Encyclopedia of Evolutionary Psychological Science

Living Edition
| Editors: Todd K. Shackelford, Viviana A. Weekes-Shackelford

Relative Brain Size, Encephalization Quotient

  • Mateo Peñaherrera AguirreEmail author
  • Michael A. Woodley of Menie
  • Heitor B F Fernandes
Living reference work entry

Later version available View entry history

DOI: https://doi.org/10.1007/978-3-319-16999-6_3098-1


The encephalization quotient is a between-species measure of relative brain size, operationalized as the ratio of actual to predicted brain mass for a given species relative to body mass. This indicator is used in comparative analyses involving different species as an index of cognitive ability.


The comparative study of the neural substrates of cognition has demonstrated to be more elusive than previously thought, with epistemological and methodological caveats that create the conditions for tireless disagreements among researchers within and between fields of study for which neuroanatomical or brain activity measures are central variables or potential correlates. This entry will deal one such neuroanatomical measure, specifically the encephalization quotient.



As neurological data that permit comparing across species or populations are difficult to collect at the physiological level (Striedter 2005), most studies use neuroanatomical measures...


Encephalization Quotient (EQ) Relative Brain Size Neuroanatomical Measures General Intelligence Factor Actual Brain Volume 
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Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  • Mateo Peñaherrera Aguirre
    • 1
    Email author
  • Michael A. Woodley of Menie
    • 2
  • Heitor B F Fernandes
    • 3
  1. 1.Department of PsychologyUniversity of New BrunswickFrederictonCanada
  2. 2.Center Leo Apostel for Interdisciplinary StudiesVrije Universiteit BrusselBrusselBelgium
  3. 3.Universidade Federal do Rio Grande do SulPorto AlegreBrazil

Section editors and affiliations

  • Catherine Salmon
    • 1
  1. 1.University of RedlandsRedlandsUSA