Table 5. Inter-Individual Differences in Tickling Outcomes.

Results of high-calling trait	N	Author Year
↓ susceptibility to chronic variable stress	5	Wohr 2009; Mallo 2007; Mallo 2009; Raudkivi 2012; Koiv 2016
↑ 50-kHz vocalizations in open field test	1	Garcia 2015
↑ 50-kHz vocalizations during amphetamine treatment	1	Garcio 2016
↓ anxiety/fear behaviors (more crosses in central area of open field and more rearing/locomotor activity to tickling)	2	Wohr 2009; Burgdorf 2009
↑ hippocampal cell proliferation after tickling	1	Wohr 2009
↓ approach time to self-administer tickling	1	Burgdorf 2008
↑ positive cognitive bias after tickling	1	Rygula 2012

Randomly bred rats that consistently produce more 50-kHz vocalizations during tickling (high-callers) have been found to have the following results when compared to rats consistently vocalizing less during tickling (low-callers). N = number of experiments with this finding.