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Cultural and environmental influences on footedness: Cross-sectional study in urban and semi-urban Malawi
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Brain and Cognition 65 (2007) 177–183 www.elsevier.com/locate/b&c
Cultural and environmental influences on footedness: Cross-sectional study in urban and semi-urban Malawi Y.P. Zverev *, M. Mipando Physiology Department, College of Medicine, University of Malawi, P.O. Bag 360, Chichiri, Blantyre 3, Malawi Accepted 24 July 2007 Available online 10 September 2007
Abstract The present study was designed to assess cultural and environmental pressure against left-foot preference in urban and semi-urban Malawi. The findings demonstrated that, when compared to handedness, footedness appeared to be less biased behavioral laterality in culturally restrictive communities. The percentage of responders with negative views on left-foot preference was lower than that on left-hand preference (57% vs. 75%) and a smaller proportion of volunteers suggested that left-footers should be forced to change the foot (63.5% vs. 87.6%). In total, mobilizing and stabilizing tasks scored similar proportions of negative responses. Expectation of inferior performance of the left foot than the right one was the major reason for negative views on left-foot preference. Gender and driving experience had significant but weak effect on the view on left-foot preference. Most of the responders (74%) suggested that left-footers should change the foot in early family environment. Ó 2007 Elsevier Inc. All rights reserved. Keywords: Footedness; Handedness; Africa; Culture
1. Introduction Numerous studies have demonstrated that phenotypic expression of handedness experiences cultural and environmental right-sided bias but the strength of social censorship against left-handedness varies with cultural liberalism of the society (Perelle & Ehrman, 1994). In general, non-formal or permissive cultures (North America and Europe) have liberalized attitudes towards left-handedness and apply little cultural pressure to change the hand (Beuklaar & Kronenberg, 1986; Fleminger, Dalton, & Standage, 1977; Searleman & Porac, 2003), whereas formal or culturally restrictive societies have strong anti-lefthanded prejudices and practices as found in most of countries in Africa, Asia, and Latin America (Holder & Kateeba, 2004; Iwasaki, Kaiho, & Iseki, 1995; Kang & Harris, 2000; Martin & Porac, 2007; Zverev, 2004, 2006). *
Corresponding author. E-mail address: [email protected] (Y.P. Zverev).
0278-2626/$ - see front matter Ó 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.bandc.2007.07.008
According to Porac, Rees, and Buller (1990), such differences in cultural orientation to handedness might account up to 23.5% of the cross-cultural variations in handedness pattern. Unlike studies on cultural and environmental influences on hand preferences, very few publications have looked at the limits of foot use in culturally permissive and restrictive societies (Gabbard & Hart, 1995; Kang & Harris, 2000; Peters & Durding, 1979). There are some indications that footedness is a less biased behavioural laterality than handedness because the environmental and socio-cultural factors that affect hand preference are less of an influence on foot laterality (Kang & Harris, 2000; Maupas, Paysant, Datie, Martinet, & Andre, 2002; Peters, 1988, 1990; Searleman, 1980). In addition, only a few daily life feet activities are under dextral bias and changing a gear when driving might be the most important unilateral foot activity which is under environmental pressure (Gabbard & Hart, 1995; Maupas et al., 2002). However, most of published studies (Dargent-Pare, De Agostini, Mesbah, & Dellatolas, 1992;
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Gabbard & Hart, 1995; Kang & Harris, 2000; Peters & Durding, 1979) were mainly designed to assess the prevalence of footedness and its relationship with handedness rather than to investigate environmental and cultural bias directly, especially in the context of community. To the best of our knowledge, none of such studies was conducted in Africa. Numerous researchers have noted the complexity of footedness definition and evaluation (Gabbard & Hart, 1996; Sadeghi, Allard, Prince, & Labelle, 2000; Vanden-Abeele, 1980). First, motor asymmetries for foot preference and performance are weaker and less lateralized than handedness (Peters, 1990). Second, some researchers only recognized presence of foot preference in unilateral tasks (Previc, 1991) or suggested that only a few types of daily life activities of the foot are lateralized (Maupas et al., 2002). In addition, lateralized activities of the lower extremity are less complex and practiced than the use of one hand (Peters, 1990). Third, footedness might depend on behavioral contents and complexity of the motor activities because of the different roles the two feet play in execution of various posturomotor, locomotor, and operant tasks (Gabbard, 1997; Sadeghi et al., 2000). Functionally, behavioral activities of the lower extremities could be classified as mobilizing/manipulative and stabilizing and the foot which is preferred for manipulations or mobilization is commonly defined as the dominant one (Gabbard & Hart, 1996; Peters, 1988). The non-preferred (or non-dominant) foot has a secondary role in mobilizing/manipulative tasks by providing support to the actions of the dominant limb but it might play a leading role in stabilizing activities. Maupas et al. (2002) have suggested three possible aspects of footedness which reflected three types of motor activities: an effector foot, a static support foot and a dynamic support foot. Therefore, foot preference could be defined in several ways depending on the selected criteria and methodology used for assessment of functional asymmetry of the lower extremities. In the present study, footedness was defined operationally on the basis of footedness score on the Waterloo Footedness Questionnaire-Revised (WFQ-R) (Elias, Bryden, & Bulman-Fleming, 1998), which includes questions on foot preference for manipulative and stabilizing tasks. The main objective of the present survey was to assess cultural and environmental pressure against left-foot preference in urban and semi-urban Malawi and to compare it with that exerted against left-handedness. Specific objectives included assessment of the prevalence of the three categories of footedness and handedness in the study sample and relationship between these behavioral lateralities; identification of the primary agents exerting pressure against left-foot preference and timing of the foot shifting pressure; identification of the target activities against left-foot preference; and assessment of the effects of socio-demographic characteristics of the responders on acceptance of leftfootedness.
2. Materials and methods 2.1. Sample The survey was conducted in two secondary schools located in urban and semi-urban areas of Blantyre, the commercial capital of Malawi, Central Africa. Both schools belong to the Government and enroll students with different economical and social background. The permission to conduct the study was granted to the researches by educational authorities and all participants and their guardians gave the informed consent to participate in the survey. In each school one class was randomly selected in each of the four standards and all students in each selected class and their guardians (parents, elder brothers and sisters, grandparents, uncles, aunts, and other members of extended family who have responsibility for the children) as well as all school teachers were asked to participate in the survey. In total, 375 school students, 410 guardians, and 67 teachers were approached and received questionnaires in two schools. The completed questionnaires were collected in sealed boxes which were placed in the classrooms, school corridors, teachers’ offices and libraries. Some 775 questionnaires were received. The response rate among students was 90%, among teachers—94.3%, and among guardians 92%. Twenty-four questionnaires were excluded from the analysis due to missing data. In total, 751 questionnaires were analysed. Demographic characteristics of the participants are presented in Table 1.
