The law of brevity in macaque vocal communication is not an artifact of analyzing mean call durations

TL;DR

This study confirms that the observed pattern of shorter, more frequent macaque calls is genuine and not due to statistical artifacts, showing a fundamental principle similar to human word brevity.

Contribution

It demonstrates that the law of brevity in macaque vocalizations is not an artifact of using mean durations, supporting its validity as a natural pattern.

Findings

Negative correlation between call frequency and mean duration confirmed

Total call duration increases with call frequency

Pattern is not due to statistical artifact

Abstract

Words follow the law of brevity, i.e. more frequent words tend to be shorter. From a statistical point of view, this qualitative definition of the law states that word length and word frequency are negatively correlated. Here the recent finding of patterning consistent with the law of brevity in Formosan macaque vocal communication (Semple et al., 2010) is revisited. It is shown that the negative correlation between mean duration and frequency of use in the vocalizations of Formosan macaques is not an artifact of the use of a mean duration for each call type instead of the customary 'word' length of studies of the law in human language. The key point demonstrated is that the total duration of calls of a particular type increases with the number of calls of that type. The finding of the law of brevity in the vocalizations of these macaques therefore defies a trivial explanation.