Independence of data points in the measurement of hand preferences in primates: Statistical problem or urban myth?

Hopkins, William D.

doi:10.1002/ajpa.22248

Cited by 51 publications

(65 citation statements)

References 49 publications

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“…Based on the total left-and right-hand frequencies, z-scores were used to evaluate whether the hand preferences of individual subjects deviated significantly from chance. This is the procedure most frequently used in the non-human primate literature (see [58,59]). Subjects with z-scores greater than 1.95 or less than -1.96 were classified as right-and left-handed, respectively.…”

Section: Discussionmentioning

confidence: 99%

Genetic basis in motor skill and hand preference for tool use in chimpanzees (Pan troglodytes)

et al. 2015

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Chimpanzees are well known for their tool using abilities. Numerous studies have documented variability in tool use among chimpanzees and the role that social learning and other factors play in their development. There are also findings on hand use in both captive and wild chimpanzees; however, less understood are the potential roles of genetic and non-genetic mechanisms in determining individual differences in tool use skill and laterality. Here, we examined heritability in tool use skill and handedness for a probing task in a sample of 243 captive chimpanzees. Quantitative genetic analysis, based on the extant pedigrees, showed that overall both tool use skill and handedness were significantly heritable. Significant heritability in motor skill was evident in two genetically distinct populations of apes, and between two cohorts that received different early social rearing experiences. We further found that motor skill decreased with age and that males were more commonly left-handed than females. Collectively, these data suggest that though non-genetic factors do influence tool use performance and handedness in chimpanzees, genetic factors also play a significant role, as has been reported in humans.

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Section: Discussionmentioning

confidence: 99%

Genetic basis in motor skill and hand preference for tool use in chimpanzees (Pan troglodytes)

et al. 2015

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“…Using the cutoffs suggested by Hopkins [2013b], HI scores greater than 0.20 were considered right preference, scores less than À0.20 were considered left preference, and all other HI scores were considered no preference at the individual level. These cutoffs are comparable to z-scores of AE1.96 when at least 30 responses are collected Hopkins [2013b]. To examine handedness strength, the absolute value of HI scores was computed (ABSHI); a score of 0 indicates no lateralization whereas a score of 1.00 indicates complete lateralization.…”

Section: Discussionmentioning

confidence: 99%

Precise digit use increases the expression of handedness in Colombian spider monkeys (Ateles fusciceps rufiventris)

Nelson

Boeving

2015

American J Primatol

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Decades of research on the hand use patterns of nonhuman primates can be aptly summarized by the following phrase: measurement matters. There is a general consensus that simple reaching is a poor indicator of handedness in most species, while tasks that constrain how the hands are used elicit individual, and in some cases, population-level biases. The TUBE task has become a popular measure of handedness, although there is variability in its administration across studies. The goal of this study was to investigate whether TUBE performance is affected by tube diameter, with the hypothesis that decreasing tube diameter would increase task complexity, and therefore the expression of handedness. We predicted that hand preference strength, but not direction, would be affected by tube diameter. We administered the TUBE task using a 1.3 cm tube to Colombian spider monkeys, and compared their performance to a previous study using a larger 2.5 cm diameter tube. Hand preference strength increased significantly on the smaller diameter tube. Hand preference direction was not affected. Notably, spider monkeys performed the TUBE task using a single digit, despite the longstanding view that this species has poor dexterity. We encourage investigators who use the TUBE task to carefully consider the diameter of the tube used in testing, and to report digit use consistently across studies. In addition, we recommend that researchers who cannot use the TUBE task try to incorporate the key features from this task into their own species appropriate measures: bimanual coordination and precise digit use.

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“…Combining these bouts seemed unproblematic as capuchin monkeys demonstrate consistency of hand use across different tasks [Lilak and Phillips, 2007], and more recently Hopkins [2013b] has argued in favour of characterizing hand preferences based on consistency between tasks.…”

Section: Discussionmentioning

confidence: 99%

“…a bout of seed cracking ended only when the individual obtained the food resource or moved away [Moura and Lee, 2010]. The use of bouts potentially underestimates or favours the null hypothesis (no hand preference) [Hopkins, 2013b], hence the results presented here are conservative.…”

Section: Study Groups and Subjectsmentioning

confidence: 99%

Hand Preference during Tool Use in Wild Bearded Capuchins

Andrade

2015

IJFP

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The preferential use of one limb (lateralization) has been observed in many species. This lateralization reflects functional asymmetries of the brain. Right-handedness and left-hemisphere dominance seem to be the norm in humans. However, suggestions that vertebrates, particularly non-human primates, show handedness are contentious. Tool use could be a driver of handedness. Here I investigated hand bias during tool use activities in groups of wild capuchins (Sapajus libidinosus). I observed the use of feeding tools in wild capuchin monkeys living in the dry Caatinga forests of the Serra da Capivara National Park, Piaui, Brazil. Capuchins used three major types of feeding tools: (a) tools for probing; (b) tools for pounding/cracking, and (c) digging stones to extract tubers or roots. I recorded hand use in 118 tool use bouts. These different types of tools had different motor demands; digging tools apparently favour right-hand use. The harsh Caatinga habitat poses a strong selective pressure for tool using, which might favour increased laterality and right-hand bias. However, the extent of right-handedness associated with tool use, particularly for digging, can only be fully evaluated following studies with larger sample sizes.

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Independence of data points in the measurement of hand preferences in primates: Statistical problem or urban myth?

Cited by 51 publications

References 49 publications

Genetic basis in motor skill and hand preference for tool use in chimpanzees (Pan troglodytes)

Genetic basis in motor skill and hand preference for tool use in chimpanzees (Pan troglodytes)

Precise digit use increases the expression of handedness in Colombian spider monkeys (Ateles fusciceps rufiventris)

Hand Preference during Tool Use in Wild Bearded Capuchins

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