2.2. Survey instrument The study instrument (Appendix A) consisted of questions on socio-demographic characteristics of the participants such as gender, age, tribe, occupation, marital status, religion and educational level; the Waterloo Footedness Questionnaire-Revised (WFQ-R) (Elias et al., 1998); five questions on cultural and environmental pressure against left-foot use; and 16 questions on assessment of hand preference. The subjects were also asked whether they have driving experience. The 10-item WFQ-R (Elias et al., 1998) consisted of five questions on foot preference for mobilizing and manipulative activities (such as kicking a ball, stepping on a fastmoving bug, etc.) and five questions on foot preference for stabilising activities (standing on one foot, balancing Table 1 Demographic characteristics of the study population Males
Females
Total
Age range
N
%
N
%
N
%
Pupils Teachers Guardians
161 38 194
41 9.7 49.3
164 26 168
45.8 7.3 46.9
325 64 362
43.3 8.5 48.2
14–21 24–57 29–59
Total
393
100
358
100
751
100
14–59
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on one foot, etc.). The items in the WFQ-R were vetted by the group of reviewers in order to make sure that the questions were culturally appropriate for the sample. The group consisted of the College of Medicine students and staff members and secondary school students and teachers. As a result of the revision several questions which were inquiring about foot preference for activities which are not common in Malawi were rephrased. However, rephrasing of the questions has not changed the nature of behavioural activity they were targeting. For example, we replaced a question on foot preference for balancing on a railway track with a question on foot preference for balancing while standing on a brick because some of the participants were not be able to imagine themselves performing balancing on a railway track. Foot preference for each behavioural activity was assessed on a five-point scale from minus 2 (always left) to plus 2 (always right). The scores for individual items were summed and the mean footedness score for each participant was calculated. In differentiating the three categories of footedness we utilized the modified decision rules described by Peters and Servos (1989) and Martin and Porac (2007). Participants who reported that they always or usually use the right foot for at least nine activities from the list were classified as right-footers. Conversely, those participants who always or usually preferred the left foot for at lease eight tasks from the list were classified as left-footers. The adoption of a more lax criterion for left-footedness was based on the assumption that cultural and environmental right-side bias forced some consistent left-footers to prefer the right side or to use both sides equally for at least one, usually less skilled activity (Peters & Servos, 1989). The category of mixed-footedness included wide spectrum of foot preferences ranging from ‘‘inconsistent right-footedness’’ (equal use of the both feet or preferential use of the left foot for more than one task) to ‘‘inconsistent left-footedness’’ (equal use of the both feet or preferential use of the right foot for more than two tasks). Handedness of the responders was assessed using a questionnaire which consisted of questions on hand preference for three common spontaneous unimanual activities (throwing a stone, carrying a bag, and picking up a tool from the floor), four activities influenced and marked by education and imitation (writing, drawing, holding a spoon or a knife, and giving a handshake when greeting a person), and three activities shaped by the design of certain technical equipment and tools (using a bottle opener, scissors, and opening doors and windows). Like the WFQ-R, hand preference on the handedness questionnaire was assessed on a five-point scale from minus 2 (left always) to plus 2 (right always). The criteria for handedness classification were similar to those used for classification of footedness. At the end of the questionnaires there were four additional questions on the personal experiences of the responders of any pressure to change the hand or the foot and the history of such attempts if any (Appendix A).
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The section of the instrument on socio-cultural pressure against left-footedness included a question on personal view on left-foot preference for 10 behavioural activities; a question on whether left-footers should be forced to change the foot; a question on the main reason for discouraging left-foot preference for different activities; a question on agents who normally discourage leftfoot use; and a question on the age when people should be discouraged from left-foot use (Appendix A). These questions and answer options were drafted by the authors and revised by a focus group which consisted of the College of Medicine staff and students and secondary school teachers and students. The group was asked to identify irrelevant items, to add relevant questions and answer options and to clarify confusing items. The authors then generated a new version of this section which was further reviewed by another focus group which consisted of school teachers and students and general public. After examination by this group, several items were edited. The study instrument also included an information sheet with detailed instructions on answering the questions. The information sheet stressed the fact that the questionnaire does not require any form of identification of responders such as name, initials or ID number and that the answers will be kept confidentially. The instrument and instructions were translated from English into Chichewa. The Chichewa version was checked through blind back translation. Responders had a choice to use the English or Chichewa version of the instrument. 2.3. Data analysis A standard version of SPSS 11.0.0 was used for data analysis. We used one-way v2 analysis to test whether the distribution of responses departed significantly from chance expectation of equality. v2-based Cramer’s coefficient (V) was used as a measure of effect size. 3. Results Table 2 shows the prevalence of the three categories of handedness and footedness among pupils, teachers, and guardians in the total study sample. The differences between the three social groups of volunteers in the distribution of left-, right-, and mixed-sidedness were statistically non-significant (v2 = 0.95, df = 6, p > .05 and v2 = 0.87, df = 4, p > .05 for footedness and handedness, respectively). Therefore, the there groups were combined in one group and the prevalence of the three categories of handedness and footedness was calculated for the entire sample. The mean values of footedness score for the categories of right-, left-, and mixed-footers were plus 1.87 ± 0.17, minus 1.71 ± 0.19 and plus 0.27 ± 1.04, respectively, and the mean scores for right-, left-, and mixed-handers were plus 1.89 ± 0.12, minus 1.79 ± 0.21 and plus 0.46 ± 0.91, respectively.
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Table 2 Distribution of the responders according to footedness and handedness (N of volunteers and percentage in brackets) Footedness
Handedness
LF
RF
Total
LH
RH
MH
Total
Pupils Teachers Guardians
25 (7.7) 6 (9.4) 30 (8.3)
250 (76.9) 49 (76.6) 271 (74.9)
MF 50 (15.4) 9 (14.1) 61 (16.9)
325 (100) 64 (100) 362 (100)
11 (3.4) 2 (3.1) 14 (3.9)
302 (92.9) 59 (92.2) 331 (91.4)
12 (3.7) 3 (4.7) 17 (4.7)
325 (100) 64 (100) 362 (100)
Total
61 (8.1)
570 (75.9)
120 (16.0)
751 (100)
27 (3.6)
692 (92.1)
32 (4.3)
751 (100)
LF, left-footedness; RF, right-footedness; MF, mixed-footedness; LH, left-handedness; RH, right-handedness; MH, mixed-handedness.
Volunteers were asked whether they have had personal experiences of encouragement, discouragement or special training to use a particular foot or hand for certain activities and whether they have changed foot or hand preference for one or more activities. In the total sample of 751 people, 49 responders (6.5%) noted that they had experienced pressure to change the hand and 37 of them (4.9%) had switched the hand, which indicated 75.5% success rate. In the same sample, 38 volunteers (4.9%) had experienced pressure to switch the foot and 24 responders (3.2%) had changed the side (63.1% success rate). Gender composition of the category of volunteers who reported pressure to change the hand, which was 53.1% of males and 46.9% of females was similar to that of the no pressure group (52.3% of males and 47.7% of females), whereas males were moderately overrepresented (76.3%) in the subgroup of responders who reported pressure to change the foot (v2 = 4.58, df = 1, p < .05, V = 0.273). In the side change group, most of the responders have changed the hand or foot due to various cultural and environmental reasons (81.1% and 79.2%, respectively). There was one shocking case when a responder indicated that in order to punish him for the use of the left hand for writing a parent cut of his middle finger on the left hand. The rest of the volunteers changed the side due to medical reasons such as leg or arm traumas. Our further analysis was focused on the subgroups of 30 volunteers who have changed handedness and 19 responders who have changed footedness due to various cultural reasons as it was the most prevalent form of hand and foot change reported. There were no cases of right-to-left shift in this category. Twenty-one (70%) of the 30 responders in the hand change group experienced a complete right-side shift and nine (30%) were classified as ambihanded. Nine (47.4%) of the 19 volunteers in the foot change group experienced a complete right-side shift and 10 (52.3%) responders were classified as mixed-footers. Table 3 shows congruence and incongruence between handedness and footedness of the responders. Most of right- and left-handers (80.7%) had uncrossed hand-foot preferences, 14.6% of the volunteers in these groups had inconsistent foot preferences, and 4.7%—crossed hand/ foot preferences. However, the proportion of incongruent hand and foot preferences in left-handers was higher than in right-handers (18.6% and 4.2%, respectively; v2 = 10.11, df = 1, p < .05) but the strength of this statistically
Table 3 Relationship between handedness and footedness (N of volunteers and percentage in brackets) Footedness LF
RF
MF
Total
Handedness LH 20 (74.0) RH 29 (4.2) MH 12 (37.5)
5 (18.6) 560 (80.9) 5 (15.6)
2 (7.4) 103 (14.9) 15 (46.9)
27 (100) 692 (100) 32 (100)
Total
570 (75.9)
120 (16.0)
751 (100)
61 (8.1)
LF, left-footedness; RF, right-footedness; MF, mixed-footedness; LH, left-handedness; RH, right-handedness; MH, mixed-handedness.
