# Familial sinistrals avoid exact numbers.

• Published in 2013
In the collections
We report data from an internet questionnaire of sixty number trivia. Participants were asked for the number of cups in their house, the number of cities they know and 58 other quantities. We compare the answers of familial sinistrals - individuals who are left-handed themselves or have a left-handed close blood-relative - with those of pure familial dextrals - right-handed individuals who reported only having right-handed close blood-relatives. We show that familial sinistrals use rounder numbers than pure familial dextrals in the survey responses. Round numbers in the decimal system are those that are multiples of powers of 10 or of half or a quarter of a power of 10. Roundness is a gradient concept, e.g. 100 is rounder than 50 or 200. We show that very round number like 100 and 1000 are used with 25% greater likelihood by familial sinistrals than by pure familial dextrals, while pure familial dextrals are more likely to use less round numbers such as 25, 60, and 200. We then use Sigurd's (1988, Language in Society) index of the roundness of a number and report that familial sinistrals' responses are significantly rounder on average than those of pure familial dextrals. To explain the difference, we propose that the cognitive effort of using exact numbers is greater for the familial sinistral group because their language and number systems tend to be more distributed over both hemispheres of the brain. Our data support the view that exact and approximate quantities are processed by two separate cognitive systems. Specifically, our behavioral data corroborates the view that the evolutionarily older, approximate number system is present in both hemispheres of the brain, while the exact number system tends to be localized in only one hemisphere.

## Other information

editor
Stamatakis, Emmanuel Andreas
issn
1932-6203
journal
PloS one
keywords
Anthropology,Behavior,Biology,Cognition,Cognitive neurology,Cognitive neuroscience,Cognitive psychology,Human families,Linguistic anthropology,Linguistics,Mathematics,Medicine,Mental Health,Neuroethology,Neurolinguistics,Neurological Disorders,Neurology,Neuropsychology,Neuroscience,Number concepts,Number theory,Psycholinguistics,Psychology,Research Article,Social and behavioral sciences,Sociology,Verbal behavior
number
3
pages
e59103
publisher
Public Library of Science
volume
8

### BibTeX entry

@article{Sauerland2013,
abstract = {We report data from an internet questionnaire of sixty number trivia. Participants were asked for the number of cups in their house, the number of cities they know and 58 other quantities. We compare the answers of familial sinistrals - individuals who are left-handed themselves or have a left-handed close blood-relative - with those of pure familial dextrals - right-handed individuals who reported only having right-handed close blood-relatives. We show that familial sinistrals use rounder numbers than pure familial dextrals in the survey responses. Round numbers in the decimal system are those that are multiples of powers of 10 or of half or a quarter of a power of 10. Roundness is a gradient concept, e.g. 100 is rounder than 50 or 200. We show that very round number like 100 and 1000 are used with 25{\%} greater likelihood by familial sinistrals than by pure familial dextrals, while pure familial dextrals are more likely to use less round numbers such as 25, 60, and 200. We then use Sigurd's (1988, Language in Society) index of the roundness of a number and report that familial sinistrals' responses are significantly rounder on average than those of pure familial dextrals. To explain the difference, we propose that the cognitive effort of using exact numbers is greater for the familial sinistral group because their language and number systems tend to be more distributed over both hemispheres of the brain. Our data support the view that exact and approximate quantities are processed by two separate cognitive systems. Specifically, our behavioral data corroborates the view that the evolutionarily older, approximate number system is present in both hemispheres of the brain, while the exact number system tends to be localized in only one hemisphere.},
author = {Sauerland, Uli and Gotzner, Nicole},
editor = {Stamatakis, Emmanuel Andreas},
issn = {1932-6203},
journal = {PloS one},
keywords = {Anthropology,Behavior,Biology,Cognition,Cognitive neurology,Cognitive neuroscience,Cognitive psychology,Human families,Linguistic anthropology,Linguistics,Mathematics,Medicine,Mental Health,Neuroethology,Neurolinguistics,Neurological Disorders,Neurology,Neuropsychology,Neuroscience,Number concepts,Number theory,Psycholinguistics,Psychology,Research Article,Social and behavioral sciences,Sociology,Verbal behavior},
month = {jan},
number = 3,
pages = {e59103},
publisher = {Public Library of Science},
title = {Familial sinistrals avoid exact numbers.},
url = {http://dx.plos.org/10.1371/journal.pone.0059103},
volume = 8,
year = 2013,
urldate = {2013-04-15},
collections = {Easily explained,Probability and statistics}
}