cacioppo, Petty, & Quintanar (1982) to correlate hemisphere activation and persuasion. They found that as participants thought longer and longer about a certain argument, EEG activation shifted from the left parietal area to the right parietal area. Ramachandran (1995) suggested that these findings indicated a model of the brain where the hemispheres have opposite functions in regards to information interpretation and maintenance of beliefs. He proposed that the left hemisphere serves to keep beliefs constant in the face of the torrential flow of new information. The left hemisphere interprets the world by imposing logic and consistency, while the right hemisphere is an “anomaly-seeker”, detecting threats and inaccuracies in the consistency of the left hemisphere’s interpretations. This body of research suggests that the cerebral hemispheres play two distinct roles in belief updating and perseverance. While the exact mechanisms are not known, models have been advanced to explain the clinical and experimental findings. The left hemisphere appears to attempt to maintain beliefs, preserving consistency and resisting change, while the right hemisphere appears to act as a belief updater, challenging those beliefs held by the left hemisphere. As demonstrated above, this interaction and communication between the hemispheres is affected by lateral orientation and lesions of the hemispheres, but possibly other variables may affect the belief updating and perseverance process. Degree of handedness may Handedness and Belief Systems 5 be one such variable, as evidence exists demonstrating that the degree of handedness (stronghandedness versus mixed-handedness) may be indicative of interhemispheric interaction and the subsequent belief paradigm. Handedness and Interhemispheric Interaction The term interhemispheric interaction refers to the amount of information transfer between the hemispheres, as evidenced often by information sharing between hemispheres on cerebral lateralization tasks. There has been much speculation and research on the relation between handedness and interhemispheric interaction, and the findings have been inconsistent. A few studies have found more interactions in right-handers. For example, Miller (1983) found that left-handers displayed more hemispheric independence in laterally displayed configurational word processing. Research also exists finding no difference between hemispheric processing between right-handers and left-handers. Banich, Goering, Stolar, & Belger (1990) used digitmatching and letter-matching tasks, presenting items to one or both hemispheres and requiring participants to decide if the digits or letters had been used in the previous word or digit presentation; findings indicated no relationship between handedness and interhemispheric interaction. In 1975, Beaumont & Dimond found similar results, using abstract shape matching across hemispheres as a function of exposure duration. Patterns of results indicated that righthanders did not differ from non-right-handers. Piccirilli, Finali, & Sciarma’s (1989) research also yielded no significant differences in a finger localization task intended to explore the efficiency of interhemispheric communication. Though dissenting studies do exist, the bulk of the research suggests that greater interhemispheric interaction exists in mixed/left-handers, as demonstrated in various ways. The term “mixed-hander” refers to individuals who generally use both hands for a variety of tasks Handedness and Belief Systems 6 and therefore do not meet the criteria for strong right-handedness or strong left-handedness. Potter & Graves (1988) demonstrated that interhemispheric transfer (as measured by motor and tactile tasks) was significantly higher in non-right-handers than consistent right-handers. In 1983, Verrillo reported mixed-handers differed from strong-handers in subjective magnitude of vibrotactile stimuli. Greater effect of interhemispheric delay in stimuli presentation for righthanded participants compared to left-handed participants was reported by Dimond & Beaumot (1972). Christman (2001) conducted a study demonstrating that mixed/left-handers exhibit greater interdimensional interaction by using centrally-presented stimuli with two dimensions (such as Stroop stimuli), each dimension being presented to a different hemisphere. Righthanders were superior at tasks that involved keeping the two dimensions independent (less Stroop interference) and left-handers were superior at integrating the two dimensions (judging if the color and word were the same). Christman & Propper (2004) demonstrated in recognition memory tests designed to test “knowing” (semantic memory) or “remembering” (episodic memory). Episodic memory is known to involve interhemispheric interaction, whereas semantic memory merely involves unihemispheric processing. Their results indicated that mixed-handers are biased toward basing recognition responses on judgments of “remembering” vs. “knowing” (as strong-handers are). Niebauer, Christman, Reid, & Garvey (2004) asserted that a contributing factor for the inconsistent findings may be due to the fact that handedness is defined in various ways. Some studies consider mixed-handers; others merely group into left-handers and right-handers, still others consider right-handers against all others. The mechanism by