significant difference was weak (V = 0.130). Some 46.9% of mixed-handers were also classified as mixed-footers, 37.5%—left-footers and 15.6%—right-footers. In the most prevalent hand change category of the responders who experienced a complete left-to-right shift, 6 (28.6%) of the 21 responders were classified as left-footers, 10 responders (47.6%)—right-footers, and five responders (23.8%)—mixed-footers. Volunteers were asked about their opinion on left-foot preference for 10 activities listed in the WFQ-R. Fiftyseven point one percent of them (429 people) indicated that the left foot should not be preferred for at least one activity from the list. However, most of the responders with a negative view on left-hand preference (85.1 %) selected more than one activity. v2 analysis demonstrated that only gender and driving experience had statistically significant but weak effects on the distribution of responders with positive and negative views on left-foot preference (v2 = 47.13, df = 1, p < .001, V = 0.251 and v2 = 4.76, df = 1, p < .05, V = 0.080, respectively). In general, the proportion of responders with a negative view on left-foot preference was higher among males than females (69.0% vs. 44.1%), and non-drivers than drivers (59.2% vs. 49.7%). At the same time, deviation from chance in the distribution of volunteers with positive and negative views on left-foot preference according to age group, education, social status, religion, tribe, footedness, handedness, history of switched-hand and/or foot and pressure to switch the hand and/or foot was not statistically significant. Table 4 shows the proportions of responders with a negative attitude towards left-foot preference for various activities. Volunteers with positive views on left-footedness were
Y.P. Zverev, M. Mipando / Brain and Cognition 65 (2007) 177–183 Table 4 Number and percentage of the responders with negative view on left-foot preference for various behavioral activities
1 2 3 4 5 6 7 8 9 10
Activity
N
%
Kicking a ball to hit a target straight in front of you Picking up a little stone with toes Stepping on a fast-moving bug Standing on one foot Smoothing soil or sand Stepping up onto a chair with one foot (the foot which you place on the chair first) Balancing on one foot while standing on a brick on another foot Hopping on one foot Pushing a shovel into the ground Supporting weight during relaxed standing on both feet Average for mobilizing activities (1, 2, 3, 5, 9) Average for stabilizing activities (4, 6, 7, 8, 10)
281 254 268 245 142 263
37.4 33.8 35.7 32.6 18.9 35.0
207
27.6
207 152 248 219 234
27.6 20.2 33.0 29.2 31.2
not considered for calculation of these proportions. There was a statistically significant but moderate deviation from equal proportions in the distribution of responses (v2 = 51.14, df = 9, p < .001, V = 0.345). Three foot mobilizing tasks (kicking a ball, stepping on a fast-moving bug, and picking up a stone with toes) were the top target activities against left-foot preference whereas one foot mobilizing activity (smoothing sand) and two stabilizing tasks (balancing and pushing a shovel into the ground) were at the bottom of the list. In total, five mobilizing activities of the foot (items 1–3, 5, and 9) and five stabilizing tasks (items 4, 6–8, and 10) scored similar percentage of negative responses (29.2 % vs. 31.2 %). Volunteers with negative views on left-footedness were asked to select the major reason against left-foot preference from the list of nine answer options and an additional open ended option. The distribution of answers is shown in Table 5. The total sample demonstrated a statistically significant and very strong deviation from chance in this category (v2 = 360.18, df = 9, p < .001, V = 0.916). There was also a statistically significant moderate difference in the distribution of responses between mobilizing and stabilizing tasks (v2 = 96.99, df = 9, p < .001, V = 0.475). The assumption that the left foot is less skilled than the right
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one was the most common reason for a negative attitude toward left-foot preference for mobilizing tasks followed by the indication that the left foot is less powerful than the right one and that most people do not use the left foot for the listed activities. For stabilizing tasks, the assumption that the left foot is less powerful than the right one was the leading reason for a negative view on left-foot preference followed by the indication that the left foot is less skilled than the right one and that the left-foot use might be dangerous for a person. Responders with a negative view on left-footedness were asked whether left-footers should change the foot. Some 65.3% of them responded that left-footers should not be forced to change the foot even if they thought that it is not appropriate. Thirty-four point seven percent of the volunteers thought that it is not appropriated to prefer left-foot use and left-footers should be discouraged from left-foot preference. Responders were also asked who usually discourage left-foot preference in their communities. They were instructed to select one item from the list of seven with an additional open ended option. The frequencies in this category departed significantly and strongly from chance expectation of equality (v2 = 213.10, df = 7, p < .001, V = 0.705). Parents and close relatives (44.6%) were the primary group of people who usually discourage left-foot preference followed by church leaders (24.3%), friends (14.5%) and elders (8.6%). Participants were asked to select from the list of six options the most appropriate age when people should be discouraged from left-foot use. Most of the volunteers (77.6%) responded that people should stop preferring the left foot as soon as somebody noticed their left-footedness or at pre-school age. The distribution of answers showed a statistically significant and strong deviation from chance (v2 = 206.6, df = 5, p < .001, V = 0.694). 4. Discussion The present study was an extension of our previous survey which was focused on assessment of cultural and environmental bias toward right-handedness in urban and
Table 5 Reported main reasons for negative attitude towards left-foot (LF) preference for mobilizing and stabilizing activities
1 2 3 4 5 6 7 8 9 10
Reasons
Mobilizing activities N
%
N
%
N
%
LF is less powerful than the right one LF is less skilled than the right one Using the LF reflects bad intensions of a person Most people do not use the LF for the listed activities People do not like to see somebody using the left foot in public It is disrespectful to use the LH It is not convenient to use the LF because of the location of a device Using the LF might be dangerous for yourself Using the LF might be dangerous for people who are around you Other reasons
108 144 13 65 9 20 10 25 23 8
25.4 33.9 3.1 15.3 2.1 4.7 2.4 5.9 5.4 1.9
156 64 35 57 8 3 9 79 9 6
36.6 15.2 8.2 13.4 1.9 0.7 2.1 18.5 2.1 1.4
264 208 48 122 17 23 19 104 32 14
35.2 27.7 6.4 16.2 2.3 3.1 2.5 13.8 4.3 1.9
Figures represent numbers (N) and percentages (%) of the responders.
