|
Article Excerpt
Introduction
The performances of tasks that require geographic knowledge are affected by both task demands and the cognitive resources available to the individuals doing the tasks. The spatial information required for a given task might come in verbal and/or visual--spatial forms (Bosch et al. 2001). This information may be stored in a person's memory from prior learning experiences or acquired through perceptual processes from an external source, such as a map, at the time it is needed (Sjolinder et al. 2005). (l) It is also true that some spatial tasks are relatively easy to complete, while others are relatively difficult. A task, for example, that involves searching for a map symbol with a unique characteristic should be relatively easy, while a visual search for a map symbol that shares characteristics with other map symbols should be relatively difficult (Bunch and Lloyd 2000; Lloyd 1997; Treisman and Gelade 1980).
If the research goal is to explain the variation of performance on a map-reading task, one first needs to define success and determine a specific task to be investigated. Two variables that are frequently used as measures of success in cognitive experiments are accuracy, i.e., the proportion of the decisions made that are correct, and reaction time, i.e., the elapsed time between the presentation and response to a stimulus (Prinzmetal et al. 2005). Since the person making a decision can control the processing, it is possible to trade off accuracy and reaction time (Rinkenauer et al. 2004). Together these two variables measure performance efficiency. The purpose of the current study is to consider what factors affect performance efficiency for the identification task. The experimental method selected for this study involves a simple search task using a map. Subjects were given the name of a state in the continental United States and asked to identify it on an unlabeled map as quickly and accurately as possible. Variables related to the map and to the individuals making the decisions were used to explain the efficiency of task performance.
Explaining Performance
Numerous studies have asked subjects to recall previously learned spatial information to perform a task. Some researchers have required subjects to recall novel information learned as part of the experiment while others have requested subjects to recall common knowledge learned through prior educational and life experiences (Friedman and Montello 2006; Golledge et al. 1995). Studies have tried to explain the variation of performance variables by testing for significant differences in categorical variables hypothesized to cause different levels of performance, e.g., methods of classification for choropleth maps, or by testing for significant covariations between performance variables and hypothesized continuous causal variables, e.g., study time (Brewer and Pickle 2002; Schneider and Taylor 2003). The current study follows this line of investigation by considering categorical individual differences among decision makers and the continuous differences of states. Reasonable research questions for cartographers and others interested in map-reading processes need to be considered. (1) Do evolutionary theories have any potential relevance for explaining performance on map-reading tasks? (2) What specific variables related to such theories might be used to explain map-reading performance?
Individual Differences
There are many differences among individual map readers. Below is a discussion of evolutionary theories that provide explanations for individual differences related to spatial abilities. This is followed by a discussion of the relative merits of using the biological variable sex or the social-cultural variable gender as an important measure of individual difference. The notion of brain lateralization is then discussed, along with methods that can be used to measure this individual difference and how brain lateralization interacts with spatial abilities. The final section discusses the cognitive load of mapped information and how types of memory might interact to affect performance of a map-reading task.
Evolutionary Theory
Some sex differences have been linked to environmental and social pressures that were hypothesized to result in evolutionary adaptations separating the sexes. Evidence of this hypothesized divergence is frequently reported as differences in cognitive abilities, with females having the advantage in verbal abilities and males having the advantage in spatial abilities (Weiss et al. 2003a). A male advantage has been reported for tasks involving mental rotation, geographic knowledge, map drawing and map reading (Dabbs et al. 1998; Nelson et al. 1999; Zinser et al. 2004). The Hunter-Gatherer Theory's evolutionary explanation for this advantage argues pre-agricultural males had more experiences with the geographic environment because of their greater home range (Jones et al. 2003; Ecuyer-Dab and Robert 2004a). The division of labor put males frequently in unfamiliar environments where they needed to navigate, track game, and accurately throw objects to be successful hunters (Watson and Kimura 1991; Silverman and Eals 1992; Silverman et al. 2000). The hunter hypothesis argues that the same traits that make one a good hunter also increased the likelihood the hunter would survive to pass on his genetic code, i.e., natural selection (Choi and Silverman 2003). It has also been argued these same good bunter traits make it more likely the hunter would be selected as a mate and pass on his genetic code, i.e., sexual selection (Hawkes 1991; Miller 2001; Ecuyer-Dab and Robert 2004b).
