Table 1. Specific Methods Used for Tickling Rats.

First Author	Year	Type	Total Duration(min)	Active Tickling (min)	# of Sessions	Total time per rat (min)	Tickling Bedding
Boulay	2013	PV	?	0.5	1–6	?	Sawdust
Brudzynski	2011	P	2	1	4	8	Corn cob
Burgdorf	2001	P	0.5–2	0.15–1	2–5	8–10	None
	2005	P	2	1	4	8	Corn cob
	2008	PV	2	1	1	2	None
	2009	P	2	1	5	10	None
Cloutier	2008	PV	1	0.5	10	10	None
	2012	P	2	1	15, 17	30, 34	Wood fiber
	2013	P	2	1	21	42	Wood fiber
	2014	P	2	1	30	60	Wood fiber
	2015	P	2	1	10	20	Wood fiber
Garcia	2015	P	2	1	4	8	Wood fiber
	2016	P	2	1	4	8	Wood fiber
Hori	2009	PV	5	2	20	100	Cloth
	2013a	PV	5	2	1	5	Cloth
	2013b	PV	5	2	10	50	Cloth
	2014	PV	5	2	20	100	?
Koiv	2016	P	2	1	14	28	None
Mallo	2007	P	2	1	23, 46	46, 92	?
	2009	P	2	1	14	14	None
Natusch	2010	S	10	7	2, 5	20, 50	Aspen, None
Panksepp	2000	P	2, 5	1, 2.5	4–8	14–35	Corn cob
Paredes-Ramos	2012	PV	6	3	10	60	None
Popik	2012	PV	0.5	0.5	24	?	?
	2014	PV	?	0.5	14	?	?
Raudkivi	2012	P	2	1	14	28	None
Roccaro	2016	S	3.5	5	12	60	None
Rygula	2012	P	0.5	0.5	1	1	?
Schwarting	2007	S	10	7	3	30	Aspen
Wöhr	2009	S	10	4.5	5	50	Aspen
Yamamuro	2010	P	5	2	5	10	Cloth
	2013	P	5	2	14, 28	28, 56	Cloth

Key characteristics about the specific methods used in the 32 articles included in the analysis. Type indicated the type of tickling. (P = Panksepp, PV = Panksepp Variation, S = Schwarting), total duration of each tickling session, the time within that session that the researcher was actively tickling the rat (most sessions include rest periods during which the rat is not tickled), the total number of sessions, the total time investment per rat, and the type of ground cover/bedding. When articles had 2 experiments with different values those values are split by a comma. Articles with >2 experiments with different values have a dash indicating the range of values used.? = not reported.