Stabilizing activities
Total
182
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semi-urban Malawi (Zverev, 2006). Therefore, we had a rare opportunity to compare cultural and environmental pressure against left-footedness with that exerted against left-handedness in the same community. The findings of the present study complemented our previous report (Zverev, 2006), which demonstrated that urban and semi-urban Malawian population is very restrictive for the use of the left extremities. However, when compared to handedness, footedness appeared to be a less biased behavioral laterality which is in agreement with previous studies (Gabbard & Iteya, 1996; Kang & Harris, 2000; Peters, 1988). Several findings supported our conclusion. First, the percentage of responders with a negative view on left-foot preference was 18% lower than that on left-hand preference (57% vs. 75%). In addition, 87.6% of the responders suggested that left-handers should be forced to change the side while only 63.5% of the volunteers considered similar action against left-footers. Second, the prevalence of crossed hand/foot preference in the right-shift subgroup of responders who changed the hand due to cultural and environmental reasons was considerably higher than in the overall group of righthanders (28.6% vs. 4.2%). This finding suggested that some congruent left-handers/footers have switched the hand from the left to the right side without changing foot preference. Third, Gabbard and Iteya (1996) have suggested that due to a weaker effect of environmental factors on hand laterality compare to foot preference, the probability of mixed-sidedness should be greater for the feet than for the hands. The results of the present study confirmed this suggestion as the prevalence of mixed-footedness was almost four times higher than that of mixed-handedness (16% vs. 4.3%). Fourth, in the study sample, more responders have experienced pressure to change the hand compare to the foot (6.5% vs. 4.9%) and as a result of such pressure 4.9% of the responders have changed the hand and only 2.6% have changed the foot from the left to the right side. The success rate of the attempted changes in foot preference was considerably lower than hand switching attempts (63.1% vs. 75.5%). Fifth, in samples from culturally permissive countries values for the prevalence of left-side preference for the hands and feet are compatible and vary between 6% and 8% (Gabbard & Iteya, 1996). Similar to other culturally restrictive countries, like Korea (Kang & Harris, 2000) there were about twice the number of left-footers than left-handers in our study sample. This fact also supported our suggestion that the pressures against left-foot use might be weaker than that against left-hand preference in the Malawian population. Most of the responders in the study sample demonstrated uncrossed lateral preferences between the hand and the foot and the prevalence of crossed hand/foot preferences among right- and left-handers in the present study was within the range of other populations (Dargent-Pare
et al., 1992; Elias et al., 1998; Kang & Harris, 2000; Martin & Machado, 2005). The principal topic of this paper was centered on the specific factors that influence footedness expression in the population of culturally restrictive urban and semi-urban Malawi. From this point of view, two factors might by especially important: the primary target activities and the reasons for a disapproval of the left-foot use. The results indicated that both functional types of behavioral activities (mobilizing/manipulative and stabilizing) scored similar proportions of negative responses. However, skilled unipedal actions such as kicking a ball, stepping on a fastmoving bug and picking up a stone with toes were on the top of the list of the most likely target behavior against left-foot use. The major reason for a disapproval of the left-foot use for mobilizing activities was an assumption that it is less skilled than the right one, while a suggestion that the left foot is weaker than the right foot was the major reason against left-hand use for stabilizing tasks. It is interesting that quite similar percentage of the responders in our previous survey (Zverev, 2006) noted inferior performance of the left hand as the major reason for a disapproval of its use. At the same time, a smaller proportion of the responders in the present study gave cultural reasons against left-foot use compare to the percentage of volunteers with a similar view on left-hand preference (26%– 28% and 38%, respectively). In addition, substantial proportion of the volunteers (11.3% for foot mobilizing activities and 18.1% for foot stabilizing tasks) indicated that the potential harm for a left-footer or people around him is the main reason against left-foot preference. However, as we noted early, there is an evidence of social and cultural conformity in all reasons for a disapproval of the left-side use. The present study is in agreement with our previous survey (Zverev, 2006), which indicated that the pressure against left-side use is exerted from the home rather than from school as about 74% of the responders indicated that left-footers should change the foot in early family environment (pre-school age or as soon as somebody noticed that a person prefers using the left foot). However, there were some differences between findings of the two studies in terms of the distribution of sources of pressure against left-side use. Smaller proportions of the responders indicated that parents and close relatives were the primary source of pressure against left-footedness compare to lefthandedness (44.6% vs. 63.4%) but larger percentages of the volunteers claimed that church leaders and friends are the main source of the discouragement of the left-foot use (24.3% vs. 7.6% and 14.5% vs. 8.2%). About 3% of the responders indicated the important role of driving instructors in changing the foot. The proportion of the volunteers who claimed that teachers are the primary agents of pressure against left-footedness was smaller than that for left-handedness (4.2% vs. 12%). In essence, the findings of the present study complemented our previous observation (Zverev, 2006) that negative views on left-side preference were equally shared by
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most socio-demographic groups of people, which might be attributed to the multicultural nature of the population of urban and semi-urban Malawi. Only gender and driving experience had statistically significant effects on the attitude towards left-footedness. However, low values of Cramer’s coefficient suggested that these effects were likely to be the results of relatively large sample size. The present study also demonstrated some gender differences in the pressure to change the foot but not the hand. In general, there were more males than females in the subgroup of volunteers who reported pressure to change the foot which might be explained by engagement of males in footballrelated activities (Martin & Machado, 2005). The present study was focused on assessment of cultural and environmental bias in urban and semi-urban communities. Due to economic, educational and cultural differences between rural and urban populations in Malawi our findings might have limited application to rural settings. An additional study is required to assess cultural and environmental pressure against left-sidedness in rural populations. In conclusion, the present study demonstrated presence of a strong dextral bias in the population of urban and semi-urban Malawi with foot mobilizing activities being on the top of the list of the most target behaviors. However, the strength of environmental and cultural pressure against left-footedness was weaker than that against lefthandedness. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/ j.bandc.2007.07.008. References Beuklaar, L. J., & Kronenberg, P. M. (1986). Changes over time in the relationship between hand preference and writing hand among lefthanders. Neuropsychologia, 24, 301–303. Dargent-Pare, C., De Agostini, M., Mesbah, M., & Dellatolas, G. (1992). Foot and eye preference in adults: Relationship with handedness, sex and age. Cortex, 28, 343–345. Elias, L. J., Bryden, M. P., & Bulman-Fleming, M. B. (1998). Footedness is a better predictor than handedness for emotional lateralization. Neuropsychologia, 36, 37–43. Fleminger, J. J., Dalton, R., & Standage, K. (1977). Age as a factor in the handedness of adults. Neuropsychologia, 15, 471–473. Gabbard, C. (1997). Coming to term with laterality. Journal of Psychology, 131, 561–564. Gabbard, C., & Iteya, M. (1996). Foot laterality in children, adolescents and adults. Laterality, 1, 199–205.