The exception to tire male advantage on spatial tasks is tire frequently reported female advantage in memory for object locations (Eals and Silverman 1994; Tottenham et al. 2003; Neave et al. 2005). This task requires subjects to recall objects learned in spatial arrays. The gatherer hypothesis argues the division of labor for pre-agricultural women made them responsible for child care and limited their spatial range (McBurney et al. 1997). Their survival required them to remember the food sources through incidental learning situations in relatively small and familiar environments (McGivern et al. 11)97, p. 1998). It is hypothesized that it is more likely the female gatherer would survive to pass on genetic code if she could accurately encode landmarks marking food locations in the local environment.
Sex vs Gender
Sex differences in cognitive abilities and strategies have been the subject of numerous studies (Adam et al. 1999; Halpern 2000; Kimura 2000; Dull and Hampson 2001; Roughgarden 2004; Gizewski et al. 2006; Rohr 2006). Most of these studies have used the obvious categories associated with sex. Because people have no problem indicating if they are female or male on a questionnaire, these traditional sex categories have been conveniently applied by geographers and others in cognition studies (Kitchin 1996; Montello et al. 1999; Rilea et al. 2004). Other researches have suggested that this traditional classification is too simplistic and that an individual's gender classification is a more meaningful concept (Popiel and De Lisi 1984; Hardwick et al. 2000; Archer and Lloyd 2002; Saucier et al. 2002; Knaak 2004). Some dictionary definitions of gender focus on the classification of nouns, pronouns, and adjectives, while others discuss sexual identity as it relates to society or culture. Being masculine or feminine is clearly more complicated than being male or female. A widely used sex-role inventory was designed to produce numerical measures of gender as continuous data on multiple scales (Bem 1974; 1975; 1977). Individuals of either sex (female or male) could have scores on the scales that indicate they only identify with the feminine or masculine category. Individuals could also have high scores on both the feminine and masculine scale or identify with both categories. These individuals are categorized as androgynous. Other individuals could have low scores on both the feminine and masculine scale or identify with neither category. These individuals are categorized as undifferentiated (Bern 1974).
There are two important reasons why gender may be a more suitable independent variable than sex in models designed to explain performance on spatial tasks. First, there is considerable evidence that spatial ability is related to sex, but not in a simple binary way. Studies that have directly considered gender as an independent variable have indicated females who scored higher on the masculinity scale also scored higher on a variety of spatial performance tasks (Signorella and Jamison 1986; Jamison and Signorella 1987). Second, experiences that provide practice in doing spatial tasks will enhance one's spatial abilities (Lloyd et al. 2002). Casey (1996) argued a female's gender identity is likely to guide interests in the activities that would provide such practice. Saucier et al. (2002) suggested that gender role socialization could mediate sex differences in spatial tasks requiring mental rotation. Our task requires both useful geographic knowledge and working memory processes to be successful. If gender role socialization encourages subjects in high feminine categories to be less interested and subjects in low feminine categories to be more interested in learning geographic knowledge, this should affect their performances on the experimental task. An interest gap might at least partially explain why Hardwick et al. (2000, p. 239) reported, "nine out of every ten finalists in the National Geography Bee are boys" or Zinser et al. (2004, p. 661) concluded, "That men displayed greater knowledge of cities and international sites suggests that they have a greater interest in geography than do women."
Lateralization and Spatial Ability
"In the human brain distinct functions tend to be localized in the left or right hemispheres, with language ability usually localized predominantly in the left and spatial recognition in the right" (Sun and Walsh 2006, p. 655). The evolution of speech in humans is also related to an asymmetry in handedness. Throughout time and for almost every cultural and ethnic group, most humans (more than 90 percent) prefer to use their right hand for most activities (Coren and Porac 1977; Corballis 2003). A recent review of brain-scanning studies related to sex differences concluded:
... it is evident that there are sex influences at all levels of the nervous system, from genetic to systems to behavioral levels. The picture of brain organization that emerges is of two complex mosaics--one male and one female--that are similar in many respects but very different in others. The way that information is processed through the two mosaics, and the behaviors that each produce, could be identical or strikingly different, depending on a host of parameters (Cahill 2006, p. 483).
