Comparison in oral and manual FA and oral, manual and oral-manual FP
across extent of encountering packaged food under experimental
conditions were done using the test of multiple proportion. For similar
comparisons in the non-experimental scenario, we either applied
multilevel binary logistic regression or permutation test depending on
fulfillment of statistical criteria. Test of multiple proportions was
carried out in Statistics Toolkit (StatsToDo, 2020), binomial logistic
regression and permutation test were done in RStudio v.1.4.1717(RStudio Team, 2021) and effect size index (Cohen’s d ) was
computed in an online effect size calculator (Wilson, 2001) based on
Lipsey and Wilson (2000).
While analyzing data from naturalistic settings (non-experimental
condition) for FA and FP, we treated each species separately. Due to
near complete separation of hand and mouth use in FA along encounter
with packaged food and urbanization in all species except vervet monkey,
multilevel regression generated singularities and therefore, a
permutation-based chi-square test was applied with chiperm()function in the GmAMisc package (Alberti, 2021). Hypotheses
testing in vervet monkeys (1) modeled the distribution of FA as negative
binomial using glmmTMB() function in the glmmTMB package
(Brooks et al., 2017), (2) performed model diagnostics usingtestDispersion() and simulationOutput() functions in theDHARMa (Hartig, 2021) package and (3) selected optimal model
based on Burnham and Anderson (2002).