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Gabbard, C., & Hart, S. (1996). A question of foot dominance. Journal of General Psychology, 123, 289–296. Gabbard, C., & Hart, S. (1995). Foot performance of right- and lefthanders: A question on environmental influence. Perceptual and Motor Skills, 80, 671–674. Holder, M. K., & Kateeba, D. (2004). Hand preference survey of 5136 school children in Western Uganda. Laterality, 9, 201–207. Iwasaki, S., Kaiho, T., & Iseki, K. (1995). Handedness trends across age groups in a Japanese sample of 2316. Perceptual and Motor Skills, 80, 979–994. Kang, Y., & Harris, L. J. (2000). Handedness and footedness in Korean college students. Brain and Cognition, 43, 268–274. Martin, W. L. B., & Machado, A. H. (2005). Deriving estimates of contralateral footedness from prevalence rates in samples of Brazilian and non-Brazilian right- and left-handers. Laterality: Asymmetries of body, brain, and cognition, 10, 353–358. Martin, W. L. B., & Porac, C. (2007). Patterns of handedness and footedness in switched and non-switched Brazilian left-handers: Cultural effects on the development of lateral preferences. Developmental Neuropsychology, 31, 159–179. Maupas, E., Paysant, J., Datie, A. M., Martinet, N., & Andre, J. M. (2002). Functional asymmetries of the lower limbs. A comparison between clinical assessment of laterality, isokinetic evaluation and electrogoniometric monitoring of knees during walking. Gait and Posture, 16, 304–312. Perelle, I., & Ehrman, L. (1994). An international study of human handedness: The data. Behaviour Genetics, 24, 217–227. Peters, M. (1988). Footedness: asymmetries in foot preference and skill and neuro-psychological assessment of foot movement. Psychological Bulletin, 103, 179–192. Peters, M. (1990). Neuropsychological identification of motor problems. Can we learn something from the feet and leg that hands and arms will not tell us? Neuropsychological Review, 1, 165–183. Peters, M., & Durding, B. M. (1979). Left-handers and right-handers compared on a motor task. Journal of Motor Behavior, 11, 103–111. Peters, M., & Servos, P. (1989). Preference of subgroups of left-handers and right-handers. Canadian Journal of Psychology, 43, 341–358. Porac, C., Rees, L., & Buller, T. (1990). Switching hands: A place for left hand use in a right hand world. In S. Coren (Ed.), Left handedness: Behavioural implications and abnormalities (pp. 259–290). Amsterdam: Elsevier Science. Previc, F. H. (1991). A general theory concerning origins of cerebral lateralization in humans. Psychological Review, 98, 299–334. Sadeghi, H., Allard, P., Prince, F., & Labelle, H. (2000). Symmetry and limb dominance an able-bodied gait: A review. Gait and Posture, 12, 34–45. Searleman, A. (1980). Subject variables and cerebral organization for language. Cortex, 16, 239–254. Searleman, A., & Porac, C. (2003). Lateral preference profiles and right shift attempt histories of consistent and inconsistent left-handers. Brain and Cognition, 52, 175–180. Vanden-Abeele, J. (1980). Comments on the functional asymmetries of the lower extremities. Cortex, 16, 325–329. Zverev, Y. P. (2004). Prevalence of the three categories of handedness among Malawian school children. Collegium Antropologicum, 28, 205–208. Zverev, Y. P. (2006). Cultural and environmental pressure against lefthand preference in urban and semi-urban Malawi. Brain and Cognition, 60, 295–303.
Brain and Cognition 65 (2007) 177–183 www.elsevier.com/locate/b&c
Cultural and environmental influences on footedness: Cross-sectional study in urban and semi-urban Malawi Y.P. Zverev *, M. Mipando Physiology Department, College of Medicine, University of Malawi, P.O. Bag 360, Chichiri, Blantyre 3, Malawi Accepted 24 July 2007 Available online 10 September 2007
Abstract The present study was designed to assess cultural and environmental pressure against left-foot preference in urban and semi-urban Malawi. The findings demonstrated that, when compared to handedness, footedness appeared to be less biased behavioral laterality in culturally restrictive communities. The percentage of responders with negative views on left-foot preference was lower than that on left-hand preference (57% vs. 75%) and a smaller proportion of volunteers suggested that left-footers should be forced to change the foot (63.5% vs. 87.6%). In total, mobilizing and stabilizing tasks scored similar proportions of negative responses. Expectation of inferior performance of the left foot than the right one was the major reason for negative views on left-foot preference. Gender and driving experience had significant but weak effect on the view on left-foot preference. Most of the responders (74%) suggested that left-footers should change the foot in early family environment. Ó 2007 Elsevier Inc. All rights reserved. Keywords: Footedness; Handedness; Africa; Culture
1. Introduction Numerous studies have demonstrated that phenotypic expression of handedness experiences cultural and environmental right-sided bias but the strength of social censorship against left-handedness varies with cultural liberalism of the society (Perelle & Ehrman, 1994). In general, non-formal or permissive cultures (North America and Europe) have liberalized attitudes towards left-handedness and apply little cultural pressure to change the hand (Beuklaar & Kronenberg, 1986; Fleminger, Dalton, & Standage, 1977; Searleman & Porac, 2003), whereas formal or culturally restrictive societies have strong anti-lefthanded prejudices and practices as found in most of countries in Africa, Asia, and Latin America (Holder & Kateeba, 2004; Iwasaki, Kaiho, & Iseki, 1995; Kang & Harris, 2000; Martin & Porac, 2007; Zverev, 2004, 2006). *
Corresponding author. E-mail address: [email protected] (Y.P. Zverev).
0278-2626/$ - see front matter Ó 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.bandc.2007.07.008
According to Porac, Rees, and Buller (1990), such differences in cultural orientation to handedness might account up to 23.5% of the cross-cultural variations in handedness pattern. Unlike studies on cultural and environmental influences on hand preferences, very few publications have looked at the limits of foot use in culturally permissive and restrictive societies (Gabbard & Hart, 1995; Kang & Harris, 2000; Peters & Durding, 1979). There are some indications that footedness is a less biased behavioural laterality than handedness because the environmental and socio-cultural factors that affect hand preference are less of an influence on foot laterality (Kang & Harris, 2000; Maupas, Paysant, Datie, Martinet, & Andre, 2002; Peters, 1988, 1990; Searleman, 1980). In addition, only a few daily life feet activities are under dextral bias and changing a gear when driving might be the most important unilateral foot activity which is under environmental pressure (Gabbard & Hart, 1995; Maupas et al., 2002). However, most of published studies (Dargent-Pare, De Agostini, Mesbah, & Dellatolas, 1992;
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Gabbard & Hart, 1995; Kang & Harris, 2000; Peters & Durding, 1979) were mainly designed to assess the prevalence of footedness and its relationship with handedness rather than to investigate environmental and cultural bias directly, especially in the context of community. To the best of our knowledge, none of such studies was conducted in Africa. Numerous researchers have noted the complexity of footedness definition and evaluation (Gabbard & Hart, 1996; Sadeghi, Allard, Prince, & Labelle, 2000; Vanden-Abeele, 1980). First, motor asymmetries for foot preference and performance are weaker and less lateralized than handedness (Peters, 1990). Second, some researchers only recognized presence of foot preference in unilateral tasks (Previc, 1991) or suggested that only a few types of daily life activities of the foot are lateralized (Maupas et al., 2002). In addition, lateralized activities of the lower extremity are less complex and practiced than the use of one hand (Peters, 1990). Third, footedness might depend on behavioral contents and complexity of the motor activities because of the different roles the two feet play in execution of various posturomotor, locomotor, and operant tasks (Gabbard, 1997; Sadeghi et al., 2000). Functionally, behavioral activities of the lower extremities could be classified as mobilizing/manipulative and stabilizing and the foot which is preferred for manipulations or mobilization is commonly defined as the dominant one (Gabbard & Hart, 1996; Peters, 1988). The non-preferred (or non-dominant) foot has a secondary role in mobilizing/manipulative tasks by providing support to the actions of the dominant limb but it might play a leading role in stabilizing activities. Maupas et al. (2002) have suggested three possible aspects of footedness which reflected three types of motor activities: an effector foot, a static support foot and a dynamic support foot. Therefore, foot preference could be defined in several ways depending on the selected criteria and methodology used for assessment of functional asymmetry of the lower extremities. In the present study, footedness was defined operationally on the basis of footedness score on the Waterloo Footedness Questionnaire-Revised (WFQ-R) (Elias, Bryden, & Bulman-Fleming, 1998), which includes questions on foot preference for manipulative and stabilizing tasks. The main objective of the present survey was to assess cultural and environmental pressure against left-foot preference in urban and semi-urban Malawi and to compare it with that exerted against left-handedness. Specific objectives included assessment of the prevalence of the three categories of footedness and handedness in the study sample and relationship between these behavioral lateralities; identification of the primary agents exerting pressure against left-foot preference and timing of the foot shifting pressure; identification of the target activities against left-foot preference; and assessment of the effects of socio-demographic characteristics of the responders on acceptance of leftfootedness.