which these effects exist has not been fully discovered, but there is evidence of corpus callosum involvement. Habib, Gayraud, Oliva, Regis, Salamon, & Khalil (1991), using a handedness questionnaire and magnetic resonance imaging techniques, found Handedness and Belief Systems 7 that “non-consistent right-handed” participants had significantly larger corpus callosums, especially in the anterior half. Witelson (1985) observed an 11% increase in size in mixed/lefthanders’ corpus callosums compared to strongly right-handers. Witelson & Goldsmith (1991) furthered research in this area and reported in right-handers a correlation of -0.67 between degree of hand preference and corpus callosum size, signifying strong evidence that mixed-handedness is associated with a thicker corpus callosum (and also its ithsmus). Christman (1995) proposed a mechanism by which amount of sinistrality (left-handedness) is associated with a thicker corpus callosum and therefore less lateralization of brain function, suggesting that the increased callosum size may indicate a greater interhemispheric interaction in left-handers. The current study will focus on the mixed-handers versus strong right-handers, as left-handers make up little of the population, approximately 10% (Perelle & Ehrman, 2005), and strong lefthanders comprise about 2%-3% of the population (Lansky, Feinstein, & Peterson, 1988). Also, the research supports the same differential effect for mixed-handers as for left-handers (Christman, 2001; Verrillo, 1983). Along with assessment of personal handedness, the presence of familial sinistrality (FS+) is important as well. Christman & Propper (2001) found that in experiments involving handedness’ effect on interhemispheric processing of episodic memory, those having immediate family members that are left-handed produced greater evidence of interhemispheric interaction (as evidenced by demonstration of superior episodic memory and inferior implicit memory). This finding is important for the current study as well and will be taken into account as a variable. Mixed-handedness, Belief Systems, and Social Attitudes The relation between handedness and systems of belief has been extensively researched by Niebauer et al. (2002, 2004) in two sets of studies. The studies test and support a model by Handedness and Belief Systems 8 which mixed-handedness is associated with greater interhemispheric interaction and greater contact with the right hemisphere, which serves to update beliefs, compared to the left hemisphere, which serves to keep beliefs constant (Ramachandran, 1995). Niebauer, Aselage, & Schutte’s (2002) first set of studies involved sensory systems and utilized Botvinick & Cohen’s (1998) “rubber hand illusion.” The rubber hand illusion involves the participant placing their hand out of sight (possibly below a table) and placing a rubber mannequin hand in plain view directly above their hidden real hand. The hidden real and visible fake hand are then both touched lightly by an experimenter (using a brush or finger) simultaneously and in corresponding places. This procedure is repeated for a short period of time, the conflicting sensory information eventually giving the participant the illusion that the rubber hand is his or her own. Niebauer et al. assumed that this illusion was the result of the right hemisphere’s detecting anomalous information and using that information to update the left hemisphere’s belief system. Results were as predicted, as mixed-handers experienced this effect to a greater intensity then strong-handers. Findings were supportive of this model by Niebauer et al.’s (2002) replication of the rubber hand study, which found that mixed-handers also experienced the effect more quickly than strong-handers. This research seems to indicate that since less information may be required for a mixed-handed individual to change their belief system, mixed-handers may have a “lower threshold” for updating beliefs than strong-handers (at least for sensory systems). Niebauer et al.’s second set of studies (2004) involved beliefs concerning the origins of life. The study involved students filling out a questionnaire assessing handedness (using the Edinburgh Handedness Inventory [Oldfield, 1971]), familial sinistrality, and a four item creationism/evolutionism scale. Niebauer et al.’s (2002) “lower threshold” paradigm was Handedness and Belief Systems 9 hypothesized to produce results to the effect that mixed-handers ascribe to the theory of evolution and strong-handers to creationism. This hypothesis was shown to be true, supporting the presumption that in mixed-handers the right hemisphere’s anomaly detector may be more in touch with the left hemisphere because of interhemispheric interaction, making the creationismto-evolutionism paradigm shift all the more possible and efficient. But can Niebauer et al’s “lower threshold” paradigm be generalized to other issues as well? The current study intends to explore any relationship between handedness and social attitudes in a fashion similar to Niebauer et al.’s original study. The current study uses Niebauer et al.’s creationism/evolutionism scale (along with the EHI and familial sinistrality) in an attempt to replicate the original study. The creationism/evolutionism belief system well illustrates the concept of a traditional belief (creationism) being