Pick a hand, any hand: mixed-handedness and night-sky watching in a college student sample.
Broca's (1861) case-report indicating that damage to an area in the lower, left frontal lobe of the brain (Broca's Area) is associated with impaired speech production spurred scientists to further explore behaviors and mental processes associated with localized brain functioning. Continued research in this area led to findings that the cerebral cortex of the brain is split into two hemispheres, left and right (Sperry, 1968). Moreover, studies intimated that cortical functioning is generally asymmetrical; that is, one hemisphere is usually dominant in specific functions (of., Omstein, 1997).
One of the largest literatures related to hemisphericity (the lateralization of brain cortical functioning) is the research on handedness, the hand that humans prefer to use across various tasks (Annett, 1985). Handedness has been reported as an adequate indicator of hemispheric dominance (Coulson & Lovett, 2004; Knecht et al., 2000). The stronger an individual's left-hemispheric dominance, the more right-handed the individual; the more right hemisphere dominant, the more left-handed an individual.
Findings from handedness research indicated that left-handed individuals (relative to right-handed individuals) had more divergent thought processes (Coren, 1995) and were more emotionally expressive (Jackson, 2005). Hemisphere functioning has also been related to affective style. For example, left-handers have been found to be more vulnerable to experiencing negative affective reactions, such as stress. Right-handers, conversely, were more likely to experience positive affective states (Tomarken, Davidson, & Henriques, 1990; Wheeler, Davidson, & Tomarken, 1993).
Although most handedness research has investigated left versus right-handedness, some studies have found that mixed-handedness, defined as being comfortable using either the left or right hand depending upon the task, also reflects important individual differences. Mixed-handedness likely would be an indicator of mixed-hemisphericity, what Crow, Crow, Done, and Leask (1998) called the point of "hemispheric indecision." Essentially, at this point hemispheric dominance is not asymmetrical, but rather the right and left hemispheres both provide strong input into experiences and judgments. In other words, the more fantasy-prone, creative, and negative emotional right-hemisphere and the logical, linear-thinking left-hemisphere functionally "mix" together to influence the individual's experiences and thinking (Leonhard & Brugger, 1998).
The effects of this "mixed" hemisphericity can manifest in several ways. For example, studies have found that mixed-handedness was higher among individuals diagnosed with schizophrenia (Dragovic, Hammond, Badcock, & Jablensky, 2005) and with schizotypal traits, such as magical ideation (Barnett & Corballis, 2002). Perhaps related to the unconventional thinking-style involved with schizotypy, mixed-handedness has also been associated with creativity (Weinstein & Graves, 2001).
Other research has attempted to examine handedness in relation to occupations. For example, Morton (2003) surveyed university professors across 16 disciplines and found that the largest number of right-handed professors were in microbiology (86%) and biochemistry (83%). The largest number of non-right handed professors were in astronomy (71%) and architecture (67%). These findings indicate the incidence of handedness among specific disciplines. However, what about individuals who have interests in a discipline, but do not pursue it as a vocation? For example, not everyone who visits a planetarium or takes an astronomy course will become an astronomer. These individuals, nevertheless, may have unique characteristics worthy of scientific study. The purpose of this study was to examine the relationship between handedness and the leisure corollary of the astronomy profession--night-sky watching.
Empirically, there is indirect evidence that night-sky watching and mixed-handedness might be related. For instance, both night-sky watching and mixed-handedness have been correlated with magical ideation (Barnett & Corballis, 2002; Kelly & Daughtry, 2005). Both constructs have also been related to creative/artistic interests (Kelly, 2007; Weinstein & Graves, 2001). Based on these empirical links, it was predicted that night-sky watching interest would be highest among mixed-handed than left or right-handed individuals.
Participants and Procedure
After obtaining informed consent, 128 college students (93 females) were administered the self-report measures described below. The average age of the sample as 28.6 years (SD = 10.2).
Edinburgh Handedness Inventory. Handedness was measured using Oldfield's (1971) 10-item Edinburgh Handedness Inventory (EHI). The scale is designed to measure hand preference on a variety of physical activities (i.e., "write," and "throw"). In this study, participants responded using the following 5-point scale to indicate their preference for hand use for each activity: 1 = "Always Left Hand," 2 = "Usually Left Hand," 3 = "Either Left or Right Hand," 4 = "Usually Right Hand," and 5 = "Always Right Hand."
Noctcaelador Inventory. The Noctcaelador Inventory (NI; Kelly, 2004) is a 10-item self-report scale designed to measure interest in the night-sky. Participants responded to items using a 5-point Likert scale ranging from 1 = "strongly disagree" to 5 = "strongly agree." Responses were summed to produce a total score. Higher scores indicated more noctcaelador. A sample item is "I like to go outside and look at the sky at night often."