2. Materials and methods 2.1. Sample The survey was conducted in two secondary schools located in urban and semi-urban areas of Blantyre, the commercial capital of Malawi, Central Africa. Both schools belong to the Government and enroll students with different economical and social background. The permission to conduct the study was granted to the researches by educational authorities and all participants and their guardians gave the informed consent to participate in the survey. In each school one class was randomly selected in each of the four standards and all students in each selected class and their guardians (parents, elder brothers and sisters, grandparents, uncles, aunts, and other members of extended family who have responsibility for the children) as well as all school teachers were asked to participate in the survey. In total, 375 school students, 410 guardians, and 67 teachers were approached and received questionnaires in two schools. The completed questionnaires were collected in sealed boxes which were placed in the classrooms, school corridors, teachers’ offices and libraries. Some 775 questionnaires were received. The response rate among students was 90%, among teachers—94.3%, and among guardians 92%. Twenty-four questionnaires were excluded from the analysis due to missing data. In total, 751 questionnaires were analysed. Demographic characteristics of the participants are presented in Table 1.
2.2. Survey instrument The study instrument (Appendix A) consisted of questions on socio-demographic characteristics of the participants such as gender, age, tribe, occupation, marital status, religion and educational level; the Waterloo Footedness Questionnaire-Revised (WFQ-R) (Elias et al., 1998); five questions on cultural and environmental pressure against left-foot use; and 16 questions on assessment of hand preference. The subjects were also asked whether they have driving experience. The 10-item WFQ-R (Elias et al., 1998) consisted of five questions on foot preference for mobilizing and manipulative activities (such as kicking a ball, stepping on a fastmoving bug, etc.) and five questions on foot preference for stabilising activities (standing on one foot, balancing Table 1 Demographic characteristics of the study population Males
Females
Total
Age range
N
%
N
%
N
%
Pupils Teachers Guardians
161 38 194
41 9.7 49.3
164 26 168
45.8 7.3 46.9
325 64 362
43.3 8.5 48.2
14–21 24–57 29–59
Total
393
100
358
100
751
100
14–59
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on one foot, etc.). The items in the WFQ-R were vetted by the group of reviewers in order to make sure that the questions were culturally appropriate for the sample. The group consisted of the College of Medicine students and staff members and secondary school students and teachers. As a result of the revision several questions which were inquiring about foot preference for activities which are not common in Malawi were rephrased. However, rephrasing of the questions has not changed the nature of behavioural activity they were targeting. For example, we replaced a question on foot preference for balancing on a railway track with a question on foot preference for balancing while standing on a brick because some of the participants were not be able to imagine themselves performing balancing on a railway track. Foot preference for each behavioural activity was assessed on a five-point scale from minus 2 (always left) to plus 2 (always right). The scores for individual items were summed and the mean footedness score for each participant was calculated. In differentiating the three categories of footedness we utilized the modified decision rules described by Peters and Servos (1989) and Martin and Porac (2007). Participants who reported that they always or usually use the right foot for at least nine activities from the list were classified as right-footers. Conversely, those participants who always or usually preferred the left foot for at lease eight tasks from the list were classified as left-footers. The adoption of a more lax criterion for left-footedness was based on the assumption that cultural and environmental right-side bias forced some consistent left-footers to prefer the right side or to use both sides equally for at least one, usually less skilled activity (Peters & Servos, 1989). The category of mixed-footedness included wide spectrum of foot preferences ranging from ‘‘inconsistent right-footedness’’ (equal use of the both feet or preferential use of the left foot for more than one task) to ‘‘inconsistent left-footedness’’ (equal use of the both feet or preferential use of the right foot for more than two tasks). Handedness of the responders was assessed using a questionnaire which consisted of questions on hand preference for three common spontaneous unimanual activities (throwing a stone, carrying a bag, and picking up a tool from the floor), four activities influenced and marked by education and imitation (writing, drawing, holding a spoon or a knife, and giving a handshake when greeting a person), and three activities shaped by the design of certain technical equipment and tools (using a bottle opener, scissors, and opening doors and windows). Like the WFQ-R, hand preference on the handedness questionnaire was assessed on a five-point scale from minus 2 (left always) to plus 2 (right always). The criteria for handedness classification were similar to those used for classification of footedness. At the end of the questionnaires there were four additional questions on the personal experiences of the responders of any pressure to change the hand or the foot and the history of such attempts if any (Appendix A).
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The section of the instrument on socio-cultural pressure against left-footedness included a question on personal view on left-foot preference for 10 behavioural activities; a question on whether left-footers should be forced to change the foot; a question on the main reason for discouraging left-foot preference for different activities; a question on agents who normally discourage leftfoot use; and a question on the age when people should be discouraged from left-foot use (Appendix A). These questions and answer options were drafted by the authors and revised by a focus group which consisted of the College of Medicine staff and students and secondary school teachers and students. The group was asked to identify irrelevant items, to add relevant questions and answer options and to clarify confusing items. The authors then generated a new version of this section which was further reviewed by another focus group which consisted of school teachers and students and general public. After examination by this group, several items were edited. The study instrument also included an information sheet with detailed instructions on answering the questions. The information sheet stressed the fact that the questionnaire does not require any form of identification of responders such as name, initials or ID number and that the answers will be kept confidentially. The instrument and instructions were translated from English into Chichewa. The Chichewa version was checked through blind back translation. Responders had a choice to use the English or Chichewa version of the instrument. 2.3. Data analysis A standard version of SPSS 11.0.0 was used for data analysis. We used one-way v2 analysis to test whether the distribution of responses departed significantly from chance expectation of equality. v2-based Cramer’s coefficient (V) was used as a measure of effect size. 3. Results Table 2 shows the prevalence of the three categories of handedness and footedness among pupils, teachers, and guardians in the total study sample. The differences between the three social groups of volunteers in the distribution of left-, right-, and mixed-sidedness were statistically non-significant (v2 = 0.95, df = 6, p > .05 and v2 = 0.87, df = 4, p > .05 for footedness and handedness, respectively). Therefore, the there groups were combined in one group and the prevalence of the three categories of handedness and footedness was calculated for the entire sample. The mean values of footedness score for the categories of right-, left-, and mixed-footers were plus 1.87 ± 0.17, minus 1.71 ± 0.19 and plus 0.27 ± 1.04, respectively, and the mean scores for right-, left-, and mixed-handers were plus 1.89 ± 0.12, minus 1.79 ± 0.21 and plus 0.46 ± 0.91, respectively.
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Table 2 Distribution of the responders according to footedness and handedness (N of volunteers and percentage in brackets) Footedness
Handedness
LF
RF
Total
LH
RH
MH
Total
Pupils Teachers Guardians
25 (7.7) 6 (9.4) 30 (8.3)
250 (76.9) 49 (76.6) 271 (74.9)
MF 50 (15.4) 9 (14.1) 61 (16.9)
325 (100) 64 (100) 362 (100)
11 (3.4) 2 (3.1) 14 (3.9)
302 (92.9) 59 (92.2) 331 (91.4)
12 (3.7) 3 (4.7) 17 (4.7)
325 (100) 64 (100) 362 (100)
Total
61 (8.1)
570 (75.9)
120 (16.0)
751 (100)
27 (3.6)
692 (92.1)
32 (4.3)
751 (100)
LF, left-footedness; RF, right-footedness; MF, mixed-footedness; LH, left-handedness; RH, right-handedness; MH, mixed-handedness.