firmly adhered to in the face of what is commonly held to be ever-broadening contradictory evidence in support of evolution, the nation being split between the two belief systems, (Gallup finding 48% of Americans ascribing to the theory of creationism [Numbers, 1992, pp. ix]). In addition to the creationism/evolutionism scale, the current study also uses the Short Version of the Attitudes Toward Women Scale, the Moral Traditionalism Scale, and a modified Social Attitudes Scale. Like creationism and evolutionism, Americans (at least historically) have shown division on attitudes about gender-roles. The past 40 years have shown major shifts in Americans’ attitudes toward gender-roles and women in the workplace (Stern, Song, & O’Brien, 2004). Mason, Czajka, & Arber (1976) demonstrated a significant trend away from traditional gender attitudes during the 1960s after the implementation of the 1964 Civil Rights Act. Though the trend has shown some possible reversal or plateau in the following decade (Helmreich, Spence, & Gibson, 1982), researchers have found that the trend away from traditional gender attitudes has continued Handedness and Belief Systems 10 through the 1980s and 1990s (Mason & Lu, 1988; Twenge, 1997). While egalitarian attitudes may be a more prominent today than in the 1950s, its relevance is not lost on this study, as administrations of gender attitude measures still reveal differential effects for region and sex (McHugh & Frieze, 1997). To measure this effect, Spence, Helmreich, & Stapp’s (1973) Short Version of the Attitudes Toward Women Scale will be used. This 25-item shortened version of the 55-item Attitudes Toward Women Scale is the most widely used of gender-role attitude measures (McHugh & Frieze, 1997), and has shown its continued usefulness throughout decades of use (Loo & Thorpe, 1998). A four-point agree/disagree scale is used with each item, an example being #10: “Women should worry less about their rights and more about becoming good wives and mothers.” This scale is used to explore “attitudes about the rights and roles of women in six major areas in society: vocational, educational and intellectual roles; the freedom and independence rights of women compared to men in society; the acceptability of various dating and etiquette behaviors for men and women; the acceptability of drinking, swearing and joke-telling behaviors; the issue of premarital sex; and attitudes toward marital relationships and obligations (Loo & Thorpe, 2005, pp. 367)”. This test was administered to investigate the hypothesis that mixed-handers will exhibit more egalitarian attitudes than strong-handers. Similarly, measures of moral traditionalism since the 1940s have shown general liberalizing trends similar to those of gender-roles attitudes’ egalitarian trends, but with rise-and-fall patterns (Hastings & Hoge, 1986). The present study intends to test the “low threshold” paradigm using Conover & Feldman’s (1985) Moral Traditionalism Scale. Moral traditionalism itself generally refers to attitudes regarding family and social organization (Weisberg, 2005) and is defined by Conover & Feldman as “preference for traditional patterns of family and social organization that reflects a reverence for the past and a resistance to change (Stoker, 1987, pp. 73)”. The measure Handedness and Belief Systems 11 consists of 10 seven-point Likert scale agree/disagree items, for example: “Changes in lifestyles, such as divorce and men and women living together without being married, are signs of increasing moral decay”. My hypothesis for this scale is that mixed-handers will be more moral non-traditionalist than strong-handers. The last measure to be administered in the current study was a modified version of Grant, Ross, Button, Hannah, & Hoskins’ (2001) Social Attitudes Scale. This measure provides a bipolar liberal-conservative measure using 20 items of a highly salient nature, each item dealing with a separate social issue; for example: “Condoms should be made available to adolescents”. The items were graded on an agree/disagree seven-point Likert scale. The scale was assembled to test participants’ liberalism and conservatism in a wide age range and also participants’ estimates of other age categories’ degrees of liberalism or conservatism. Grant et al. (2001) assembled the items on the Social Attitudes Scales from other tests with which they had worked in the past, the resultant measure used in their ideology/age interaction study. The tentative prediction for this measure is that mixed-handers may display more liberal ideology than stronghanders. The attitudes being tested (attitudes toward women, moral traditionalism, and liberalism/conservatism) are complex and their development involves myriad influences and factors. Though social, cognitive, educational, and a host of other factors are involved in the creation of social attitudes, the current study intends to test the possible role of cerebral organization in creating and maintaining those beliefs. We intend to attempt to replicate Niebauer et al.’s (2004) study in which he correlated mixed-handedness with evolutionist beliefs and strong-handedness with creationist beliefs, and use the resultant theory (that mixed-handers may have lower thresholds for updating beliefs) to attempt to generalize to social attitudes. Handedness and Belief Systems 12