Descriptive statistics of the NI in this sample were as follows; M = 27.5, SD = 9.0, alpha =.94. Descriptive statistics of the EHI were: M = 42.3, SD = 11.4, alpha = .96. To examine handedness in relation to the N1, EHI scores were separated into three groups: left-handed (n=13), right-handed (n=102), and mixed-handed (n=13). Categorization of the three groups was determined as follows: the left-handed responses (1 = "Always Left Hand," 2 = "Usually Left Hand) were designated as left-handed. The highest possible score for left-handed participants was 20 and the lowest score possible was 10. Hence, EHI scores of 10-20 were classified as left-handed. Scores for the right-handed group (40-50) were calculated in the same manner. The remainder of participants (scores 21-39) were classified as mixed-handed.
An Analysis of Variance (ANOVA) was calculated for the three handedness groups on NI scores. The results were significant, F (2, 125) = 6.2, p < .003. Tukey's post-hoc tests revealed that the mixed-handedness group scored significantly higher on the NI (M=35.5) than either the right-handed (M=26.5) or left-handed (M= 27.1) groups. The right and left-handed group's scores were not significantly different.
The results of this study supported the hypothesis: participants classified as mixed-handed scored significantly higher on interest in night-sky watching than those considered left or right-handed. These results were consistent with previous findings linking both night-sky watching interest and mixed-handedness to schizotypy (Barnett & Corballis, 2002; Kelly & Daughtry, 2005) and creative interests (Kelly, 2007; Weinstein & Graves, 2001). Moreover, these findings were reflective of previous research that astronomers, as a group, were likely to be classified as non-right-handed (Morton, 2003).
The findings of the present study are also somewhat consistent with theoretical writings about mixed-hemisphericity and psychological functioning. Leonhard and Brugger (1998) posited that creative and schizotypal thought are related to a decrease in left-hemisphere dominance through an over-reliance on right-hemisphere processes, termed a laterality shift. This shift might be expected to manifest as an increase in creative thought, fantasy, and perhaps psychotic-like symptoms. If the individual also maintains sufficient left-hemisphere functioning near, or equal to, the right-hemisphere functioning, the individual should continue to maintain a degree of rationality and clarity of thought. In other words, it is possible that such individuals would have a combination of right and left-hemisphere activity, with neither hemisphere being dominant enough to suppress the effect of the other. This could be conceptualized as dual hemispheric functioning.
Individuals with an interest in night-sky watching have demonstrated evidence of this dual hemispheric functioning. Specifically, night-sky interest has tended to be associated with two clusters of correlates; rational and "odd." As evidence of these clusters, night-sky watchers have reported (i) rational, reflective thinking processes (Kelly, 2005) and intellectual interests (Kelly, 2007), as well as (ii) hallucinations (Kelly, 2006) and absorptive fantasy-proneness (Kelly, Daughtry, & Kelly, 2006).
Even if hemisphericity does somehow influence interest in night-sky watching, one crucial question remains: why the night-sky? If we follow the assumption that handedness is somewhat genetic and can be seen from pre-birth (i.e., Carter-Saltzman, 1980), this would indicate handedness may create a pre-disposition to enjoy the night-sky. Potentially, however, this could create an interest in any other visual stimuli such as artwork, symbols, or shapes. So, why night-sky watching? There is some evidence that night-sky watching partly acts as a coping strategy (Kelly & Daughtry, 2007). If the night-sky is soothing to some individuals, then watching it during stressful times could positively reinforce the behavior and interest. However, there is likely more to the motivation to watch the night-sky than both coping and a brain pre-disposition.
Additional research is needed to better understand what motivates individuals to enjoy night-sky watching. Also, research should examine whether or not night-sky watching may take precedence for some individuals over other leisure activities or visual stimuli. In other words, do these individuals enjoy night-sky watching only equally as well as other activities, or does it rank higher among their interests/affinities? The results of this study provide some evidence that there may be a biological basis to interest in night-sky watching. Obviously, however, more questions than answers arise from these findings.
There are several limitations that should be considered when interpreting and generalizing the results of this study. First, the sample size was relatively small and homogeneous. Second, the equal numbers of participants classified as left and mixed-handed does not coincide with previous findings (cf., Barnett & Corballis, 2002). This could indicate that the sample was not representative of the population, or perhaps a problem with the classification system used. Third, the results relied only on self-report inventories. While handedness has been found to be a good indicator of hemisphericity (Coulson & Lovett, 2004; Knecht et al., 2000), no self-report instrument can accurately demonstrate hemispheric activity. Additional research is needed to account for these limitations and explore the questions raised previously.
Address correspondence to:
Dept. of Social Sciences
Robert Morris University
6001 University Blvd.
Moon Township, PA 15108
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WILLIAM E. KELLY
Robert Morris University
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|Author:||Kelly, William E.|
|Publication:||College Student Journal|
|Date:||Mar 1, 2009|
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