Volunteers were asked whether they have had personal experiences of encouragement, discouragement or special training to use a particular foot or hand for certain activities and whether they have changed foot or hand preference for one or more activities. In the total sample of 751 people, 49 responders (6.5%) noted that they had experienced pressure to change the hand and 37 of them (4.9%) had switched the hand, which indicated 75.5% success rate. In the same sample, 38 volunteers (4.9%) had experienced pressure to switch the foot and 24 responders (3.2%) had changed the side (63.1% success rate). Gender composition of the category of volunteers who reported pressure to change the hand, which was 53.1% of males and 46.9% of females was similar to that of the no pressure group (52.3% of males and 47.7% of females), whereas males were moderately overrepresented (76.3%) in the subgroup of responders who reported pressure to change the foot (v2 = 4.58, df = 1, p < .05, V = 0.273). In the side change group, most of the responders have changed the hand or foot due to various cultural and environmental reasons (81.1% and 79.2%, respectively). There was one shocking case when a responder indicated that in order to punish him for the use of the left hand for writing a parent cut of his middle finger on the left hand. The rest of the volunteers changed the side due to medical reasons such as leg or arm traumas. Our further analysis was focused on the subgroups of 30 volunteers who have changed handedness and 19 responders who have changed footedness due to various cultural reasons as it was the most prevalent form of hand and foot change reported. There were no cases of right-to-left shift in this category. Twenty-one (70%) of the 30 responders in the hand change group experienced a complete right-side shift and nine (30%) were classified as ambihanded. Nine (47.4%) of the 19 volunteers in the foot change group experienced a complete right-side shift and 10 (52.3%) responders were classified as mixed-footers. Table 3 shows congruence and incongruence between handedness and footedness of the responders. Most of right- and left-handers (80.7%) had uncrossed hand-foot preferences, 14.6% of the volunteers in these groups had inconsistent foot preferences, and 4.7%—crossed hand/ foot preferences. However, the proportion of incongruent hand and foot preferences in left-handers was higher than in right-handers (18.6% and 4.2%, respectively; v2 = 10.11, df = 1, p < .05) but the strength of this statistically
Table 3 Relationship between handedness and footedness (N of volunteers and percentage in brackets) Footedness LF
RF
MF
Total
Handedness LH 20 (74.0) RH 29 (4.2) MH 12 (37.5)
5 (18.6) 560 (80.9) 5 (15.6)
2 (7.4) 103 (14.9) 15 (46.9)
27 (100) 692 (100) 32 (100)
Total
570 (75.9)
120 (16.0)
751 (100)
61 (8.1)
LF, left-footedness; RF, right-footedness; MF, mixed-footedness; LH, left-handedness; RH, right-handedness; MH, mixed-handedness.
significant difference was weak (V = 0.130). Some 46.9% of mixed-handers were also classified as mixed-footers, 37.5%—left-footers and 15.6%—right-footers. In the most prevalent hand change category of the responders who experienced a complete left-to-right shift, 6 (28.6%) of the 21 responders were classified as left-footers, 10 responders (47.6%)—right-footers, and five responders (23.8%)—mixed-footers. Volunteers were asked about their opinion on left-foot preference for 10 activities listed in the WFQ-R. Fiftyseven point one percent of them (429 people) indicated that the left foot should not be preferred for at least one activity from the list. However, most of the responders with a negative view on left-hand preference (85.1 %) selected more than one activity. v2 analysis demonstrated that only gender and driving experience had statistically significant but weak effects on the distribution of responders with positive and negative views on left-foot preference (v2 = 47.13, df = 1, p < .001, V = 0.251 and v2 = 4.76, df = 1, p < .05, V = 0.080, respectively). In general, the proportion of responders with a negative view on left-foot preference was higher among males than females (69.0% vs. 44.1%), and non-drivers than drivers (59.2% vs. 49.7%). At the same time, deviation from chance in the distribution of volunteers with positive and negative views on left-foot preference according to age group, education, social status, religion, tribe, footedness, handedness, history of switched-hand and/or foot and pressure to switch the hand and/or foot was not statistically significant. Table 4 shows the proportions of responders with a negative attitude towards left-foot preference for various activities. Volunteers with positive views on left-footedness were
Y.P. Zverev, M. Mipando / Brain and Cognition 65 (2007) 177–183 Table 4 Number and percentage of the responders with negative view on left-foot preference for various behavioral activities
1 2 3 4 5 6 7 8 9 10
Activity
N
%
Kicking a ball to hit a target straight in front of you Picking up a little stone with toes Stepping on a fast-moving bug Standing on one foot Smoothing soil or sand Stepping up onto a chair with one foot (the foot which you place on the chair first) Balancing on one foot while standing on a brick on another foot Hopping on one foot Pushing a shovel into the ground Supporting weight during relaxed standing on both feet Average for mobilizing activities (1, 2, 3, 5, 9) Average for stabilizing activities (4, 6, 7, 8, 10)
281 254 268 245 142 263
37.4 33.8 35.7 32.6 18.9 35.0
207
27.6
207 152 248 219 234
27.6 20.2 33.0 29.2 31.2
not considered for calculation of these proportions. There was a statistically significant but moderate deviation from equal proportions in the distribution of responses (v2 = 51.14, df = 9, p < .001, V = 0.345). Three foot mobilizing tasks (kicking a ball, stepping on a fast-moving bug, and picking up a stone with toes) were the top target activities against left-foot preference whereas one foot mobilizing activity (smoothing sand) and two stabilizing tasks (balancing and pushing a shovel into the ground) were at the bottom of the list. In total, five mobilizing activities of the foot (items 1–3, 5, and 9) and five stabilizing tasks (items 4, 6–8, and 10) scored similar percentage of negative responses (29.2 % vs. 31.2 %). Volunteers with negative views on left-footedness were asked to select the major reason against left-foot preference from the list of nine answer options and an additional open ended option. The distribution of answers is shown in Table 5. The total sample demonstrated a statistically significant and very strong deviation from chance in this category (v2 = 360.18, df = 9, p < .001, V = 0.916). There was also a statistically significant moderate difference in the distribution of responses between mobilizing and stabilizing tasks (v2 = 96.99, df = 9, p < .001, V = 0.475). The assumption that the left foot is less skilled than the right
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one was the most common reason for a negative attitude toward left-foot preference for mobilizing tasks followed by the indication that the left foot is less powerful than the right one and that most people do not use the left foot for the listed activities. For stabilizing tasks, the assumption that the left foot is less powerful than the right one was the leading reason for a negative view on left-foot preference followed by the indication that the left foot is less skilled than the right one and that the left-foot use might be dangerous for a person. Responders with a negative view on left-footedness were asked whether left-footers should change the foot. Some 65.3% of them responded that left-footers should not be forced to change the foot even if they thought that it is not appropriate. Thirty-four point seven percent of the volunteers thought that it is not appropriated to prefer left-foot use and left-footers should be discouraged from left-foot preference. Responders were also asked who usually discourage left-foot preference in their communities. They were instructed to select one item from the list of seven with an additional open ended option. The frequencies in this category departed significantly and strongly from chance expectation of equality (v2 = 213.10, df = 7, p < .001, V = 0.705). Parents and close relatives (44.6%) were the primary group of people who usually discourage left-foot preference followed by church leaders (24.3%), friends (14.5%) and elders (8.6%). Participants were asked to select from the list of six options the most appropriate age when people should be discouraged from left-foot use. Most of the volunteers (77.6%) responded that people should stop preferring the left foot as soon as somebody noticed their left-footedness or at pre-school age. The distribution of answers showed a statistically significant and strong deviation from chance (v2 = 206.6, df = 5, p < .001, V = 0.694). 4. Discussion The present study was an extension of our previous survey which was focused on assessment of cultural and environmental bias toward right-handedness in urban and
Table 5 Reported main reasons for negative attitude towards left-foot (LF) preference for mobilizing and stabilizing activities
1 2 3 4 5 6 7 8 9 10
Reasons
Mobilizing activities N
%
N
%
N
%
LF is less powerful than the right one LF is less skilled than the right one Using the LF reflects bad intensions of a person Most people do not use the LF for the listed activities People do not like to see somebody using the left foot in public It is disrespectful to use the LH It is not convenient to use the LF because of the location of a device Using the LF might be dangerous for yourself Using the LF might be dangerous for people who are around you Other reasons
108 144 13 65 9 20 10 25 23 8
25.4 33.9 3.1 15.3 2.1 4.7 2.4 5.9 5.4 1.9
156 64 35 57 8 3 9 79 9 6
36.6 15.2 8.2 13.4 1.9 0.7 2.1 18.5 2.1 1.4
264 208 48 122 17 23 19 104 32 14
35.2 27.7 6.4 16.2 2.3 3.1 2.5 13.8 4.3 1.9
Figures represent numbers (N) and percentages (%) of the responders.
