Michael
J. Beran, Ph.D. 
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Beran, M. J., JohnsonPynn, J. S., & Ready, C. (2008). Quantity representation in children and rhesus monkeys: Linear versus logarithmic scales. Journal of Experimental Child Psychology, 100, 225233. The performance of 4 and 5 year old children and rhesus monkeys was compared using a computerized task for quantity assessment. Participants first learned two quantity anchor values and then responded to intermediate values by classifying them as either similar to the large anchor or the small anchor. Of primary interest was an assessment of where the point of subjective equality (PSE) occurred for each species across four different sets of anchors to determine whether the PSE occurred at the arithmetic mean or the geometric mean. Both species produced PSEs that were closer to the geometric mean for three of four anchor sets. This indicates that monkeys and children access either a logarithmic scale for quantity representation or a linear scale that is subject is scalar variability, both of which are consistent with Weber’s law and representation of quantity that takes the form of analog magnitudes. 