Researchers call this effect "tonic immobility".
1	Researchers	researcher	NOUN	NNS	Number=Plur	2	nsubj	2:nsubj	Discourse=context-background:61->63:2|Entity=(46-person-new-cf2-1-sgl)
2	call	call	VERB	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	0	root	0:root	_
3	this	this	DET	DT	Number=Sing|PronType=Dem	4	det	4:det	Entity=(45-abstract-giv:act-cf1*-2-coref
4	effect	effect	NOUN	NN	Number=Sing	2	obj	2:obj	Entity=45)
5	"	''	PUNCT	``	_	7	punct	7:punct	SpaceAfter=No|XML=<q>
6	tonic	tonic	ADJ	JJ	Degree=Pos	7	amod	7:amod	Entity=(45-abstract-giv:act-cf1*-2-appos
7	immobility	immobility	NOUN	NN	Number=Sing	4	appos	4:appos	Entity=45)|SpaceAfter=No
8	"	''	PUNCT	''	_	7	punct	7:punct	SpaceAfter=No|XML=</q>
9	.	.	PUNCT	.	_	2	punct	2:punct	_