Stabilizing activities
Total
182
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semi-urban Malawi (Zverev, 2006). Therefore, we had a rare opportunity to compare cultural and environmental pressure against left-footedness with that exerted against left-handedness in the same community. The findings of the present study complemented our previous report (Zverev, 2006), which demonstrated that urban and semi-urban Malawian population is very restrictive for the use of the left extremities. However, when compared to handedness, footedness appeared to be a less biased behavioral laterality which is in agreement with previous studies (Gabbard & Iteya, 1996; Kang & Harris, 2000; Peters, 1988). Several findings supported our conclusion. First, the percentage of responders with a negative view on left-foot preference was 18% lower than that on left-hand preference (57% vs. 75%). In addition, 87.6% of the responders suggested that left-handers should be forced to change the side while only 63.5% of the volunteers considered similar action against left-footers. Second, the prevalence of crossed hand/foot preference in the right-shift subgroup of responders who changed the hand due to cultural and environmental reasons was considerably higher than in the overall group of righthanders (28.6% vs. 4.2%). This finding suggested that some congruent left-handers/footers have switched the hand from the left to the right side without changing foot preference. Third, Gabbard and Iteya (1996) have suggested that due to a weaker effect of environmental factors on hand laterality compare to foot preference, the probability of mixed-sidedness should be greater for the feet than for the hands. The results of the present study confirmed this suggestion as the prevalence of mixed-footedness was almost four times higher than that of mixed-handedness (16% vs. 4.3%). Fourth, in the study sample, more responders have experienced pressure to change the hand compare to the foot (6.5% vs. 4.9%) and as a result of such pressure 4.9% of the responders have changed the hand and only 2.6% have changed the foot from the left to the right side. The success rate of the attempted changes in foot preference was considerably lower than hand switching attempts (63.1% vs. 75.5%). Fifth, in samples from culturally permissive countries values for the prevalence of left-side preference for the hands and feet are compatible and vary between 6% and 8% (Gabbard & Iteya, 1996). Similar to other culturally restrictive countries, like Korea (Kang & Harris, 2000) there were about twice the number of left-footers than left-handers in our study sample. This fact also supported our suggestion that the pressures against left-foot use might be weaker than that against left-hand preference in the Malawian population. Most of the responders in the study sample demonstrated uncrossed lateral preferences between the hand and the foot and the prevalence of crossed hand/foot preferences among right- and left-handers in the present study was within the range of other populations (Dargent-Pare
et al., 1992; Elias et al., 1998; Kang & Harris, 2000; Martin & Machado, 2005). The principal topic of this paper was centered on the specific factors that influence footedness expression in the population of culturally restrictive urban and semi-urban Malawi. From this point of view, two factors might by especially important: the primary target activities and the reasons for a disapproval of the left-foot use. The results indicated that both functional types of behavioral activities (mobilizing/manipulative and stabilizing) scored similar proportions of negative responses. However, skilled unipedal actions such as kicking a ball, stepping on a fastmoving bug and picking up a stone with toes were on the top of the list of the most likely target behavior against left-foot use. The major reason for a disapproval of the left-foot use for mobilizing activities was an assumption that it is less skilled than the right one, while a suggestion that the left foot is weaker than the right foot was the major reason against left-hand use for stabilizing tasks. It is interesting that quite similar percentage of the responders in our previous survey (Zverev, 2006) noted inferior performance of the left hand as the major reason for a disapproval of its use. At the same time, a smaller proportion of the responders in the present study gave cultural reasons against left-foot use compare to the percentage of volunteers with a similar view on left-hand preference (26%– 28% and 38%, respectively). In addition, substantial proportion of the volunteers (11.3% for foot mobilizing activities and 18.1% for foot stabilizing tasks) indicated that the potential harm for a left-footer or people around him is the main reason against left-foot preference. However, as we noted early, there is an evidence of social and cultural conformity in all reasons for a disapproval of the left-side use. The present study is in agreement with our previous survey (Zverev, 2006), which indicated that the pressure against left-side use is exerted from the home rather than from school as about 74% of the responders indicated that left-footers should change the foot in early family environment (pre-school age or as soon as somebody noticed that a person prefers using the left foot). However, there were some differences between findings of the two studies in terms of the distribution of sources of pressure against left-side use. Smaller proportions of the responders indicated that parents and close relatives were the primary source of pressure against left-footedness compare to lefthandedness (44.6% vs. 63.4%) but larger percentages of the volunteers claimed that church leaders and friends are the main source of the discouragement of the left-foot use (24.3% vs. 7.6% and 14.5% vs. 8.2%). About 3% of the responders indicated the important role of driving instructors in changing the foot. The proportion of the volunteers who claimed that teachers are the primary agents of pressure against left-footedness was smaller than that for left-handedness (4.2% vs. 12%). In essence, the findings of the present study complemented our previous observation (Zverev, 2006) that negative views on left-side preference were equally shared by
Y.P. Zverev, M. Mipando / Brain and Cognition 65 (2007) 177–183
most socio-demographic groups of people, which might be attributed to the multicultural nature of the population of urban and semi-urban Malawi. Only gender and driving experience had statistically significant effects on the attitude towards left-footedness. However, low values of Cramer’s coefficient suggested that these effects were likely to be the results of relatively large sample size. The present study also demonstrated some gender differences in the pressure to change the foot but not the hand. In general, there were more males than females in the subgroup of volunteers who reported pressure to change the foot which might be explained by engagement of males in footballrelated activities (Martin & Machado, 2005). The present study was focused on assessment of cultural and environmental bias in urban and semi-urban communities. Due to economic, educational and cultural differences between rural and urban populations in Malawi our findings might have limited application to rural settings. An additional study is required to assess cultural and environmental pressure against left-sidedness in rural populations. In conclusion, the present study demonstrated presence of a strong dextral bias in the population of urban and semi-urban Malawi with foot mobilizing activities being on the top of the list of the most target behaviors. However, the strength of environmental and cultural pressure against left-footedness was weaker than that against lefthandedness. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/ j.bandc.2007.07.008. References Beuklaar, L. J., & Kronenberg, P. M. (1986). Changes over time in the relationship between hand preference and writing hand among lefthanders. Neuropsychologia, 24, 301–303. Dargent-Pare, C., De Agostini, M., Mesbah, M., & Dellatolas, G. (1992). Foot and eye preference in adults: Relationship with handedness, sex and age. Cortex, 28, 343–345. Elias, L. J., Bryden, M. P., & Bulman-Fleming, M. B. (1998). Footedness is a better predictor than handedness for emotional lateralization. Neuropsychologia, 36, 37–43. Fleminger, J. J., Dalton, R., & Standage, K. (1977). Age as a factor in the handedness of adults. Neuropsychologia, 15, 471–473. Gabbard, C. (1997). Coming to term with laterality. Journal of Psychology, 131, 561–564. Gabbard, C., & Iteya, M. (1996). Foot laterality in children, adolescents and adults. Laterality, 1, 199–205.
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