Annett's Right-Shift Theory explains the genetic sex differences that are related to handedness and brain lateralization (Annett 1985; 2002). She suggested that inheritance of the right-shift gene (RS) was associated with a dominance of the left hemisphere for language and a preference for using the right hand. Inheriting the RS gene from both parents increases the probability one will be right handed and left-hemisphere dominant for language. Acquiring the RS gene from only one parent increases the probability of being right handed and left-hemisphere dominant for language, but the shift to the right is less. Not inheriting the RS gene from either parent produces no right shift and results in an equal probability of being right or left handed. Individuals who have strongly right-shifted brain structures tend to prefer encoding and processing verbal information to solve problems and complete tasks. They are also less likely to solve problems using visual processes or exhibit strong spatial abilities on standardized tests. Humans who are less right-shifted are more likely to code and process visual information to solve problems and complete tasks. They are also less likely to solve problems using verbal processes and more likely to exhibit strong spatial abilities on standardized tests. It should be noted that most people are right handed (over 90 percent) and process language (verbal information) in the left hemisphere and visual (spatial) information in the right hemisphere. Sex becomes important not because of issues related to reproduction, but because women tend to be more frequently right-shifted than men--by about 20 percent according to Annett (1999). This difference predicts women would typically have an advantage for processing verbal information and men would have advantages for processing visual information. Cognitive experiments and brain-scanning studies have supported this prediction (Gur et al. 2000; Weiss et al. 2003b).
Interaction Effects
Casey argued from Annett's Right-Shift Theory that females who are not strongly asymmetrical, i.e., not extremely right-shifted, should be genetically programmed to have better spatial abilities and more interests in spatial activities (Casey 1996; Annett 2002). Such interests in spatial activities, if pursued by individuals, should provide the practice needed to further enhance their spatial abilities. She called these females with enhanced spatial ability bent twigs. Casey's bent twig model argued that enhanced spatial abilities in females were created by the interaction of biological and environmental causes. Family handedness patterns were used to categorize individuals whose brain structure had a higher or lower probability of having enhanced spatial abilities. This was based on the postulate from Right-Shift Theory that right-handed females with immediate relatives that are also right-handed are likely to have inherited the RS gene from both parents and be extremely right-shifted. They should theoretically excel at and prefer using verbal processes to solve problems. Right-handed females with immediate family relatives that are not right-handed are more likely to have inherited the RS gene from only one parent and be less right-shifted. They also would be more likely to excel at and prefer using spatial processes to solve problems (Casey 1996). The variable Casey used to stand for environmental influences related to spatial activities was whether or not the subjects were science majors. As predicted by the bent twig model, the best performance on the rotation task was for the female subjects who had "a combination of genetic potential (assessed through familial handedness patterns) and prior experiences (assessed through choice of major and number of spatial experiences)" (Casey 1996, p. 241).
Lloyd and Bunch (2005) followed Casey's methodology and hypothesized that both male and female subjects who were right handed, had non-right-handed relatives, and had more academic geographic experiences would perform better" in a map rotation experiment. They reported a significant three-way interaction effect based on the family handedness, sex, and geographic experience of subjects. The bent-twig pattern appeared to be expressed by both female and male subjects.
Brain Asymmetry and Digital Ratio
Cognitive abilities are affected by sex hormones and can have both life-long organizational and short-term activational effects on behavior (Kimura 1989; Falter et al. 2006). Activational effects have been reported to vary over time in regular patterns that have daily, monthly, and annual cycles (Hampson 1990a, 1990b; Kimura and Hampson 1994; Ostatnikova et al. 2002). Activational hormone effects may have a negative relationship with performance for males and a positive relationship for" females (O'Connor et al. 2001; Hooven et al. 2004; Yonker et al. 2006). Bell and Saucier (2004) indicated males performing a navigation task involving pointing to target locations had much higher levels of testosterone than females. They also reported more accurate performances tot males with lower than median levels of testosterone for their group, while more accurate performances were reported for females with higher than median levels of testosterone levels for their group. This result suggests that optimal performance in general occurs with a moderate level of testosterone for the population. This moderate level is relatively low for men and relatively high for women. Gouchie and Kimura (1991) also reported a nonlinear relationship between activational testosterone levels and spatial abilities. They reported this same pattern with higher testosterone females and lower testosterone males exhibiting better spatial abilities. Falter et al. (2006) reported a similar nonlinear pattern between testosterone and targeting abilities.
There is an accumulating body of evidence that exposure to prenatal sex hormones affects asymmetries in the human body, including how the brain is structured (Manning et al....
|
